Background and objective: In patients with coronary artery disease (CAD), obesity is paradoxically associated with better survival (the 'obesity paradox'). Our objective was to determine whether this counterintuitive relationship extends to health-related quality of life (HRQOL) outcomes.
Design: Cross-sectional observational study.
Subjects: All adults undergoing coronary angiography residing in Alberta, Canada between January 2003 and March 2006 in the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) registry.
Methods: Patients completed self-reported questionnaires 1 year after their index cardiac catheterization, including the Seattle Angina Questionnaire (SAQ) and the EuroQol 5D (EQ-5D Index). Patients were grouped into six body mass index (BMI) categories (underweight, normal, overweight, mild obesity, moderate obesity and severe obesity). An analysis of covariance was used to create risk-adjusted scores.
Results: A total of 5362 patients were included in the analysis. Obese patients were younger than normal and overweight participants, and had a higher prevalence of depression and cardiovascular risk factors. In the adjusted models, SAQ physical function scores and the EQ Index (representing overall QOL) were significantly reduced in patients with mild, moderate and severe obesity compared with patients with a normal BMI. Patients with severe obesity had both statistically and clinically significant reductions in HRQOL scores. Depressive symptoms accounted for a large proportion in variability of all HRQOL scores.
Conclusions: BMI is inversely associated with physical function and overall HRQOL in CAD patients, especially in patients with severe obesity. High body weight is a modifiable risk factor; however, given the apparent obesity paradox in patients with CAD, it is critical that future studies be conducted to fully clarify the relationships between HRQOL and body composition (body fat and lean mass), nutritional state and survival outcomes.