Overlap of anxiety and depression in a managed care population: Prevalence and association with resource utilization.

OBJECTIVE: To characterize the diagnosis of anxiety and depression within a large managed care population and to measure the impact of having both of these conditions on treatment patterns, health care utilization, and cost. Further, to compare the impact of having both conditions with having neither or either condition alone.
METHOD: A retrospective, cross-sectional analysis of population-level anxiety-related and depression-related utilization over a 12-month study period was conducted. Data were from the PharMetrics Patient-Centric database, which is composed of medical and pharmaceutical claims for approximately 36 million patients from 61 health plans across the United States. Patients 18 years and older were included as cases in the analysis if they had a diagnosis of depression or anxiety during 2002. Four groups were identified based on the presence of anxiety and/or depression diagnosis: anxiety only, depression only, anxiety and depression, and controls. Controls were matched to the anxiety and depression cohort using a 4:1 ratio, based on patient age, gender, and similarity of health coverage. Cohorts were compared with respect to patient demographics, comorbid diagnoses, medication use, specialist care, utilization of health care services, and treatment costs, using both univariate and multivariate statistics.
RESULTS: Significant differences in comorbid diagnoses, medication use, health care utilization, and treatment costs existed between the study groups. Specifically, patients with both anxiety and depression tended to have more somatic complaints such as abdominal pain, malaise, or chest pain than patients with either condition alone or the control group. Antidepressant use was highest among the anxiety and depression cohort, while anxiolytic use was as prevalent in the anxiety and depression cohort as in the anxiety only cohort. Patients in the anxiety only, depression only, or anxiety plus depression groups had a higher number of anxiety- and/or depression-related visits as well as visits not related to depression or anxiety than the control group, with the anxiety and depression cohort incurring the highest utilization of medical services. Similarly, in terms of cost, the disease cohorts incurred significantly higher cost than their control counterparts, with the anxiety and depression cohort incurring higher cost than those with either condition alone, even after accounting for differences in patient characteristics.
CONCLUSIONS: Combination of anxiety and depression is fairly common in a managed care population as evidenced by diagnosis and treatment. The combination of both diagnoses appears to increase the complexity of these patients with respect to comorbid conditions as well as increases the economic cost to payers.