Motivational theory-based interventions on health of people with several mental illness: A systematic review and meta-analysis.

Motivational theory-based interventions are known to be effective for increasing physical activity (PA) in the general population but their effects in people with severe mental illness are poorly understood. Therefore, we conducted a meta-analysis on the effect of these interventions on PA and cardiometabolic risk factors. A systematic search of randomized controlled trials through 6 databases was carried out from inception to March 2019. Analyses were conducted using random-effect models. Weighted mean difference (WMD) were used as effect size when outcomes had the same units, otherwise Hedge's g was used. Fourteen articles including 2128 participants were identified. Motivational theory-based interventions were effective in increasing PA (g = 0.27, 95%CI[0.03; 0.51], p = .003), reducing weight (WMD = -1.87 kg, 95%CI[-2.98; -0.76], p = .001), body mass index (WMD = -0.82 kg/m2, 95%CI[-1.23; -0.41], p = .009), waist circumference (WMD = -1.91 cm, 95%CI[-3.63; -0.18], p = .03) and fasting glucose (g = -0.17, 95%CI[-0.34; -0.001], p = .04). Larger effect sizes were found in interventions based on only one theoretical model of motivation. In conclusion, interventions using motivational theories are effective to improve PA levels and the cardiometabolic health profile of people with severe mental illness. Systematic review registration: CRD42018104445.