Body mass index in Parkinson's disease: a meta-analysis.

Prior work suggested that patients with Parkinson's disease (PD) have a lower Body Mass Index (BMI) than controls, but evidence is inconclusive. We therefore conducted a meta-analysis on BMI in PD. We searched MEDLINE, EMBASE, Cinahl and Scopus to identify cohort studies on BMI in PD, published before February 2011. Studies that reported mean BMI for PD patients and healthy controls were eligible. Twelve studies were included, with a total of 871 patients and 736 controls (in three studies controls consisted of subjects from other published studies). Our primary aim was to assess differences in BMI between patients and controls; this was analyzed with random effects meta-analysis. Our secondary aim was to evaluate the relation with disease severity (Hoehn and Yahr stage) and disease duration, using random effects meta-regression. PD patients had a significantly lower BMI than controls (overall effect 1.73, 95% CI 1.11-2.35, P<0.001). Pooled data of seven studies showed that patients with Hoehn and Yahr stage 3 had a lower BMI than patients with stage 2 (3.9, 95% CI 0.1-7.7, P<0.05). Disease duration was not associated with BMI. Because a low body weight is associated with negative health effects and a poorer prognosis, monitoring weight and nutritional status should be part of PD management.