Heart rate variability and the short form-8 Japanese version for health-related quality of life in the general Japanese population

Self-rated health predicts mortality. Autonomic dysfunction is thought to be a relevant biological mechanism but has not been investigated in the general population. A cross-sectional study was conducted on 5,908 Japanese men and women aged 30-79 years old. As an autonomic function, heart rate variability (HRV) was assessed using five minute-recordings of pulse waves with a fingertip sensor, and the time and frequency domains of HRV were determined. Health-rated quality of life (HRQOL) was assessed by using the Short Form-8 Japanese version, and poor HRQOL was defined as <50 scores of sub-scales. A test for nonlinear trends was performed in the generalized additive model with the smoothing spline adjusted for confounders. The impact on poor physical component score increased in those who had lower levels of the standard deviation of normal-to-normal intervals (SDNN) and the root mean square of successive difference (RMSSD), and the high frequency (HF) power and tended slightly upward in the higher levels as well. HRV parameters were nonlinearly associated with poor physical component. Reduced SDNN, RMSSD, and HF, which reflect parasympathetic modulations, were associated with poor HRQOL in the domain of physical function. Also, higher levels of these did not necessarily translate into better HRQOL.