Obesity and symptoms of depression contribute independently to the poor asthma control of obesity

Obesity is a major risk factor for poorly controlled asthma, but the reasons for poor asthma control in this patient population are unclear. Symptoms of depression have been associated with poor asthma control, and increase with higher body mass index (BMI). The purpose of this study was to assess whether depressive symptoms underlie poor asthma control in obesity. Methods: We determined the relationship between BMI, psychological morbidity and asthma control at baseline in a well-characterized patient population participating in a clinical trial conducted by the American Lung Association-Asthma Clinical Research Centers. Results: Obese asthmatic participants had increased symptoms of depression (Center for Epidemiologic Studies Depression Scale score in lean 10.1 +/- 8.1, overweight 10.0 +/- 8.1, obese 12.4 +/- 9.9; p = 0.03), worse asthma control (Juniper Asthma Control Questionnaire score in lean 1.43 +/- 0.68, overweight 1.52 +/- 0.71, obese 1.76 +/- 0.75; p < 0.0001), and worse asthma quality of life (scores in lean 5.21 +/- 1.08, overweight 5.08 +/- 1.05, obese 4.64 +/- 1.09; p < 0.0001). Asthmatics with obesity and those with symptoms of depression both had a higher risk of having poorly controlled asthma (adjusted odds ratio of 1.83 CI 1.23-3.52 for obesity, and 2.08 CI 1.23-3.52 for depression), but there was no interaction between the two. Conclusion: Obesity and symptoms, of depression are independently associated with poor asthma control. As depression is increased in obese asthmatics it may be an important co-morbidity contributing to poor asthma control in this population, but factors other than depression also contribute to poor asthma control in obesity. (C) 2014 Elsevier Ltd. All rights reserved.