Abstract
Objective
To evaluate the factors that influence walking ability in patients hospitalized due to aspiration pneumonia.
Methods
This retrospective observational study evaluated patients hospitalized with aspiration pneumonia. The primary endpoint was preservation of walking ability. Univariate and multivariate logistic regression analyses were performed with the preservation of walking ability as the dependent variable.
Results
A total of 143 patients were enrolled in this study. The patients were divided into two groups: those whose walking ability decreased after hospitalization (n = 61) and those whose walking ability was maintained after hospitalization (n = 82). Multivariate logistic regression analyses showed that A-DROP (odds ratio [OR] 3.006; 95% confidence interval [CI] 1.452, 6.541; P < 0.01), the Geriatric Nutritional Risk Index (OR 0.919; 95% CI 0.875, 0.960; P < 0.001) and days to initial mobilization (OR 1.221; 95% CI 1.036, 1.531; P < 0.05) were the independent early predictors for preservation of walking ability.
Conclusion
Nutritional status and early mobilization were important risk factors affecting the maintenance of walking ability in patients hospitalized due to aspiration pneumonia. Thus, a combination of nutrition and early rehabilitation is needed for these patients.
Registry of Research Studies involving Human Subjects
This study was registered with the University Hospital Medical Information Network Clinical Trial Registry (UMIN 000046923).
Keywords
Introduction
Aspiration pneumonia is defined as the misdirection of oropharyngeal or gastric contents into the larynx and lower respiratory tract. Aspiration pneumonia is a common problem among older people and its prevalence is increasing. Further, aspiration pneumonia is associated with high mortality.1,2 A 90-day mortality rate of 16.3% in patients with aspiration pneumonia has been previously reported. 3 In addition, a previous systematic review showed that in-hospital and 30-day mortality rates were higher for aspiration pneumonia than those for non-aspiration pneumonia. 4 Even if death is avoided, elderly patients are more likely to remain in the hospital longer and have lower activities of daily living (ADL) capabilities due to coexisting diseases and lower basic physical strength. 5
The cause of decreased walking ability is believed to be a complex combination of various factors, including disuse syndrome, disease, low nutrition and medication, and is also referred to as hospitalization-related functional impairment. 5 Approximately 35% of hospitalized patients have decreased ADL abilities. 6 Recent evidence indicates that early mobilization improves various factors such as functional prognosis, ADL ability and quality of life in intensive care patients. 7 Early mobilization is also associated with shorter hospital stays and lower mortality among patients with pneumonia.8,9 The increasing ageing population worldwide underlines the need to clarify the risk factors for decreased walking ability among patients with aspiration pneumonia to improve its clinical management. However, the factors influencing the decline in walking ability in patients with aspiration pneumonia have not been clarified. Thus, the present study aimed to examine the factors influencing walking ability among patients hospitalized due to aspiration pneumonia.
Patients and methods
Study design and participants
This retrospective observational study enrolled consecutive patients that were hospitalized at Seirei Mikatahara General Hospital, Hamamatsu, Japan with a diagnosis of aspiration pneumonia (International Statistical Classification of Diseases, 10th Revision, code J69) between 1 April 2015 and 31 March 2016. The diagnosis of aspiration pneumonia was established in cases of dysphagia and aspiration according to the Japanese guidelines by three or more physicians at a conference. 10 Dysphagia and aspiration were evaluated using the modified water swallow test or videoendoscopic examination of swallowing. The exclusion criteria were as follows: (i) disagreed with the use of their medical records for other purposes; (ii) incomplete analysis data; (iii) wheelchair-dependent or bedridden before admission. Participants were divided into two groups: those whose walking ability decreased after hospitalization and those whose walking ability did not decrease after hospitalization.
This study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Ethics Committee of the Seirei Mikatahara General Hospital (Approval Number: 17–50) and was registered with the University Hospital Medical Information Network Clinical Trial Registry (UMIN 000046923). The use of their medical records for other purposes was explained to all participants at the first visit using oral and written information. All participants provided written informed consent for the use of their medical records for other purposes. All patient details were de-identified. The reporting of this study conforms to STROBE guidelines. 11
Survey and measurement items
The following 28 data items were extracted from the medical records: age, height, body mass index (BMI), geriatric nutritional risk index (GNRI) score, sex, length of hospital stay, hospitalization method, medical examination subject, aspiration episode, life style before hospitalization, walking ability before hospitalization, performance status, dementia, A-DROP score, hemiplegia, hospitalization within 1 year, availability of oxygen therapy, blood urea nitrogen (BUN), total protein, serum albumin, C-reactive protein (CRP), white blood cell (WBC), availability of physical therapy, days to initial mobilization, first-time antibiotic, food intake LEVEL scale (FILS) at discharge, outcome and walking ability at discharge.
The GNRI is a simple score that can be calculated with only the serum albumin level, current weight and ideal weight. GNRI was first described in 2005 to predict malnutrition-related complications (bedsores and infections) and mortality among hospitalized elderly patients. 12 Further, it is significantly correlated with biochemical and anthropometric markers of nutritional status.13–15
For walking ability, freestanding gait was defined as the ability to walk both indoors and outdoors and assistance gait was defined as the ability to walk with the use of an assistive device. Wheelchair use was defined as the ability to stand and ride in a wheelchair. Bedridden was defined as the inability to sit in a wheelchair daily. The performance status was rated from 0 to 4 following the Eastern Cooperative Oncology Group Performance Status Scale. 16 The Nishimura Geriatric Rating Scale for Mental Status (NM scale), which is a 12-item rating scale used to observe daily behaviour from multiple perspectives, was used to classify dementia. 17 It does not require communication and can be used to assess the severity of the disease at five levels.
The A-DROP score was used to classify the severity of pneumonia. The A-DROP score, consisting of age ≥70 years in men or ≥75 years in women, BUN ≥ 21 mg/dl or dehydration, oxyhaemoglobin saturation measured by pulse oximetry ≤90% or partial oxygen pressure in the arterial blood ≤60 mmHg, confusion and systolic blood pressure ≤90 mmHg, is a modified version of the CURB-65 score proposed by the Japanese Respiratory Society in 2006. 18 Its predictive power is similar to that of the CURB-65 and Pneumonia Severity Index.19,20
The FILS is practical tool for assessing the severity of dysphagia using a 10-point observer-rating scale. 21 There are three further categories depending on the level of oral intake.
Statistical analyses
All statistical analyses were performed using IBM SPSS Statistics for Windows, Version 24.0 (IBM Corp., Armonk, NY, USA). Continuous data are presented as mean ± SD and categorical data are presented as n of patients (%). For between-group comparisons, differences in continuous variables were analysed using Student’s t-test for normally distributed data and Mann–Whitney U-test for data that were not normally distributed. Categorical data were compared using χ2-test. Univariate and multivariate logistic regression analyses with decreased and maintained ability to walk as the independent variables were performed. Univariate logistic analysis was performed for all items except for outcome and walking ability at discharge. Multivariate logistic regression analysis was performed using the forced imputation method. A P-value <0.05 was considered statistically significant.
Results
This retrospective observational study screened 333 consecutive patients with aspiration pneumonitis for eligibility. Of these, 143 participants (42.9%) were included in the analysis (Figure 1). The mean ± SD of the overall cohort was 79.7 ± 12.4 years; and 101 patients (70.6%) were male (Table 1). The changes in walking ability from the time of admission to the time of discharge are shown in Table 2.
Flow diagram showing patient selection in a study that examined the factors influencing walking ability among patients hospitalized due to aspiration pneumonia.
Demographic and clinical characteristics of the patients (n = 143) enrolled in a study that examined the factors influencing walking ability among patients hospitalized due to aspiration pneumonia.
Data presented as mean ± SD or n of patients (%).
aFor between-group comparisons, differences in continuous variables were analysed using Student’s t-test for normally distributed data and Mann–Whitney U-test for data that were not normally distributed; categorical data were compared using χ2-test; NS, no significant between-group difference (P ≥ 0.05).
BMI, body mass index; GNRI, geriatric nutritional risk index; BUN, blood urea nitrogen; CRP, C-reactive protein; WBC, white blood cell; SBT/ABPC, sulbactam/ampicillin; CTRX, ceftriaxone; TAZ/PIPC, tazobactam/piperacillin; MEPM, meropenem; FILS, food intake LEVEL scale.
Changes in walking ability before and after hospitalization of the patients (n = 143) enrolled in a study that examined the factors influencing walking ability among patients hospitalized due to aspiration pneumonia.
Data presented as n of patients (%).
*Reduced walking ability after hospitalization due to aspiration pneumonia.
The patients were divided into two groups: those whose walking ability decreased after hospitalization (n = 61) and those whose walking ability was maintained after hospitalization (n = 82). There were significant differences in 15 demographic and clinical characteristics when the two groups were compared (P < 0.05 for all comparisons) (Table 1). There was no significant between-group difference in physical therapy intervention. However, the group with decreased walking ability had significantly higher pneumonia severity based on their A-DROP score (P < 0.001) and a significantly longer time to initial mobilization (P < 0.001) than the group with maintained walking ability. The duration of hospitalization was also significantly longer in the group with decreased walking ability compared with the group with maintained walking ability (P < 0.01).
Univariate logistic regression analysis showed that age, BMI, GNRI score, A-DROP score, total protein, serum albumin, CRP and days to initial mobilization were significantly associated with the ability to walk (Table 3). Multivariate logistic regression analysis was performed using six items as dependent variables among the combinations suspected of showing multicollinearity. BUN and serum albumin were not used as they had high variance inflation factor values. The results showed that A-DROP (odds ratio [OR] 3.006; 95% confidence interval [CI] 1.452, 6.541; P < 0.01), GNRI (OR 0.919; 95% CI 0.875, 0.960; P < 0.001) and days to initial mobilization (OR 1.221; 95% CI 1.036, 1.531; P < 0.05) were independent early predictors of decreased or maintained ability to walk (Table 4).
Univariate logistic regression analysis with decreased ability to walk as the dependent variable using data from the patients (n = 143) enrolled in a study that examined the factors influencing walking ability among patients hospitalized due to aspiration pneumonia.
BMI, body mass index; GNRI, geriatric nutritional risk index; BUN, blood urea nitrogen; CRP, C-reactive protein; WBC, white blood cell; SBT/ABPC, sulbactam/ampicillin; CTRX, ceftriaxone; TAZ/PIPC, tazobactam/piperacillin; MEPM, meropenem; NS, no significant association (P ≥ 0.05).
Multivariate logistic regression analysis with decreased ability to walk as the dependent variable using data from the patients (n = 143) enrolled in a study that examined the factors influencing walking ability among patients hospitalized due to aspiration pneumonia.
VIF, variance inflation factor; SE, standard error; CI, confidence interval; CRP, C-reactive protein; GNRI, geriatric nutritional risk index.
Discussion
The factors influencing walking ability in patients with aspiration pneumonia are yet to be clarified. This current retrospective observational study found that the GNRI score, A-DROP score and days to initial mobilization independently influenced walking ability.
The current study found that the GNRI score is a risk factor for decreased walking ability. GNRI has higher sensitivity for predicting the risk of mortality, infection and pressure ulcers than other nutritional indicators such as serum albumin and BMI. 15 GNRI is stratified into four categories and severe nutritional impairment (defined as GNRI < 82) has the highest risk of nutritional impairment. 12 The maintained walking ability group had a moderate nutritional risk because their mean GNRI score was 84.8, which was between 82 and 92. The decreased walking ability group had a severe nutritional risk because their mean GNRI score was 54.8, which was <82. In the present study, the mean GNRI score of the overall study cohort was <82, indicating that patients that developed aspiration pneumonia had a low nutrition status. Low nutrition is associated with the development, refractoriness and severity of infectious diseases. 22 Low nutritional status decreases acquired immunity (e.g. helper T cell activity and antibody production) 23 and is a risk factor for infections. 22 In addition, there is evidence of higher hospitalization costs and complications in undernourished patients than those with adequate nutrition, 24 indicating the significant impact of undernutrition. It is possible that feeding-related factors may have an impact on patients with aspiration pneumonia. A previous study reported that dysphagia and sarcopenia increased the risk of hyponutrition in the elderly. 25 However, the relationship between the development of aspiration pneumonia and low nutrition has not yet been reported. Thus, it is necessary to demonstrate the relationship between poor nutritional status as measured by the GNRI score and aspiration pneumonia in future studies.
Days to initial mobilization was found to be a risk factor for decreased walking ability in the current study. It is thought that prolonged bed rest results in significant disuse muscle atrophy in skeletal muscles and consequent decline in walking ability. A study on healthy elderly patients on bed rest for 10 days found muscle protein catabolism, loss of lean body mass and weakness of knee extensor muscles. 26 It is thought that the decline in walking ability was caused by a gradual tendency toward muscle protein catabolism as the patient lays in bed after hospitalization; and was also due to inflammatory and drug-related factors. 26 Early mobilization is crucial in preventing disuse syndrome associated with resting and lying in bed. 27 A previous study reported that among elderly patients with aspiration pneumonia and hospitalization-associated disability, 71% did not have improved ADL scores during hospitalization. 28 However, they showed that early rehabilitation significantly improved ADL. 28
Early mobilization of critically ill patients effectively improves exercise tolerance and reduces delirium. 29 For elderly patients with aspiration pneumonia, acute-phase physical rehabilitation programmes generally involve early mobilization, range-of-motion exercises, self-care exercises and muscle strength and endurance training, all of which have the potential to decrease posthospital syndrome and hospital-acquired physical deconditioning. In acute rehabilitation, patients with aspiration pneumonia are instructed to sit in a wheelchair during the daytime. Standing and gait training are introduced according to the condition of the patient. 30 These rehabilitation methods are feasible and effective for almost all geriatric patients with aspiration pneumonia, regardless of the severity of pneumonia. 31
However, early rehabilitation alone is inadequate to improve ADL. As mentioned above, hyponutrition must be taken into consideration. Both rehabilitation and nutrition management are important in geriatric aspiration pneumonia patients with disability and malnutrition. Nutrition status is associated with rehabilitation outcomes in geriatric patients with hospitalization-associated disability. 32 Further, nutritional deficiencies can promote muscle catabolism. 33 This could explain the current findings that the GNRI score, which is related to nutrition, and days to initial mobilization, which is related to early mobilization, were risk factors for decreased walking ability. The concept of rehabilitation nutrition as a combination of rehabilitation and nutrition care management proposed by the International Classification of Functioning, Disability and Health guidelines is used to evaluate the nutrition status and maximize functionality among the elderly and other individuals with disability. 34
There are also advantages to bed rest, such as the protection of metabolic function for healing, reduction of muscle oxygen consumption and reduction of stress on the heart. 29 However, it should be noted that the degree to which early bed release should be promoted should be considered along with disadvantages such as the progression of disuse syndrome. 29 The severity of illness was an important influencing factor. The A-DROP score is a modified version of the CURB-65 score proposed by the Japanese Respiratory Society in 2006. 18 The severity of the disease increases the duration of time taken to treat the disease, which in turn increases the duration of time taken to release the patient from the bed.
There was a significant difference in FILS at discharge between the two groups in the current study. The FILS is practical tool for assessing the severity of dysphagia. Recent studies have reported an association between swallowing impairment and physical disability as well as malnutrition in the elderly.35,36 Since FILS at discharge may reflect the results of treatment and rehabilitation, future studies should be conducted in detail using preadmission FILS.
This current study had several limitations. First, it was a single-centre study. Secondly, due to its retrospective nature, only data at the time of hospitalization were collected. Data from multi-centre, prospective studies are needed to improve the care and rehabilitation of the increasing number of patients with aspiration pneumonia. Thirdly, this study did not evaluate other diseases or disabilities other than dementia and hemiplegia. There may have been other comorbidities that affected the ability to walk.
In conclusion, the GNRI score, A-DROP score and days to initial mobilization were independent risk factors for decreased walking ability in patients hospitalized due to aspiration pneumonia. These results suggest that nutritional status and early mobilization are important factors affecting the maintenance of walking ability in these patients. Thus, a combination of nutrition and early rehabilitation may be necessary as a treatment strategy for patients with aspiration pneumonia.
Research Data
Research Data for Risk factors for decreased walking ability in hospitalized patients with aspiration pneumonia
Research Data for Risk factors for decreased walking ability in hospitalized patients with aspiration pneumonia by Yorihide Yanagita, Shinichi Arizono, Yuichi Tawara, Masaki Oomagari, Hikaru Machiguchi, Koshi Yokomura, Norimasa Katagiri and Yuki Iida in Journal of International Medical Research
Footnotes
Acknowledgements
We are grateful to all the patients for their cooperation with the study. We also thank the physicians, physical therapists and all staff that acquired data for the study.
Author contributions
Conceptualization: Y.Y., S.A., Y.I.; data curation: Y.Y., M.O., H.M., K.Y.; formal analysis: Y.Y., S.A., M.O., H.M., Y.I.; funding acquisition: Y.Y., Y.I.; investigation, Y.Y., M.O., H.M.; methodology: Y.Y., S.A., Y.I.; project administration: Y.Y., S.A., Y.I.; resources, Y.Y., K.Y.; supervision, S.A., Y.T., K.Y., N.K., Y.I.; software: Y.Y.; validation, Y.Y., S.A., Y.I.; writing – original draft: Y.Y.; writing – review & editing: S.A., Y.T., M.O., H.M., K.Y., N.K., Y.I.
Declaration of conflicting interests
Shinichi Arizono reports grants from Hoshi Iryo-Sanki Co. Ltd and NPO Central Japan Lung Study Group outside the submitted work. All other authors declare that they have no competing interests.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was funded by the Toyohashi Sozo University Fund for Domestic and Overseas Research Support, 2022.
References
Supplementary Material
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