Effectiveness of the frailty index in predicting recurrent pneumonia and death in long-term hospitalized patients with vascular cognitive impairment

Objective

The aim was to predict the effectiveness of using frailty, defined by the frailty index (FI), for predicting recurrent pneumonia and death in patients over 50 years and older with vascular cognitive impairment (VCI) during long-term hospitalization.

Measurements

This retrospective cohort study was conducted at a teaching hospital in western China and included VCI patients aged ≥50 years undergoing long-term hospitalization. The relevant data were collected from the electronic medical record system. The FI was based on 31 parameters and groups were defined using a cutoff value (0.2) as robust (FI < 0.2) and FRAIL (≥0.2). The definition of recurrent pneumonia was a minimum of two episodes within a year, with the symptoms, signs, and imaging results of pneumonia disappearing completely between episodes, and a minimum interval between episodes of seven days. Death was recorded by the hospital as the result of cardiac and respiratory arrest and survival was defined as the interval between hospital admission and confirmed death. Logistic regression models were used to assess the association between FI and recurrent pneumonia, while associations between FI and death were assessed by Cox proportional hazards models.

Results

A total of 252 long-term hospitalized VCI patients ≥50 years old were enrolled, of whom 115 were male (45.6 %). Ninety-seven patients (38.5 %) were defined as FRAIL. The median length of stay for hospitalized patients was 37 months. Overall, 215 patients developed pneumonia during hospitalization, which occurred an average of 14.5 months after admission, while 151 (59.9 %) had recurrent pneumonia, and 155 (61.5 %) died. Of these, 143 died in the hospital and 12 died after discharge. No significant differences were seen in the incidence of recurrent pneumonia between FRAIL and robust long-term hospitalized VCI patients (FRAIL vs. robust: 66.0 % vs. 56.1 %, P = 0.121) while FRAIL patients had a higher mortality rate than robust patients (FRAIL vs. robust: 71.1 % vs. 55.5 %, P = 0.013). After further Cox regression analysis and adjustment for possible confounders found to be significant in the univariate analysis (including age, sex, smoking history, and activities of daily living (ADL) score), FRAIL patients had a higher risk of death than healthy patients (HR = 1.595, 95 % CI: 1.149–2.213). In addition, based on Model 2, confounding variables that were not statistically significant in the univariate analysis but may have had an impact on the results (including marital status, educational level, drinking history, comorbidity and rehabilitation treatment) were incorporated into Model 3 for further correction. The result remained unchanged, namely, that compared with robust patients, FRAIL patients had a higher risk of death (HR = 1.771, 95 % CI: 1.228–2.554).

Conclusions and implications

Frailty defined by the FI was effective for predicting the risk of mortality but not that of recurrent pneumonia in long-term hospitalized VCI patients aged 50 or older.