Heart rate variability in individuals with Down syndrome - A systematic review and meta-analysis.

INTRODUCTION

Down syndrome (DS) results in many changes, including dysfunction in cardiac autonomic modulation. Heart rate variability (HRV) analysis evaluates the autonomic function and it is a predictor of adverse cardiovascular events.

OBJECTIVE

To present results of a systematic review and a meta-analysis about heart rate variability in individuals with DS.

METHOD

A systematic review was performed on PubMed, PubMed Central and Web of science databases. We included articles that exhibited all the terms: "Down Syndrome", "heart rate variability", "autonomic nervous system", "autonomic dysfunction" and "cardiac autonomic modulation". We conducted the meta-analysis to compare "DS" to "controls" during rest. Random effects models were used, as were appropriate tests for heterogeneity.

RESULTS

From 271 studies, 13 were included in our review. These are conducted with volunteers from a wide age range, of either gender, and not taking medications. Meta-analysis displayed that there were no significant differences between the groups at rest, except the RMSSD, which revealed a significant (Z = -2.80, p = 0.005) main effect (Hedge's g = -0.55, 95% CI [-0.93; -0.16]), indicating difference in individuals with DS compared with controls.

CONCLUSION

There is autonomic dysfunction in individuals with DS, which may or may not be expressed at rest, but it is usually demonstrated in an autonomic task. Meta-analysis specified that there was no significant alteration between DS and the controls during rest, except RMSSD index which was lower in DS than controls.

PROSPERO

CRD42017068647.