Autonomic functioning in irritable bowel syndrome measured by heart rate variability: A meta‐analysis

Objective To analyze autonomic functioning which presented as the high frequency ( HF ) component of heart rate variability, a measurement of vagal tone, and the ratio of low frequency ( LF ) to HF (LF : HF), an indicator of sympathovagal balance in irritable bowel syndrome ( IBS) patients. Methods We identified relevant studies by performing a literature search of MEDLINE , EMBASE and the ISI Web of Knowledge to 31 M arch 2013. Pooled effect sizes with 95% confidence interval ( CI ) were calculated using a random effects model. Between‐study heterogeneity was assessed using the Q test and I 2 statistic. Results In all, 11 articles including 392 IBS patients and 263 controls met the inclusion criteria of the analysis. IBS patients had lower HF band power ( H edges's g = −0.38, 95% CI −0.68 to −0.09) than the controls ( I 2  = 63.6%, P  = 0.003). Moreover, IBS patients showed a higher LF  :  HF ( H edges's g = 0.43, 95% CI 0.13–0.74), with no significant heterogeneity. A subgroup analysis of the HF index according to the recording time yielded different results for the IBS patients and controls. Additionally, constipation‐predominant IBS ( IBS ‐ C ) patients had decreased HF band power, whereas no significant difference was found in LF  :  HF . Conclusions Impaired parasympathetic functioning and abnormal sympathovagal balance may be involved in the pathogenesis of IBS . Vagal dysfunction is more obvious in the IBS ‐ C subgroup.