Reliability of resting-state photoplethysmogram-based pulse rate variability in lifespan samples: implications for cardiovascular research.

Objective.Pulse rate variability (PRV), derived from photoplethysmography, offers a scalable approach to studying cardiac autonomic regulation. However, the reliability of PRV measures across human lifespan has not been systematically evaluated, limiting their application in cardiovascular research.Approach.Pulse wave data of 914 healthy young subjects from the Human Connectome Project (HCP) young adults were analyzed. PRV was derived from four 15 min resting-state functional MRI sessions using NeuroKit2. Reliability of 86 PRV metrics across time, frequency, and nonlinear domains was assessed using intraclass correlation coefficients (ICCs). Findings were validated in independent HCP developmental (HCP-D;n= 536; ages 5-21) and HCP aging (HCP-A;n= 652; ages 36-100+) cohorts to evaluate lifespan generalizability. Sex-specific and race-specific analyses were also performed.Main results.We analyzed 914 healthy young adults (mean age 28.7 ± 3.7 years;n= 489, 53.5% female;n= 425, 46.5% male), of whom 75.6% self-identified as White, 13.1% as African American, and 11.3% as other. Of 86 PRV metrics, 62 (72.1%) showed excellent reliability (ICC ⩾ 0.75) across all four sessions spanning two days, with higher stability within-day than across days. Time-domain measures (e.g. Prc80NN, pNN20, MeanNN, MedianNN) and nonlinear measures (e.g. ShanEn, IALS, and PSS) were highly reliable with ICC ⩾ 0.90. In the frequency domain, HFn and LFn performed best (ICC ⩾ 0.85). The reliability patterns were highly consistent across developing and aging cohorts and were broadly similar across sex and race subgroups among highly reliable PRVs.Significance.A substantial proportion of PRV metrics showed excellent reliability across the lifespan, with broadly similar patterns across sex and racial groups, supporting their use in research settings.