This was a retrospective, cohort study of inpatients admitted to a community-based hospital and a teaching hospital in Japan from January 2015 to December 2018. This study was approved by the institutional review boards of the hospitals and conformed to the provisions of the Declaration of Helsinki (as revised in Brazil 2013).
Definitions
FS was evaluated at admission and before discharge by the Barthel Index (BI) [8] (range, 0–100, in 5-point increments) of ADL and was graded into three categories according to the BI: independent, BI 80–100; semi-dependent, BI 30–75; and dependent, BI 0–25 [9]. A decreased FS was considered a reduction in ADL of at least one category. Disorder of conscious (DOC) was defined as a Glasgow Coma Scale [10] score below 15, and for dementia patients, DOC was considered only if their consciousness was worse than their normal status. The key person (representing the main individual supporting the patient during and after admission) was classified as a child, spouse, or others. Rehabilitation included any type and intensity of physical rehabilitation program administered by physicians, physical therapists, and occupational therapists. The need for rehabilitation was determined during admission based on the risk of disuse syndrome or aspiration pneumonia. For survival patients, sites of acquisition were classified as home discharge (without nursing), home nursing, facility and transfer to another hospital.
Patients
Elderly hospitalized CAP patients were divided into two groups: maintained group, without deterioration of FS; and decreased group, with decreased FS. All enrolled cases had been diagnosed with CAP according to the definitions of the American Thoracic Society/Infectious Diseases Society of America guideline [11]. Patients who fulfilled all of the following inclusion criteria were enrolled in the study: 1) age >64 years; 2) symptoms compatible with pneumonia (e.g., fever, cough, sputum, pleuritic chest pain, or dyspnea); and 3) appearance of new pulmonary infiltrates consistent with pneumonia on chest X-ray or computed tomography. To ensure that all eligible cases were enrolled, the study investigators screened the hospital database for International Classification of Diseases, 10th revision (ICD-10) codes (J13-18, J69) and reviewed hospital medical records. Repeated episodes of pneumonia in the same patient within a 2-week period were regarded as a single episode.
Exclusion criteria
Cases of healthcare-associated pneumonia (HCAP) and hospital-acquired pneumonia (HAP) were excluded [12]. Cases with complications that occurred during admission (myocardial infarction, femoral fracture, cerebral infarction, etc.) that would have affected FS were also excluded.
Outcomes
The primary outcome was the effect of rehabilitation in preventing decreased FS. Demographic information, vital signs, including DOC and body mass index (BMI), laboratory values, and comorbidities were collected on admission. Comorbidities were identified according to the Charlson Comorbidity Index (CCI) [13]. The Pneumonia Severity Index (PSI) [14] score was calculated based on data obtained at the time of admission. Information regarding the key person was confirmed soon after admission. Information about acquisitions for survivors was also collected, and all patients who died were considered in-hospital deaths. Information of medical costs were collected at discharge.
Statistical analyses
The results are presented as numbers and percentages or medians and interquartile ranges unless otherwise indicated. Groups were compared using Wilcoxon rank-sum tests. In order to evaluate the effect of rehabilitation on FS, risk factors for decreased FS were determined using stepwise regression analysis. Confounding variables of decreased FS, age, sex, BMI, aspiration, dementia, DOC, undergoing rehabilitation, pre-admission ADL, PSI, CCI, and LOS were chosen as candidates with p values below 0.2 on univariable analysis. Using the model of the minimum corrected Akaike’s information criterion (AICc) in the backward direction, the final variables were determined. The effect of rehabilitation was evaluated by propensity score analysis by adjustment with variables determined on multivariable analysis. McNemar’s test was performed to evaluate the effect of rehabilitation on preventing decreased FS in matched pairs. In all instances, two-tailed values of p<0.05 were considered significant. Data analysis was performed using JMP software (version 15.0; SAS Institute, Cary, NC).