The frail scale combined with PNN50: a new direction for screening cardiovascular risks in the elderly

Heart rate variability (HRV) is a clinically relevant, noninvasive biomarker for autonomic function and cardiovascular disease (CVD) risk in the elderly. However, the link between frailty scales and HRV parameters, and their combined predictive value for frailty progression and CVD outcomes in geriatric patients, remain unclear. This study investigated associations between frailty status and HRV parameters and aimed to develop an integrated Frail scale-HRV assessment for evaluating both frailty progression and CVD risk in advanced-age elderly. A total of 498 consecutively hospitalized participants aged ≥ 80 years were included in the final analysis. Eligible individuals were stratified into two mutually exclusive groups using the validated FRAIL scale: non-frail (robust and pre-frail) older adults (scores < 3), and frail older adults (scores ≥ 3). All participants completed 24-hour Holter ECG monitoring, with a panel of standardized cardiovascular parameters collected in parallel during the monitoring period. A distinct U-shaped association was observed between frailty severity and HRV parameters (RMSSD, PNN50) in octogenarians. PNN50 emerged as an independent risk factor for frailty, with restricted cubic spline analysis pinpointing a clinically meaningful threshold at 37.4% (peak OR = 3.3). These findings support combining PNN50 with the FRAIL scale to optimize cardiovascular risk stratification in hospitalized very elderly patients. We identified a U-shaped association between frailty severity and HRV time-domain parameters (PNN50, RMSSD) in octogenarians. The independent association between elevated PNN50 and greater frailty severity supports the potential utility of integrating PNN50 into the FRAIL scale to improve cardiovascular risk prediction in geriatric clinical practice.