Smartphone-measured heart rate variability and quality of life in patients with gynecological cancer: a multicenter prospective study

In this study, we aimed to investigate the association between heart rate variability (HRV) and quality of life (QoL) in patients with gynecological cancer and examine whether continuous HRV monitoring may help identify QoL deterioration. This multicenter, prospective, observational study screened 215 patients with gynecological cancer undergoing chemotherapy at five designated cancer hospitals. Participants measured HRV with a smartphone application for 1 min daily and completed patient-reported outcomes every 1–2 weeks for 10 weeks. The primary outcome was overall QoL (Global Health Status [GHS]), and the discriminative performance of HRV parameters for lower GHS was evaluated using the area under the receiver operating characteristic curve. Changes in HRV were evaluated at the time of a 10-point decrease in GHS or a 7-point reduction in the FACT-G total score over 7 days. We analyzed 2880 data points from 85 patients. The root mean square of successive differences (rMSSD), a parasympathetic HRV parameter, and the low frequency/high frequency ratio, an index of autonomic balance, demonstrated moderate to high discriminative performance in classifying GHS level. In exploratory within-individual analyses, the rMSSD significantly declined from the preceding week to the week of GHS deterioration and FACT-G total score deterioration. Although these findings may not be generalizable to patients with limited digital literacy, smartphone-based HRV was associated with clinically meaningful QoL deterioration, suggesting that low-burden HRV monitoring may complement patient-reported QoL assessment in patients with cancer.