Meta-analysis of the association between body mass index and health-related quality of life among adults, assessed by the SF-36.

Objective: Obesity is associated with impaired overall health-related quality of life but individual studies suggest the relationship may differ for mental and physical quality of life. A systematic review using Medline, Embase, PsycINFO and ISI Web of Knowledge, and random effects meta-analysis was undertaken.
Design and Methods: Studies were included in the meta-analysis if they were conducted on adults (defined as age >16 years), reported an overall physical and mental component score of the SF-36, and, or both. Heterogeneity was assessed using I(2) statistics and publication and small study biases using funnel plots and Egger's test. Between-study heterogeneity was explored using meta-regression.
Results: Eight eligible studies provided 42 estimates of effect size, based on 43,086 study participants. Adults with higher than normal body mass index had significantly reduced physical quality of life with a clear dose-response relationship across all categories. Among class III obese adults, the score was reduced by 9.72 points (95% Confidence Interval 7.24, 12.20, P < 0.001). Mental quality of life was also significantly reduced among class III obese (-1.75, 95% confidence interval -3.33, -0.16, P = 0.031), but was not significantly different among obese (class I and class II) individuals, and was significantly increased among overweight adults (0.42, 95% confidence interval 0.17, 0.67, P = 0.001), compared to normal weight individuals. Heterogeneity was high in some categories, but there was no significant publication or small study bias.
Conclusions: Different patterns were observed for physical and mental HRQoL, but both were impaired in obese individuals. This meta-analysis provides further evidence on the impact of obesity on both aspects of health-related quality of life.
(Copyright © 2013 The Obesity Society.)