Heart rate variability as a potential biomarker for alcohol use disorders: A systematic review and meta-analysis

Background: Alcohol use disorders (AUDs) have been found to be associated with elevated cardiovascular risk. The autonomic nervous system is considered to play a role in this association. Heart rate variability (HRV) has been employed to measure parasympathetic activity in AUDs patients in some studies; however, the results are not consistent, and the adopted HRV indices vary across studies. A meta-analysis should be helpful for clarifying this topic. Methods: We gathered studies about measuring HRV in AUDs patients and healthy participants from databases. HRV was analyzed in several ways: parasympathetic function in hierarchical order (main analysis), total variability, and specific parasympathetic indices. Specific parasympathetic indices were further separated into high-frequency power (HF) and root mean square of the successive differences (RMSSD). For comparing the above values in patients with AUDs and in healthy individuals, we adopted the random effects model to calculate the standardized mean difference. Results: Of the 144 screened studies, 15 were included in the quantitative analysis. In the comparison of parasympathetic function in hierarchical order, HRV in AUDs patients was significantly lower than in healthy individuals (Hedges'g = -0.4301, 95% CI [-0.7601 to -0.1000], p=0.0106, I-2 = 83.8%). Regarding total variability and RMSSD, AUDs patients also had significantly lower values than healthy controls. However, the differences of specific parasympathetic indices and HF were not significantly different. Conclusion: Our results support the view that AUDs patients have reduced parasympathetic activity. Total variability and RMSSD are suitable indices for presenting reduced HRV in patients with AUDs.