Correlation between health-related quality of life in the physical domain and heart rate variability in asymptomatic adults

Background: Reduced health-related quality of life in the physical domain (HRQOL_physical) has been reported to increase risks for cardiovascular disease (CVD); however, the mechanism underlying this phenomenon is still unclear. The autonomic nervous system (ANS) that connects the body and mind is a biologically plausible candidate to investigate this mechanism. The aim of our study is to examine whether the HRQOL_physical independently contributes to heart rate variability (HRV), which reflects ANS activity. Methods: We recruited 329 physically and mentally healthy adults. All participants completed Beck Anxiety Inventory, Beck Depression Inventory and World Health Organization Questionnaire on Quality of Life: Short Form-Taiwanese version (WHOQOL-BREF). They were divided into groups of individuals having high or low scores of HRQOL_physical as discriminated by the quartile value of WHOQOL-BREF. We obtained the time and frequency-domain indices of HRV, namely variance (total HRV), the low-frequency power (LF; 0.05-0.15 Hz), which may reflect baroreflex function, the high-frequency power (HF; 0.15-0.40 Hz), which reflects cardiac parasympathetic activity, and the LF/HF ratio. Results: There was an independent contribution of HRQOL_physical to explaining the variance in HRV after excluding potential confounding factors (gender, age, physical activity, alcohol use, depression and anxiety). Compared with the participants with high levels of HRQOL_physical, those with low levels of HRQOL_physical displayed significant reductions in variance and LF. Conclusions: This study highlights the independent role of low HRQOL_physical in contributing to the reduced HRV in healthy adults and points to a potential underlying mechanism for HRQOL_physical to confer increased risks for CVD.