In the present study we examined the influence of heart failure comorbidity on the efficacy of rehabilitation in patients with hospitalization-associated disability after AP in a convalescent rehabilitation ward. Heart failure was defined according to the Guidelines of the Japanese Heart Failure Society [30]. Assessment of the clinical characteristics of the patients with AP with comorbid heart failure revealed them to be older; to be more likely to have other comorbidities; and to have lower hemoglobin levels than patients without heart failure. On the other hand, there were no significant differences in ADL indices, swallowing function or nutritional condition at admission between the two groups. In addition, rehabilitation outcomes were significantly lower in patients with AP with comorbid heart failure than in those without heart failure. REs significantly correlated to gender, handgrip strength, quadriceps strength, FOIS, MNA-SF and BNP. Multiple regression analysis showed that gender, quadriceps strength, MNA-SF and BNP were independently associated with REs, while gender, handgrip strength, MNA-SF, and BNP were independently associated with gait acquisition. These results suggest that heart failure comorbidity has a significant negative effect on rehabilitation in patients with hospitalization-associated disability after AP.
In recent years, pneumonia among the elderly has been increasing in developed countries [33]. Aspiration is the most common cause of pneumonia in the elderly [3], and it has been reported that AP significantly increases 30-day mortality [34]. According to the annual report from Ministry of Health, Labour and Welfare in Japan in 2021 [2], more than 70,000 people die each year from pneumonia, making pneumonia the fourth leading cause of death. Among those who die from pneumonia, 96% are 70 years of age or older.
Hospitalization is a common risk for a variety of adverse health events [35]. Among them, functional decline is a common and serious hospitalization-associated problem that results in a decrease in quality of life and lifestyle, especially in older patients [10, 36]. Previous studies have shown that 30–60% of older people develop new dependencies for ADL during their hospital stay [36, 37]. An earlier study showed that in the elderly this decline in physical function during hospitalization significantly associates with pneumonia and that it takes a long time for these patients to return home and regain function [38]. Thus, patients with pneumonia have a significant decline in ADL during hospitalization, which makes it important to understand what factors are associated with the decline in physical function during hospitalization for pneumonia. Kato et al. [38] previously reported that age, history of cerebrovascular disease, and aspiration are potential risk factors for ADL decline in patients following pneumonia. In the present study, we performed rehabilitation in elderly patients after treatment for AP. The mean age at admission was 82 years, and the mean Barthel Index score at admission of 26 ± 24, which is consistent with the mean Barthel Index score of 22 previously measured at admission for a nursing health care-associated pneumonia (NHCAP) group [38]. In the present study, rehabilitation therapy in patients with hospitalization-associated disability following AP led their Barthel Index scores to improve to an average of 23 ± 26. An earlier retrospective study using the Diagnosis Procedure Combination (DPC) database in an acute care hospital showed that early intervention with physical therapy in patients with AP improved ADL measures as compared to a no intervention group [13]. However, the improvement in Barthel Index score was 7.2 versus 6.9, which is a significant (p < 0.001) but small difference, and the absolute improvement was less than what we obtained. This difference between the two studies is probably due to the difference between acute care and convalescent hospitals. In fact, the length of the hospital stay was much shorter in acute care hospitals, 30 days in the rehabilitation group and 28 days in the non-rehabilitation group. By contrast, our median stay was 84 days. This suggests that even patients with AP can improve their ADL to some extent if they receive adequate daily rehabilitation for approximately 80 days.
We used REs as a measure of rehabilitation effectiveness. In the present study, quadriceps strength, MNA-SF, BNP and gender were independently and significantly associated with REs. This indicates that poor nutrition, poor muscle strength, the presence of heart failure comorbidity and male sex diminish the effectiveness of rehabilitation. It is well known that poor nutrition and muscle strength on admission negatively affect rehabilitation effectiveness [11]. Moreover, sarcopenia and frailty are often observed in elderly heart failure patients and accompany muscle weakness that diminishes beneficial rehabilitation effects [40]. We recently reported that the presence of heart failure, as assessed from plasma BNP concentrations (> 100pg/mL), attenuates rehabilitation effectiveness in elderly patients with hip fracture [15, 16]. The results of the present study extend those findings to patients with AP. This is important because heart failure can be managed with appropriate guideline-directed medical therapy [19]. In addition, a prior diagnosis of heart failure can help reduce risks during rehabilitation by alerting physical therapists that perform rehabilitation to pay attention for changes in blood pressure, heart rate, chest pain and arrhythmias.
The ability to walk independently is one of the most basic ADL. One of the causes of loss of independent walking is hospitalization due to acute illnesses, including heart disease and respiratory illnesses such as pneumonia [40]. Previous studies showed that the incidence of ambulatory dependence was 17–59% of patients hospitalized for acute illness [40, 41]. Restoring the ability to walk independently is important because reduced ambulation is associated with falls, fractures, death, and nursing home placement [42]. Therefore, determining factors associated with gait recovery is important for rehabilitation. In this study, MNA-SF, handgrip strength, and plasma BNP at admission were significantly associated with recovery of independent walking at discharge. These findings indicate that poor nutritional status, generalized muscle weakness and heart failure on admission to a convalescent hospital are all negatively associated with gait gain at discharge. However, because this study was not interventional, we cannot suggest that there are causal relationships among nutritional index, systemic muscle weakness and concomitant heart failure and the failure to walk independently after discharge. Future research will be necessary to determine whether muscle strength training with nutritional improvement and treatment of heart failure will lead to improved walking ability.
We used plasma BNP levels as a surrogate marker for a diagnosis of heart failure. BNP is a hormone produced and secreted by the heart [43] and is known to be increased not only in heart failure but also in left ventricular hypertrophy [44], acute myocardial infarction [45], right ventricular hypertrophy associated with pulmonary hypertension [46], coronary artery disease [47] and renal failure [48]. Previous studies showed that a cut-off value of 100 pg/mL has a high negative predictive value for a diagnosis of heart failure [49]. On the basis of guidelines from the Japan Heart Failure Society, patients with a plasma BNP level ≥ 100 pg/mL were defined as having heart failure in the present study. We previously showed that rehabilitation is attenuated in hip fracture patients diagnosed with heart failure based on plasma BNP ≥ 100 pg/mL and that nutritional disorders and heart failure are additively associated with the attenuated rehabilitation effect [15, 16]. Our present results are consistent with those earlier findings.
A diagnosis of heart failure is usually based on medical history, physical examination, electrocardiogram, chest X-ray and echocardiographic findings, among other parameters. Consequently, specialized knowledge and skills are required to make a diagnosis. By contrast, plasma BNP levels are easily measured and have been shown to more predictive of heart failure than the aforementioned tests [49]. In a super aging society, the number of patients with heart failure is increasing [14], as is the number of patients with comorbid heart failure in the convalescent wards. When latent heart failure is overlooked, acute heart failure often develops during rehabilitation, necessitating transfer of the patient to an acute care hospital. By not overlooking diagnosed latent heart failure, rehabilitation can be performed under the appropriate drug therapy. At our hospital, the number of patients who develop acute heart failure during their stay has nearly disappeared since we introduced BNP testing to screen patients admitted to the convalescent rehabilitation ward. Plasma BNP measurements are therefore considered useful biochemical tests for heart failure screening on admission to convalescent rehabilitation wards.
In conclusion, these results suggest that muscle strength and nutritional condition at admission are related to the rehabilitative effects and gait acquisition in patients with hospitalization-associated disability after AP. In addition, heart failure comorbidity, assessed based on plasma BNP level, may negatively affect rehabilitative effects and gait acquisition.