Association between Physical Activity and the Risk of Mortality and Hospitalization in Older Korean Adults with Heart Failure

Abstract

Background: Regular exercise improves the functional ability and quality of life of patients with heart failure (HF). However, studies on the results of intensity of exercise in the older population are scarce, especially in the Asian population.

Method and results: A total of 8982 older people (age $\ge$ 65 years) with HF were selected from the Korean National Health Insurance Service-Senior database (2005-2012). Participants were stratified according to the levels of physical activity per week as follows: (1) inactive group; (2) insufficiently active group: 1-499 metabolic equivalent task minutes (MET-min)/week; (3) active group: 500-999 MET-min/week; and (4) highly active group: $\ge$ 1000 MET-min/week. During a median follow-up period of 3.2 years, the incidence and risk of mortality were reduced in the insufficiently active (6.7 vs. 4.2 per 100 person-years, adjusted hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.71-0.94; p $<$ 0.001), active (3.8 per 100 person-years; HR, 0.81; 95% CI, 0.70-0.95; p = 0.010), and highly active (2.4 per 100 person-years; HR, 0.52; 95% CI, 0.41-0.67; p $<$ 0.001) groups compared to inactive patients.

Conclusions: In older Asians with HF, increased physical activity reduced the risk of all-cause mortality. The mortality-reducing benefit started at a lower physical activity compared to the World Health Organization guideline (500-999 MET-min/week), and the risk decreased with more physical activity.

Keywords: exercise; heart failure; physical activity.

Fig. 1.

Flow diagram of the study population. A total of 8982 heart failure patients aged 65 years or older in Korea were classified according to exercise intensity.

Fig. 2.

Weekly level of physical activity and adjusted hazard ratio for all-cause hospitalization in older adults with heart failure. MET, metabolic equivalent task. Non-linear cubic spline curve of weekly physical activity level against hospitalization. Black line represents the fitted line of the association between weekly physical activity level and adjusted hazard ratio of hospitalization, whereas the shaded region represents the 95% confidence interval.

Fig. 3.

Subgroup analyses of all-cause mortality in older adults with heart failure. AF, atrial fibrillation; CI, confidence interval; DM, diabetes mellitus; HF, heart failure; HTN, hypertension; PYR, person-years at risk. Forest plot showing the adjusted hazard ratios of all-cause death in older (age $\ge$65 years) patients with heart failure. In all cases of HF, regardless of the presence or absence of DM, HTN, AF, and stroke, exercise reduced all-cause mortality. Even minimal exercise reduced all-cause death compared to no exercise, and the degree of mortality reduction increased as the level of exercise increased.

Fig. 4.

Adjusted hazard ratio for all-cause mortality in older adults with heart failure by weekly physical activity levels. MET, metabolic equivalent task. Non-linear cubic spline curve of physical activity level against all-cause mortality. Black line represents the fitted line of the association between weekly physical activity level and adjusted hazard ratio of mortality, whereas the shaded region represents the 95% confidence interval.