Heart rate variability in patients with somatic symptom disorders and functional somatic syndromes: A systematic review and meta-analysis

This research is aimed to systematically review heart rate variability (HRV) findings of functional somatic syndromes (FSSs) and somatic symptom disorders (SSDs), and to compare the HRV values between FSSs/SSDs patients and healthy individuals. We included clinical studies assessing HRV (including baseline HRV and HRV reactivity) in FSSs/SSDs and healthy participants. We searched PubMed, Embase, PsycINFO, MEDLINE, and Web of Science databases from the earliest available date to June 2019. Eighty-five studies comprising 3242 FSSs/SSDs patients and 2321 controls were included in the main meta-analysis; the baseline HRV value was significantly lower compared to healthy individuals (Hedges'g, -0.43; 95 % CI, -0.54 to -0.30; p < .001), with the largest effect size in fibromyalgia patients. A significant lower HRV was also found for total variability (Hedges'g, -0.56; 95 % CI, -0.77 to -0.36) and specific parasympathetic indices (Hedges'g, -0.41, 95 % CI; -0.54 to -0.30). HRV reactivity was significantly lower in FSSs/SSDs patients (Hedges'g, -0.42; 95 % CI, -0.64 to -0.20). Our results support the notion that FSSs/SSDs patients have significantly lower HRV than healthy individuals.