Association Between Generalized Anxiety Disorder and Asthma Morbidity

Background: Generalized anxiety disorder (GAD) is common among people with asthma, but its association with asthma morbidity remains unexplored. This study examined cross-sectional associations between GAD and asthma control, quality of life, and self-efficacy. Methods: Seven hundred ninety-four adults with confirmed asthma were recruited from the outpatient clinic of a university hospital. Patients underwent a sociodemographic and medical history interview (to assess health service use and medications), followed by a brief psychiatric interview (Primary Care Evaluation of Mental Disorders) to assess GAD. Patients completed questionnaires assessing asthma control, quality of life, and asthma self-efficacy and underwent spirometry. General linear models and logistic regression were used to assess associations between GAD and asthma morbidity measures, adjusting for covariates. Results: GAD affected 4% of the sample. The analyses revealed significant associations between GAD and worse overall asthma control (β = 0.62, standard error SE = 0.18, p <.001), increased bronchodilator use (β = 10.60, SE = 2.64, p <.001), worse asthma quality of life (β = −0.91, SE = 0.23, p <.001), and worse asthma self-efficacy (β = −59.56, SE = 13.59, p <.001) after the adjustment for covariates. Separate sensitivity analyses including major depressive disorder and asthma self-efficacy as additional covariates rendered many of these associations nonsignificant. There were no associations between GAD and emergency visits or hospitalizations. Conclusions: GAD is associated with worse asthma morbidity independent of age, sex, smoking, and asthma severity; however, comorbid major depressive disorder and low asthma self-efficacy may account for many of these associations. Only breathlessness and the frequency of bronchodilator use were uniquely associated with GAD. Future research should examine whether treatment of GAD can affect asthma outcomes. ACQ = Asthma Control Questionnaire; ASES = Asthma Self-Efficacy Scale; ED = emergency department; FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity; GAD = generalized anxiety disorder; GLM = general linear model; ICC = intraclass correlation coefficient; ICS = inhaled corticosteroid; MDD = major depressive disorder; PD = panic disorder; PRIME-MD = Primary Care Evaluation of Mental Disorders.