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10.1371/journal.pone.0296828

PONE-D-23-16134

Research Article

Biology and life sciences

Physiology

Physiological processes

Ingestion

Swallowing

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Pulmonology

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Otorhinolaryngology

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Nutrition

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Nutrition

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Otorhinolaryngology

Laryngology

Dysphagia

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Linguistics

Speech

Early swallowing rehabilitation and promotion of total oral intake in patients with aspiration pneumonia: A retrospective study

Relationship between early swallowing rehabilitation and promotion of total oral intake

https://orcid.org/0000-0003-1979-7083

Otaka

Yumi

Writing – original draft Writing – review & editing ¹

https://orcid.org/0000-0001-6042-7397

Harada

Yukinori

Writing – review & editing ¹ * Shiroto

Kanako

Writing – review & editing ² Morinaga

Yoshiaki

Writing – review & editing ² Shimizu

Taro

Writing – review & editing ¹

Department of Diagnostic and Generalist Medicine, Dokkyo Medical University, Mibu, Tochigi, Japan

Department of Rehabilitation, Tsugaru Hoken Medical CO-OP Kensei Hospital, Hirosaki, Aomori, Japan

Subha

Sethu Thakachy

Editor

University Putra Malaysia, MALAYSIA

The authors have declared that no competing interests exist.

* E-mail: yharada@dokkyomed.ac.jp

19 1 2024

2024

19 1

e0296828

6 6 2023 17 12 2023

2024

Otaka et al

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Objectives

To investigate the impact of early swallowing assessment and rehabilitation on the total oral intake and in-hospital mortality in patients with aspiration pneumonia.

Methods

We retrospectively analyzed the data of patients with aspiration admitted between September 1, 2015, and October 31, 2016. The inclusion criterion was total oral intake before admission. A new protocol-based intervention for appropriate early oral intake was implemented on April 1, 2016. The protocol consisted of two steps. First, a screening test was conducted on the day of admission to detect patients who were not at high risk of dysphagia. Second, patients underwent a modified water swallowing test and water swallowing test. Patients cleared by these tests immediately initiated oral intake. The primary outcome, the composite outcomes of no recovery to total oral intake at discharge, and in-hospital mortality were compared between the patients admitted pre- and post protocol intervention.

Results

A total of 188 patients were included in the analysis (pre-, 92; post-, 96). The primary outcome did not differ between the pre- and post-intervention periods (23/92 [25.0%] vs. 18/96 [18.8%], p = 0.30). After adjusting for other variables, the intervention was significantly associated with a lower risk of composite outcomes (odds ratio, 0.22, 95%CI, 0.08–0.61, p = 0.004).

Conclusion

The new protocol for early swallowing assessment, rehabilitation, and promotion of oral intake in patients admitted with aspiration pneumonia may be associated with the lower risk for the composite outcomes of in-hospital mortality and no recovery to total oral intake.

The authors received no specific funding for this work.

Data Availability

The data utilized in this study cannot be shared publicly due to its potential to reveal identifying or sensitive patient information. Nevertheless, the authors will make the data available upon receiving a reasonable request and with the approval of the ethics committee at Kensei Hospital (email: info@kensei-hp.jp).

Introduction

Aging is associated with various health problems in the world. In some countries, the rate of aging (the rate of those aged 65 or over) is exceedingly high; it was reported to be 29.8%, the highest, in Japan in 2021 [1]. Meanwhile, pneumonia and aspiration pneumonia have become more common causes of death in the aging world [2], with reports showing that 76% of deaths from aspiration pneumonia occur in people aged 75 years and over [3]. Therefore, aspiration pneumonia in older adults is a major health concern.

Older adults have several risks for aspiration pneumonia. For example, common problems in older patients, such as comorbidities [4], which can be associated with frailty [5], and delirium [6, 7], were reported as the risk factors for aspiration pneumonia in hospitalized patients [8] or nursing home residents [9]. Furthermore, neurological diseases (e.g., stroke) and neurodegenerative diseases (e.g., Parkinson’s disease), cognitive dysfunction, cancer, sarcopenia, and aging itself [10–13], which are common in the older population, can be associated with reduced swallowing function that is a key factor in the development of aspiration pneumonia [14]. Indeed, oropharyngeal dysphagia was reported to be present in approximately 90% of older patients diagnosed with pneumonia [15]. Therefore, early identification of swallowing difficulties by ongoing monitoring and regular reevaluation of swallowing function [14] and a multidisciplinary approach with registered dietitians, nutritionists, and speech therapists for tailored swallowing exercises, dietary modifications, and oral care that can mitigate the risk of dysphagia seems important for preventing aspiration pneumonia [16].

As the treatment for aspiration pneumonia in acute settings, oral care and early rehabilitation are considered as important as antimicrobial and oxygen supplementation therapies. Indeed, previous studies suggested that early swallowing assessment and rehabilitation start were associated with less deterioration in swallowing function, lower in-hospital mortality rates, and higher total oral intake rates at discharge [17–19]. However, whether implementing early swallowing assessment and rehabilitation protocol can improve these outcomes in patients hospitalized due to aspiration pneumonia remains unknown. Therefore, we conducted this study to assess the efficacy of a quality improvement action with early swallowing rehabilitation for patients with aspiration pneumonia regarding total oral intake rates at discharge and in-hospital mortality.

Methods Study design

The study was conducted at a secondary community hospital with 282 beds located in Hirosaki City, Aomori Prefecture, Japan. In September 2015, the hospital had a total of 46 doctors, 259 nurses, 34 physiotherapists, 33 occupational therapists, and 14 speech and language therapists; in April 2016, the hospital had a total of 44 doctors, 266 nurses, 34 physiotherapists, 32 occupational therapists, and 15 speech and language therapists. A multidisciplinary team that included doctors, nurses, physiotherapists, occupational therapists, speech therapists, and dental hygienists was responsible for the treatment of patients with aspiration pneumonia. This includes early swallowing rehabilitation, oral care, and patient and family education regarding feeding and swallowing. In particular, the hospital has implemented early oral interventions with speech therapists for patients hospitalized for aspiration pneumonia since 2013, including swallowing rehabilitation. Patients with aspiration pneumonia were usually admitted to the Department of General Medicine, where three doctors treated a mean of 37.4 patients with aspiration pneumonia per day from September 1, 2015, to March 31, 2016 and 49.2 patients per day in April 2016.

Intervention and participants

Before 2016, the hospital where this study was conducted had no clear criteria for early initiation of oral intake therapy in patients with aspiration pneumonia. Therefore, the decision to begin oral intake was made based on the healthcare professionals’ judgement. This may have resulted in the delayed initiation of oral intake in patients with aspiration pneumonia due to individual concerns regarding food aspiration risks. In 2016, Maeda et al. reported that food abstinence in the acute phase of aspiration pneumonia may lead to further deterioration of swallowing function and prolonged treatment duration [17]. In particular, it was reported that, for patients with aspiration pneumonia, management in hospital settings could be improved by a careful assessment of patients fit for early oral intake. Therefore, the hospital where this study was conducted initiated a project involving three doctors (two from the rehabilitation department and one from the general practice department), two nurses, and a speech and language therapist to develop a protocol for early oral intake in patients with aspiration pneumonia. The objective of this protocol was to identify patients who could safely begin oral intake.

The protocol consisted of two steps. First, patients with aspiration pneumonia were screened for a high risk of dysphagia on the day of admission using the criteria displayed in Table 1.

10.1371/journal.pone.0296828.t001

Table 1 Dysphagia screening criteria to identify high-risk patients on the day of hospital admission.

(1) Severe dysphagia prior to onset of illness (e.g., tube-fed patients).

(2) Vomiting immediately before admission, or contraindications to feeding (e.g., ileus, bleeding ulcers)

(3) Requiring oxygen administration of 3 L/min or more to achieve SpO₂ of 90% (excluding patients who have previously received home oxygen therapy of 3 L/min or more)

(4) Decreased consciousness (Japan Coma Scale II-10 or higher).

(5) Tracheostomy or tracheal cannula

(6) Admission to intensive care unit

Patients who met at least one of the criteria were judged to be at a high risk for dysphagia screening on the day of admission.

Second, patients who did not meet any of the aforementioned criteria were screened for dysphagia. This screening test used a modified water swallowing test and water swallowing test, and the appearance of either swooning, hoarseness or respiratory changes was considered abnormal. Upon screening approval, patients were considered fit to start oral intake immediately.

The objectives and details of the new protocol were provided to the responsible healthcare professionals through staff meetings. The new protocol was implemented on April 1, 2016, and a speech and language therapist was assigned to the ward not only on weekdays but also on weekends and public holidays. Patients admitted to the hospital with aspiration pneumonia between September 1, 2015, and October 31, 2016, who were apt for oral intake upon admission, were included in the analysis.

Data collection

Date extraction were performed between 1 July to 31 August 2019. The following data were retrospectively extracted from the medical records: age, sex, Charlson comorbidity index (CCI), whether the patient was at home before hospitalization, eating independence before admission (independent, partially, or fully assisted), Food Intake Level Scale (FILS) before admission and at discharge, pneumonia severity (A-DROP scores), serum albumin level on admission and at discharge (g/dL), body mass index (BMI) on admission (kg/m²), time between admission and swallowing training initiation, time from admission to oral intake initiation, and in-hospital death.

CCI is the Comorbidity Index comprising 19 items corresponding to different medical comorbid conditions. The total score of the CCI consists of a simple sum of the weights, with higher scores indicating a greater mortality risk and more severe comorbid conditions [20]. FILS is an ordinal scale to assess eating status, range 1 to 10: Level 1–3, no oral intake; level 4–6, oral intake and alternative feeding; level 7–9, oral intake only; and level 10, normal [21]. A-DROP is a scoring system that expresses the severity of pneumonia, which includes Age (≥70 years in males and ≥ 75 years in females), Dehydration (BUN ≥ 7.5 mmol/l), Respiratory failure (SaO₂ ≤ 90% or PaO₂ ≤ 60 mmHg), Orientation disturbance (confusion) and low blood Pressure (systolic blood pressure ≤ 90 mmHg) [22]. Patients were diagnosed with aspiration pneumonia when the following three criteria were fulfilled: (1) new gravity-dependent infiltration on chest X-ray or chest computed tomography; (2) the presence of at least two of the following: leukocytosis, fever, purulent sputum or elevated C-reactive protein (CRP); and (3) positive for dysphagia screening [23, 24].

The primary outcomes of the study were total oral intake at discharge and in-hospital mortality. We hypothesized that the implementation of the new protocol would increase the rate of the total oral intake at discharge and reduce the incidence of in-hospital death. Total oral intake at discharge was defined as FILS 7 or above.

Continuous variables are described as mean± standard deviation or median (1^st quartile, 3^rd quartile) and compared using the t-test or Mann–Whitney U test. Ordinal variables are described as medians (1^st quartile, 3^rd quartile), and compared using the Mann–Whitney U test. Categorical variables are described as percentages (%) and compared using the chi-square test or Fisher’s exact test. We also conducted a multivariable logistic regression analysis to evaluate the effect of the protocol intervention on the composite outcome of in-hospital mortality, or no recovery to total oral intake at discharge. Age, sex, BMI, CCI, FILS before admission, residential background, whether food intake was independent or assisted by other serum albumin levels at admission, and A-DROP at admission were included in the multivariate logistic regression model as variables other than the protocol intervention. We used the multiple imputation by chained equations method to impute the missing values (used "mice" package in R). P values less than 0.05 were considered significant. All statistical analyses were conducted using R 4.1.0 (R Foundation for Statistical Computing, Vienna, Austria) between 1 June to 30 September 2021. This study was conducted in accordance with the Ethical Guidelines for Clinical Research (Ministry of Health, Labor, and Welfare) and was approved by the ethics committee of Kensei Hospital. We did not obtain written informed consent from participants because the ethics committee waived written informed consent on the condition that we used an opt-out method to inform the study of the eligible participants. We disclosed the information about the study on the hospital’s website.

Results Baseline characteristics

A total of 322 patients with total oral intake were admitted to the hospital with a diagnosis of aspiration pneumonia between September 1, 2015, and October 31, 2016. After excluding 134 patients who met the high-risk criteria (88 before and 46 after the protocol intervention), 188 patients were included in the analyses. Among these patients, 92 and 96 were admitted before and after the intervention, respectively.

Table 2 presents the background data at the time of admission. There were no significant differences in age, sex, being at their residence time prior to admission, BMI, CCI, serum albumin level, or A-DROP score between the two groups. Regarding feeding status and swallowing function, the FILS and independent feeding before admission were statistically significantly higher in the group that did not receive the intervention protocol than in the group received the intervention protocol.

10.1371/journal.pone.0296828.t002

Table 2 Baseline patient characteristics.

	Before the protocol intervention (92 patients)	After the protocol intervention (96 patients)	P values
Age(Mean± SD)	82.0±9.3	81.3±13.1	0.68
Sex(female/total)(%)	37/92 (40.2%)	43/96 (44.8%)	0.53
FILS before admission(Median [1^st quartile, 3^rd quartile])	8.5 [8, 10]	8 [8, 10]	0.002
Self-supporting food intake before admission(%)	75/92 (81.5%)	64/96 (66.7%)	0.02
Serum albumin level on admission(Mean± SD)	3.0±0.6	3.0±0.5	0.97
BMI on admission(Mean± SD)	20.3±3.4(7 patients excluded)	19.4±3.8(12 patients excluded)	0.10
CCI(Median [1^st quartile, 3^rd quartile])	2 [1, 3]	2 [1, 3]	0.82
A-DROP on admission(Median [1^st quartile, 3^rd quartile])	2 [1, 2]	2 [1, 2](2 patients excluded)	0.80
Resides outside home before admission(%)	48/92(52.2%)	41/96(42.7%)	0.19

FILS, Food Intake Level Scale; BMI, body mass index; CCI, Charlson Comorbidity Index

Swallowing assessment and oral intake

The proportion of patients who started oral intake or underwent swallowing assessment within 2 days was not significantly different before and after the protocol intervention (90.2% and 96.8%, p = 0.06). The mean and median days from admission to swallowing assessment were 1.2 ± 1.5, 1 (0, 1) before the intervention, and 1.0 ± 1.1 and 1 (0, 1) after the intervention. The mean and median days from admission to the initiation of oral intake were 2.9 ± 7.8, 1 (1, 3) before the intervention, and 1.5 ± 1.6, and 1 (1, 2) after the intervention (p = 0.21). There were no significant differences in the number of days from admission to swallowing assessment (p = 0.48) or the initiation of oral intake (p = 0.21) before and after the intervention.

Clinical outcomes

The composite outcomes of in-hospital mortality and nonoral feeding at discharge did not differ between the pre- and post-intervention groups (23/92 [25.0%] vs. 18/96 [18.8%], p = 0.30) (Table 3). After adjusting for the other variables, the protocol intervention was significantly associated with a lower risk of composite outcomes (odds ratio, 0.22, 95%CI, 0.08–0.61, p = 0.004) (Table 4).

10.1371/journal.pone.0296828.t003

Table 3 Composite outcomes of in-hospital mortality and non-oral feeding at discharge in the pre- and post-intervention groups.

	Before the protocol intervention (92 patients)	After the protocol intervention (96 patients)	P values
The mean and median days from admission to swallowing assessment(Median [1^st quartile, 3^rd quartile])	1.21 [0, 1]	1.01 [0, 1]	0.48
The mean and median days from admission to the initiation of oral intake(non-oral feeding excluded)(Median [1^st quartile, 3^rd quartile])	1 [1, 3](6 patients excluded)	1[1, 2](4 patients excluded)	0.21
The length of hospital stays(Median [1^st quartile, 3^rd quartile])	19 [13, 40.5]	18.5 [12, 33.5]	0.41
In-hospital mortality(%)	8/92(8.7%)	7/96(7.3%)	0.72
Non-oral intake at discharge(%)	15/84(17.9%)	11/89(12.4%)	0.31
In-hospital mortality or non-oral intake at discharge(%)	23/92(25.0%)	18/96(18.8%)	0.30
FILS at survival discharge(Median [1^st quartile, 3^rd quartile])	8 [7, 10]	8[7, 8]	0.57
Self-supporting food intake at discharge(%)	58/84 (69.0%)	60/89 (67.4%)	0.82
Serum albumin level at discharge(Mean± SD)	2.8±0.4(17 patients excluded)	2.9±0.4(17 patients excluded)	0.12

FILS, Food Intake Level Scale

10.1371/journal.pone.0296828.t004

Table 4 Logistic regression analyses for in-hospital mortality or no recovery to total oral intake.

	Univariable (MICE) Odds ratio (95%CI)	P values	Multivariable (MICE) Odds ratio (95%CI)	P values
Intervention	0.69 (0.34–1.40)	0.30	0.22 (0.08–0.61)	0.004
Age	1.03 (0.99–1.07)	0.10	1.04 (0.98–1.09)	0.19
Sex(male)	0.93 (0.46–1.88)	0.84	1.00 (0.38–2.63)	>0.99
BMI	0.82 (0.72–0.93)	0.003	0.79 (0.66–0.94)	0.009
CCI	1.20 (0.96–1.52)	0.12	0.92 (0.64–1.33)	0.66
FILS before admission	0.32 (0.20–0.50)	<0.001	0.35 (0.19–0.65)	<0.001
At home before admission	0.21 (0.10–0.46)	<0.001	0.72 (0.25–2.08)	0.54
Self-supporting food intake before admission	0.17 (0.08–0.36)	<0.001	0.37 (0.13–1.06)	0.07
Serum albumin level on admission	0.25 (0.12–0.52)	<0.001	0.41 (0.16–1.07)	0.07
A-DROP	1.47 (1.02–2.12)	0.04	1.50 (0.87–2.60)	0.15

BMI, body mass index; CCI, Charlson Comorbidity Index; CI, confidence interval; FILS, Food Intake Level Scale

Among other outcomes, in-hospital mortality (8/92, 8.7% vs. 7/96, 7.3%; p = 0.72) and non-oral intake at discharge (15/84, 17.9% vs. 11/89, 12.4%; p = 0.31) did not differ between the pre- and post-intervention. There was no difference in the length of hospital stay (median, 19 and 18.5 days in the pre- and post-intervention groups; p = 0.41). The FILS at discharge and independence in feeding did not differ between the two groups.

Discussion

In this study, implementing a new protocol that aimed to facilitate early swallowing assessment and oral intake of patients admitted with aspiration pneumonia was significantly associated with a lower odds ratio for in-hospital mortality and no recovery to total oral intake than before the implementation. In detail, the logistic regression analyses showed that the protocol intervention was significantly associated with a lower risk of composite outcomes (odds ratio, 0.22, 95%CI, 0.08–0.61, p = 0.004).

Previous studies have assessed the effect of early swallowing assessment and initiation of oral intake on clinical outcomes, such as mortality and oral intake autonomy at discharge, in patients admitted with aspiration pneumonia. For example, Maeda et al. reported less deterioration in swallowing function and reduced mortality in patients who started oral intake or underwent swallowing assessment within 48 hours after admission [17]. In another study, Nakamura et al. reported that swallowing rehabilitation within 2 days of admission was significantly associated with a higher likelihood of total oral intake at discharge [19]. Recently, Katayama et al. found that there was no association between the timing of oral intake from time of admission and oral intake at discharge [25]. Nevertheless, they reported that their study could be underpowered for the positive association between oral intake initiation at admission and oral intake at discharge. Therefore, the early initiation of oral intake based on swallowing assessments may improve the outcomes of oral intake and mortality in patients with aspiration pneumonia.

There are two major possible explanations why the crude incidence of the primary outcome did not differ before and after the new intervention protocol in this study. First, the baseline levels of swallowing and eating were lower in the post-protocol implementation group than those in the pre-protocol implementation group. Since lower FILS before admission was associated with lower total oral intake at discharge and in-hospital death, the significantly lower FILS in the post-implementation group in this study may have masked the effects of protocol implementation. The significantly lower odds ratio of the implementation protocol for the primary outcome in the multivariable logistic regression analysis, when adjusted for several factors related to the outcome, including FILS and eating independence, supported this explanation. Second, the period from admission to swallowing assessment and oral intake did not change before and after the protocol implementation.

Maeda et al. reported less deterioration in swallowing function and reduced mortality in patients who started oral intake or underwent swallowing assessment within 48 hours after admission. In their study, 64.7% of patients started oral intake or underwent swallowing assessment within 48 hours after admission, with a mean period from admission to oral intake of 0.5 days. In our study, the proportion of patients who started oral intake or underwent a swallowing assessment within 2 days was already high before the implementation of the protocol (90.2%). Therefore, although the protocol implementation increased from this rate to approximately 7%, the difference was not statistically significant. Furthermore, the reduction in mean time from admission to oral intake initiation that decreased from 2.9 to 1.5 days promoted by the implementation of the protocol was also not statistically significant. In addition, even after the intervention, the mean duration from admission to oral intake was 1 day longer than that reported by Maeda et al. These results may suggest that not the rate of patients starting oral intake or undergoing swallowing assessment within 48 hours after admission but the duration from admission to oral intake is the key target for intervention to reduce in-hospital mortality and promote total oral intake at discharge.

This study had several limitations. First, this was a single-center study which may have limited the generalizability of the results. In particular, it was important that this study was conducted in a situation where a multidisciplinary team had already worked to initiate early rehabilitation for patients with aspiration pneumonia prior to the introduction of the protocol. Second, this study excluded patients who were not on a total oral intake prior to admission or patients who met the criteria for a high-risk profile to initiate oral intake; therefore, the effect of protocol implementation on such populations remains unknown. Third, because this was a retrospective design, some variables were missed. We used the multiple imputations by chained equations method to impute the missing values for the logistic regression models to reduce the effects of missing variables; however, these variables could still bias the study results. Fourth, the number of included patients was reduced due that strict criteria for exclusion and retrospective fashion of the study; therefore, some statistical analyses were underpowered. Future research are warranted to assess whether an early swallowing rehabilitation intervention with a similar protocol can increase the rate of total oral intake at discharge and reduce the rate of in-hospital mortality in other institutions, as well as whether this approach can be associated with better these outcomes even when including patients with higher-risk for dysphagia and its complications.

Conclusion

In conclusion, the implementation of a new protocol aimed at facilitating early swallowing assessment and promoting total oral intake in patients admitted with aspiration pneumonia may be associated with a lower risk of in-hospital mortality or no recovery of the total oral intake at discharge. However, to reduce the actual incidence of in-hospital mortality or no recovery of total oral intake at discharge, a more effective protocol that can shorten the time from admission to swallowing assessment and oral intake in admitted patients with aspiration pneumonia is needed.

References 1

World Social Report 2023: Leaving no one behind in an ageing world. https://www.un.org/development/desa/pd/sites/www.un.org.development.desa.pd/files/undesa_pd_2023_wsr-fullreport.pdf. Accessed April 3, 2023.

The top 10 causes of death [World Health Organization website]. https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death. Accessed April 3, 2023.

Gupte

, Knack

, Cramer

. Mortality from Aspiration Pneumonia: Incidence, Trends, and Risk Factors. Dysphagia. 2022 Dec;37(6):1493–1500. doi: 10.1007/s00455-022-10412-w

35099619

Marengoni

, Angleman

, Melis

, Mangialasche

, Karp

, Garmen

, et al. Aging with multimorbidity: a systematic review of the literature. Ageing Res Rev. 2011 Sep;10(4):430–9. doi: 10.1016/j.arr.2011.03.003

21402176

Vetrano

, Palmer

, Marengoni

, Marzetti

, Lattanzio

, Roller-Wirnsberger

, et al. Joint Action ADVANTAGE WP4 Group. Frailty and Multimorbidity: A Systematic Review and Meta-analysis. J Gerontol A Biol Sci Med Sci. 2019 Apr 23;74(5):659–666.

Inouye

, Westendorp

, Saczynski

. Delirium in elderly people. Lancet. 2014 Mar 8;383(9920):911–22. Epub 2013 Aug 28. doi: 10.1016/S0140-6736(13)60688-1

23992774

Marcantonio

. Delirium in Hospitalized Older Adults. N Engl J Med. 2017 Oct 12;377(15):1456–1466. doi: 10.1056/NEJMcp1605501

29020579

Ahn

, Chang

, Kim

. Postoperative Pneumonia and Aspiration Pneumonia Following Elderly Hip Fractures. J Nutr Health Aging. 2022;26(7):732–738. doi: 10.1007/s12603-022-1821-9

35842764

Langmore

, Skarupski

, Park

, Fries

. Predictors of aspiration pneumonia in nursing home residents. Dysphagia. 2002 Fall;17(4):298–307. doi: 10.1007/s00455-002-0072-5

12355145

Hannawi

, Hannawi

, Rao

, Suarez

, Bershad

. Stroke-associated pneumonia: major advances and obstacles. Cerebrovasc Dis. 2013;35(5):430–43. doi: 10.1159/000350199

23735757

Mandell

, Niederman

. Aspiration Pneumonia. N Engl J Med. 2019 Feb 14;380(7):651–663. doi: 10.1056/NEJMra1714562

30763196

Maniaci

, Lechien

, La Mantia

, Iannella

, Ferlito

, Albanese

, et al. Cognitive Impairment and Mild to Moderate Dysphagia in Elderly Patients: A Retrospective Controlled Study. Ear Nose Throat J. 2022 Mar 7:1455613211054631. doi: 10.1177/01455613211054631

35255725

Ueshima

, Shimizu

, Maeda

, Uno

, Shirai

, Sonoi

, et al. Nutritional Management in Adult Patients With Dysphagia: Position Paper From Japanese Working Group on Integrated Nutrition for Dysphagic People. J Am Med Dir Assoc. 2022 Oct;23(10):1676–1682. doi: 10.1016/j.jamda.2022.07.009

35985419

Okuni

, Ebihara

. Are Oropharyngeal Dysphagia Screening Tests Effective in Preventing Pneumonia? J Clin Med. 2022 Jan 13;11(2):370. doi: 10.3390/jcm11020370

35054063

Almirall

, Rofes

, Serra-Prat

, Icart

, Palomera

, Arreola

, et al. Oropharyngeal dysphagia is a risk factor for community-acquired pneumonia in the elderly. Eur Respir J. 2013 Apr;41(4):923–8. doi: 10.1183/09031936.00019012

22835620

Jukic Peladic

, Orlandoni

, Di Rosa

, Giulioni

, Bartoloni

, Venturini

. Multidisciplinary Assessment and Individualized Nutritional Management of Dysphagia in Older Outpatients. Nutrients. 2023 Feb 22;15(5):1103 doi: 10.3390/nu15051103

36904102

Maeda

, Koga

, Akagi

. Tentative nil per os leads to poor outcomes in older adults with aspiration pneumonia. Clin Nutr. 2016 Oct;35(5):1147–52. doi: 10.1016/j.clnu.2015.09.011

26481947

Momosaki

, Yasunaga

, Matsui

, Horiguchi

, Fushimi

, Abo

. Effect of dysphagia rehabilitation on oral intake in elderly patients with aspiration pneumonia. Geriatr Gerontol Int. 2015 Jun;15(6):694–9. doi: 10.1111/ggi.12333

25109319

Nakamura

, Kurosaki

. Effects of Early Dysphagia Rehabilitation by Speech-language-hearing Therapists on Patients with Severe Aspiration Pneumonia. Prog Rehabil Med. 2020 Sep 8;5:20200020. doi: 10.2490/prm.20200020

32908953

Charlson

, Pompei

, Ales

, MacKenzie

. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40(5):373–83. doi: 10.1016/0021-9681(87)90171-8

3558716

Kunieda

, Ohno

, Fujishima

, Hojo

, Morita

. Reliability and validity of a tool to measure the severity of dysphagia: the Food Intake LEVEL Scale. J Pain Symptom Manage. 2013 Aug;46(2):201–6. doi: 10.1016/j.jpainsymman.2012.07.020

23159683

Szabó

, Kardos

, Oláh

, Tamáska

, Hodosi

, Csánky

, et al. Severity and prognostic factors of SARS-CoV-2-induced pneumonia: The value of clinical and laboratory biomarkers and the A-DROP score. Front Med (Lausanne). 2022 Jul 22;9:920016. doi: 10.3389/fmed.2022.920016

35935801

Kohno

, Imamura

, Shindo

, Seki

, Ishida

, Teramoto

, et al. Clinical practice guidelines for nursing- and healthcare-associated pneumonia (NHCAP) [complete translation]. Respir Investig. 2013 Jun;51(2):103–26. doi: 10.1016/j.resinv.2012.11.001

23790739

Komiya

, Ishii

, Umeki

, Kawamura

, Okada

, Okabe

, et al. Computed tomography findings of aspiration pneumonia in 53 patients. Geriatr Gerontol Int. 2013 Jul;13(3):580–5. doi: 10.1111/j.1447-0594.2012.00940.x

22994842

Katayama

, Kurita

, Takada

, Miyashita

, Azuma

, Fukuhara

, et al. Door-to-oral time and in-hospital outcomes in older adults with aspiration pneumonia undergoing dysphagia rehabilitation. Clin Nutr. 2022 Oct;41(10):2219–2225. doi: 10.1016/j.clnu.2022.07.037

36081296

10.1371/journal.pone.0296828.r001

Decision Letter 0

Maniaci

Antonino

Academic Editor

2024

Antonino Maniaci

Submission Version

22 Jun 2023

PONE-D-23-16134Early swallowing rehabilitation and promotion of total oral intake in patients with aspiration pneumonia: a retrospective studyPLOS ONE

Dear Dr. Otaka,

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Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #2: Yes

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Reviewer #1: Thank you for the opportunity to review the manuscript by Otaka et al. on early swallowing rehabilitation and promotion of total oral intake in patients with aspiration pneumonia. The article is sound and well written. However, I have some issues to be addressed.

- When referring to neurodegenerative diseases and stroke as risk factor for aspiration pneumonia, the authors should also mention the impact of delirium in old hospitalized patients that may contribute to the risk to develop aspiration pneumonia (doi: 10.1007/s00134-021-06503-1 - doi: 10.3390/jcm12020435) as well as comorbidities (cardiovascular more frequently) that may lead to the fraility of old patients (doi: 10.1161/CIRCRESAHA.111.246876 - doi: 10.1111/echo.15462 - doi: 10.1038/s41569-018-0064-2). Please discuss and add these 5 references.

- Did authors asked for a waiver by the local ethical committee to perform this study? Please specify.

- Please add the reduced number of included patients and the retrospective design as limitations of the study.

- Table 3 is hard to read. Please use square brackets for interquartile range and replace “exclusion 6” with “6 patients excluded”

Reviewer #2: Introduction

Aging is associated with various health problems worldwide. By 2050, the rate of those aged 65 or over is expected to increase significantly, with pneumonia and aspiration pneumonia presenting as major health concerns. Reduced swallowing function is a key factor in the development of aspiration pneumonia, often caused by neurological and neurodegenerative diseases. Early initiation of swallowing rehabilitation and appropriate oral care can minimize the risk of recurrent aspiration pneumonia and improve the quality of life for older adults.

- Preventing dysphagia in individuals with cognitive deterioration involves early identification of swallowing difficulties and a multidisciplinary approach to management. Interventions such as tailored swallowing exercises, dietary modifications, and proper oral care can mitigate the risk of dysphagia. Ongoing monitoring and regular reevaluation of swallowing function are crucial to ensure timely adjustments to the care plan and maintain the patient's quality of life., please discuss and cite doi:10.1177/01455613211054631.

The introduction is quite lengthy and could be shortened to improve readability and retain the reader's attention.

- To prevent dysphagia in cases of gastritis and malnutrition, it is essential to adopt a well-balanced diet tailored to the individual's specific needs and tolerances. Working with a registered dietitian can help create a customized nutrition plan that addresses gastritis symptoms and supports optimal nutrient intake. Additionally, incorporating swallowing therapy and exercises can further reduce the risk of dysphagia and promote safe and efficient eating habits., please discuss and cite doi:10.1002/lary.29890

Some statistical information (e.g., percentages) might be better presented as visual aids like tables or graphs for easier comprehension.

Summarize the introduction by focusing on the main points and removing redundant information.

Include visual aids, such as tables or graphs, to present statistical data more effectively.

Methods

The study aimed to assess the efficacy of a quality improvement action in a secondary community hospital in Japan. A multidisciplinary team developed and implemented a protocol for early oral intake in patients with aspiration pneumonia. Patients admitted to the hospital with aspiration pneumonia between September 1, 2015, and October 31, 2016, were included in the analysis. Data were extracted retrospectively from the medical records, and the primary outcomes were total oral intake at discharge and in-hospital mortality.

The methods section is somewhat dense and may be difficult for readers to follow.

Some terminology and abbreviations are used without prior explanation (e.g., FILS, A-DROP scores), which could confuse readers.

Divide the methods section into subsections such as "Study Design," "Participants," "Intervention," and "Data Collection" for improved readability.

Define and explain any terminology or abbreviations before using them in the text.

Organize the content using subheadings: Divide the results into subsections with appropriate subheadings such as "Baseline Characteristics," "Swallowing Assessment and Oral Intake," and "Clinical Outcomes." This will make it easier for readers to follow the results and find the information they are interested in.

Visual aids: Include tables or graphs to present the numerical data more effectively. Visual aids can help readers grasp the information quickly and enhance their understanding of the study's findings.

Clarify abbreviations and terminology: If not previously explained in the methods section, provide definitions for abbreviations and terms used in the results section (e.g., FILS, A-DROP scores). This will ensure that readers have a clear understanding of the concepts discussed.

Emphasize significant findings: Highlight significant findings and differences between groups to help readers quickly identify the study's main outcomes. This can be done by using bold or italic formatting, or by summarizing significant results in a separate paragraph.

Discuss limitations and future research: In the discussion section, address the limitations of the study and provide suggestions for future research. This helps to put the results into context and gives readers a better understanding of the study's implications.

**********

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Reviewer #1: No

Reviewer #2: No

**********

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10.1371/journal.pone.0296828.r002

Author response to Decision Letter 0

Submission Version

15 Nov 2023

Response to Reviewer: 1

Comment 1: When referring to neurodegenerative diseases and stroke as risk factor for aspiration pneumonia, the authors should also mention the impact of delirium in old hospitalized patients that may contribute to the risk to develop aspiration pneumonia (doi: 10.1007/s00134-021-06503-1 - doi: 10.3390/jcm12020435) as well as comorbidities (cardiovascular more frequently) that may lead to the fraility of old patients (doi: 10.1161/CIRCRESAHA.111.246876 - doi: 10.1111/echo.15462 - doi: 10.1038/s41569-018-0064-2). Please discuss and add these 5 references.

Response 1: Thank you for reviewing our manuscript and giving us useful comment. We agree with the reviewer 1 that we should mention delirium and comorbidities; therefore, we revised the introduction as follows:

Page 3, lines 42-45

Comment 2: Did authors asked for a waiver by the local ethical committee to perform this study? Please specify.

Response 2: We added sentences related to the waiver of written informed consent as follows:

Page 9, lines 160-163

The ethics committee approved a waiver for written informed consent from each participant on the condition that we used an opt-out method to inform the study of the eligible participants. We disclosed the information about the study on the hospital’s website.

Comment 3: Please add the reduced number of included patients and the retrospective design as limitations of the study.

Response 3: We added some sentences related to the reduced number of included patients and the retrospective design in the limitation section as follows:

Page 17, lines 269-274

Third, because this was a retrospective design, some variables were missed. We used the multiple imputations by chained equations method to impute the missing values for the logistic regression models to reduce the effects of missing variables; however, these variables could still bias the study results. Fourth, the number of included patients was reduced due that strict criteria for exclusion and retrospective fashion of the study; therefore, some statistical analyses were underpowered.

Comment 4: Table 3 is hard to read. Please use square brackets for interquartile range and replace “exclusion 6” with “6 patients excluded”

Response 4: We revised Table 3 according to the comment of the reviewer 1 (Page 13-14).

Response to Reviewer: 2

Comment 1: Introduction. Preventing dysphagia in individuals with cognitive deterioration involves early identification of swallowing difficulties and a multidisciplinary approach to management. Interventions such as tailored swallowing exercises, dietary modifications, and proper oral care can mitigate the risk of dysphagia. Ongoing monitoring and regular reevaluation of swallowing function are crucial to ensure timely adjustments to the care plan and maintain the patient's quality of life., please discuss and cite doi:10.1177/01455613211054631.

Response 1: Thank you for reviewing our manuscript and giving us useful comments. We agree with the reviewer that we should discuss prevention for dysphagia and its complications. We added the discussion with the reference that the reviewer recommended.

Page 3-4, lines 51-55

Therefore, early identification of swallowing difficulties by ongoing monitoring and regular reevaluation of swallowing function [14] and multidisciplinary approach with registered dietitians, nutritionists, and speech therapists for tailored swallowing exercises, dietary modifications, and oral care that can mitigate the risk of dysphagia seem important for preventing aspiration pneumonia [16].

Comment 2: The introduction is quite lengthy and could be shortened to improve readability and retain the reader's attention.

Response 2: According to the reviewer’s advice, we revised the introduction.

Page 3-4, lines 35-65

Older adults have several risks for aspiration pneumonia. For example, common problems in older patients such as comorbidities [4], which can be associated with frailty [5], and delirium [6,7] were reported as the risk factors for aspiration pneumonia in hospitalized patients [8] or nursing home residents [9]. Furthermore, neurological diseases (e.g., stroke) and neurodegenerative diseases (e.g., Parkinson’s disease), cognitive dysfunction, cancer, sarcopenia, and aging itself [10,11,12,13], which are common in older population, can be associated with reduced swallowing function that is a key factor in the development of aspiration pneumonia [14]. Indeed, oropharyngeal dysphagia was reported to be present in approximately 90% of older patients diagnosed with pneumonia [15]. Therefore, early identification of swallowing difficulties by ongoing monitoring and regular reevaluation of swallowing function [14] and multidisciplinary approach with registered dietitians, nutritionists, and speech therapists for tailored swallowing exercises, dietary modifications, and oral care that can mitigate the risk of dysphagia seem important for preventing aspiration pneumonia [16].

As the treatment for aspiration pneumonia in acute settings, oral care and early rehabilitation are considered as important as antimicrobial and oxygen supplementation therapies. Indeed, previous studies suggested that early swallowing assessment and rehabilitation start was associated with less deterioration in swallowing function, lower in-hospital mortality rates, and higher total oral intake rates at discharge [17,18,19]. However, whether implementation of early swallowing assessment and rehabilitation can improve these outcomes in patients hospitalized due to aspiration pneumonia. Therefore, we conducted this study to assess the efficacy of a quality improvement action with early swallowing rehabilitation for patients with aspiration pneumonia in terms of total oral intake rates at discharge and in-hospital mortality.

Comment 3: To prevent dysphagia in cases of gastritis and malnutrition, it is essential to adopt a well-balanced diet tailored to the individual's specific needs and tolerances. Working with a registered dietitian can help create a customized nutrition plan that addresses gastritis symptoms and supports optimal nutrient intake. Additionally, incorporating swallowing therapy and exercises can further reduce the risk of dysphagia and promote safe and efficient eating habits., please discuss and cite doi:10.1002/lary.29890

Response 3: We agree with the reviewer that multidisciplinary approach for reducing the risk of dysphagia. We addressed the issue in the introduction with adding a new reference.

Page 3-4, lines 51-55

Comment 4: Some statistical information (e.g., percentages) might be better presented as visual aids like tables or graphs for easier comprehension. Summarize the introduction by focusing on the main points and removing redundant information. Include visual aids, such as tables or graphs, to present statistical data more effectively.

Response 4: According to the reviewer’s advice, we provided the tables 2-4 for presenting statistical information. We also summarized the introduction by focusing on the main points and removing redundant information.

Page 3-4, lines 35-65

As the treatment for aspiration pneumonia in acute settings, oral care and early rehabilitation are considered as important as antimicrobial and oxygen supplementation therapies. Indeed, previous studies suggested that early swallowing assessment and rehabilitation start was associated with less deterioration in swallowing function, lower in-hospital mortality rates, and higher total oral intake rates at discharge [17,18,19]. However, whether implementation of early swallowing assessment and rehabilitation can improve these outcomes in patients hospitalized due to aspiration pneumonia. Therefore, we conducted this study to assess the efficacy of a quality improvement action with early swallowing rehabilitation for patients with aspiration pneumonia in terms of total oral intake rates at discharge and in-hospital mortality.

Comment 5: Methods. The methods section is somewhat dense and may be difficult for readers to follow. Some terminology and abbreviations are used without prior explanation (e.g., FILS, A-DROP scores), which could confuse readers.

Response 5: We added explanations for special terminologies as follows:

Page 7-8, lines 126-135

CCI is the Comorbidity Index that consists of 19 items corresponding to different medical comorbid conditions. The total score of the CCI consists in a simple sum of the weights, with higher scores indicating not only a greater mortality risk but also more severe comorbid conditions [20]. FILS is an ordinal scale to assess eating status, ranged 1 to 10: level 1-3, no oral intake; level 4-6, oral intake and alternative feeding; level 7-9 oral intake only; and level 10, normal [21]. A-DROP is a scoring system that expresses the severity of pneumonia, which includes Age (≥70 years in males and ≥ 75 years in females), Dehydration (BUN ≥ 7.5 mmol/l), Respiratory failure (SaO2 ≤ 90% or PaO2 ≤ 60 mmHg), Orientation disturbance (confusion) and low blood Pressure (systolic blood Pressure ≤ 90 mmHg) [22].

Comment 6: Divide the methods section into subsections such as "Study Design," "Participants," "Intervention," and "Data Collection" for improved readability.

Response 6: According to the reviewer’s advice, we divided the methods section into “Study Design”, “Intervention and Participants” and “Data Collection”.

Comment 7: Define and explain any terminology or abbreviations before using them in the text.

Response 7: We spelled out all of the terminologies and abbreviations before using them and provided explanations for some terminologies.

Page 7-8, lines 119-135

Charlson comorbidity index (CCI), whether the patient was at home before hospitalization, eating independence before admission (independent, partially, or fully assisted), Food Intake LEVEL Scale (FILS) before admission and at discharge, pneumonia severity (A-DROP scores), serum albumin level on admission and at discharge (g/dL), body mass index (BMI) on admission (kg/m2), time between admission and swallowing training initiation, time from admission to oral intake initiation, and in-hospital death.

Comment 8: Organize the content using subheadings: Divide the results into subsections with appropriate subheadings such as "Baseline Characteristics," "Swallowing Assessment and Oral Intake," and "Clinical Outcomes." This will make it easier for readers to follow the results and find the information they are interested in.

Response 8: According to the reviewer’s advice, we divided results into some subsections such as “Baseline Characteristics”, “Swallowing Assessment and Oral Intake” and “Clinical Ourcomes”.

Comment 9: Visual aids: Include tables or graphs to present the numerical data more effectively. Visual aids can help readers grasp the information quickly and enhance their understanding of the study's findings.

Response 9: According to the reviewer’s advice, we provided tables to present the numerical data (Table 2-4).

Comment 10: Clarify abbreviations and terminology: If not previously explained in the methods section, provide definitions for abbreviations and terms used in the results section (e.g., FILS, A-DROP scores). This will ensure that readers have a clear understanding of the concepts discussed.

Response 10: According to the previous suggestion by the reviewer, we provided explanations for all abbreviations and terms in the Methods section.

Comment 11: Emphasize significant findings: Highlight significant findings and differences between groups to help readers quickly identify the study's main outcomes. This can be done by using bold or italic formatting, or by summarizing significant results in a separate paragraph.

Response 11: We apologize if we are out of line for saying this, but the guidelines of PlosOne seems not allowing the use of bold or italic for emphasizing the results. Therefore, though in all fairness, we summarized significant results in the first paragraph of the discussion section as follows:　

Page 14-15, lines 213-218

In this study, the implementation of a new protocol that aimed to facilitate early swallowing assessment and oral intake of patients admitted with aspiration pneumonia was significantly associated with a lower odds ratio for in-hospital mortality and no recovery to total oral intake than that before the implementation. In detail, the logistic regression analyses showed that the protocol intervention was significantly associated with a lower risk of composite outcomes (odds ratio, 0.22, 95%CI, 0.08-0.61, p=0.004).

Comment 12: Discuss limitations and future research: In the discussion section, address the limitations of the study and provide suggestions for future research. This helps to put the results into context and gives readers a better understanding of the study's implications.

Response 12: According to the reviewer’s advice, we added some limitations and future perspectives as follows:

Page 17, lines 262-279

This study had several limitations. First, this was a single-center study which may have limited the generalizability of the results. In particular, it was important that this study was conducted in a situation where a multidisciplinary team had already worked to initiate early rehabilitation for patients with aspiration pneumonia prior to the introduction of the protocol. Second, this study excluded patients who were not on a total oral intake prior to admission or patients who met the criteria for a high-risk profile to initiate oral intake; therefore, the effect of protocol implementation on such populations remains unknown. Third, because this was a retrospective design, some variables were missed. We used the multiple imputations by chained equations method to impute the missing values for the logistic regression models to reduce the effects of missing variables; however, these variables could still bias the study results. Fourth, the number of included patients was reduced due that strict criteria for exclusion and retrospective fashion of the study; therefore, some statistical analyses were underpowered. Future researches are warranted to assess whether an early swallowing rehabilitation intervention with the similar protocol can increase the rate of total oral intake at discharge and reduce the rate of in-hospital morality in other institutions, as well as whether this approach can be associated with the better these outcomes even when including patients with more higher-risk for dysphagia and its complications.

Attachment

Submitted filename: Response to Reviewers.docx

10.1371/journal.pone.0296828.r003

Decision Letter 1

Subha

Sethu Thakachy

Academic Editor

2024

Sethu Thakachy Subha

Submission Version

20 Dec 2023

Early swallowing rehabilitation and promotion of total oral intake in patients with aspiration pneumonia: a retrospective study

PONE-D-23-16134R1

Dear Dr. Harada,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Sethu Thakachy Subha, M.S

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #2: Yes

**********

6. Review Comments to the Author

Reviewer #2: all the revisions were addressed, the paper is improved in both structure than discussion and quality of writing. Now can be accepted. Bests

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

**********

10.1371/journal.pone.0296828.r004

Acceptance letter

Subha

Sethu Thakachy

Academic Editor

2024

Sethu Thakachy Subha

9 Jan 2024

PONE-D-23-16134R1

PLOS ONE

Dear Dr. Harada,

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on behalf of

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Academic Editor

PLOS ONE