Relation of health-related quality of life to metabolic syndrome, obesity, depression and comorbid illnesses

Background: Metabolic syndrome has been associated with impaired health-related quality of life (HRQoL) in several studies. Many studies used only one HRQoL measure and failed to adjust for important confounding variables, including obesity, depression and comorbid conditions. Objective: To investigate the relationship between metabolic syndrome and HRQoL using multiple measures. We also sought to determine whether increasing body mass index or diabetes status further modified this relationship. Methods: This cross-sectional study included 390 obese participants with elevated waist circumference and at least one other criterion for metabolic syndrome. Of these 390 participants, 269 had metabolic syndrome (that is, they met 3 out of the 5 criteria specified by the NCEP (National Cholesterol Education Program)) and 121 did not. Participants were enrolled in a primary care-based weight-reduction trial. HRQoL was assessed using two generic instruments, the Medical Outcomes Study Short-Form 12 and the EuroQol-5D, as well as an obesity-specific measure, the Impact of Weight on Quality of Life. Differences in HRQoL were compared among participants with and without metabolic syndrome. Multivariable linear regression was used to determine how HRQoL varied according to metabolic syndrome status, and whether factors including weight, depression and burden of comorbid disease modified this relationship. Results: Metabolic syndrome was not associated with HRQoL as assessed by any of the measures. In univariable analysis, depression, disease burden and employment status were significantly associated with worse HRQoL on all instruments. In multivariable models, only depression remained significantly associated with reduced HRQoL on all measures. Increasing obesity and diabetes status did not modify the relationship between metabolic syndrome and HRQoL. Conclusion: In contrast to previous studies, metabolic syndrome was not associated with impaired HRQoL as assessed by multiple measures. This suggests that metabolic syndrome in itself is not associated with decreased HRQoL, but other factors such as obesity, depression and greater disease burden may significantly influence the quality of life in this population. International Journal of Obesity (2011) 35, 1087-1094; doi:10.1038/ijo.2010.230; published online 2 November 2010