Effects of Medical Comorbidity on Anxiety Treatment Outcomes in Primary Care

Objective To evaluate the effects of medical comorbidity on anxiety treatment outcomes. Methods Data were analyzed from 1004 primary care patients enrolled in a trial of a collaborative care intervention for anxiety. Linear-mixed models accounting for baseline characteristics were used to evaluate the effects of overall medical comorbidity (two or more chronic medical conditions [CMCs] versus fewer than two CMCs) and specific CMCs (migraine, asthma, and gastrointestinal disease) on anxiety treatment outcomes at 6, 12, and 18 months. Results At baseline, patients with two or more CMCs (n = 582; 58.0%) reported more severe anxiety symptoms (10.5 [95% confidence interval {CI} = 10.1–10.9] versus 9.5 [95% CI = 9.0–10.0], p = .003) and anxiety-related disability (17.6 [95% CI = 17.0–18.2] versus 16.0 [95% CI = 15.3–16.7], p = .001). However, their clinical improvement was comparable to that of patients with one or zero CMCs (predicted change in anxiety symptoms = −3.9 versus −4.1 at 6 months, −4.6 versus −4.4 at 12 months, −4.9 versus −5.0 at 18 months; predicted change in anxiety-related disability = −6.4 versus −6.9 at 6 months, −6.9 versus −7.3 at 12 months, −7.3 versus −7.5 at 18 months). The only specific CMC with a detrimental effect was migraine, which was associated with less improvement in anxiety symptoms at 18 months (predicted change = −4.1 versus −5.3). Conclusions Effectiveness of the anxiety intervention was not significantly affected by the presence of multiple CMCs; however, patients with migraine displayed less improvement at long-term follow-up. Conclusions Trial Registration: ClinicalTrials.com Identifier: NCT00347269