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. Trial Registration ClinicalTrials.com Identifier: NCT00347269.
Keywords: anxiety; asthma; medical illness; migraine; primary care; randomized controlled trial.