Association Between Cognitive Function and Health Care Costs 3 Months and 6 Months After Initiating Antidepressant Medication for Depressive Disorders.

Abstract

Major depressive disorder is one of the most common and disabling mental health disorders and is associated with substantial costs in terms of direct health care utilization and workplace productivity. Cognitive dysfunction, which alone substantially increases health care costs, is commonly associated with major depressive disorder. However, the health care costs of cognitive dysfunction in the context of depressive disorder are unknown. Recovery from mood symptoms is not always associated with resolution of cognitive dysfunction. Thus, cognitive dysfunction may contribute to health care burden even with successful antidepressant therapy. To compare health care utilization and costs for patients with a depressive disorder with and without cognitive dysfunction, at 3 and 6 months after initiation of antidepressant medication. This was an observational study, combining a cross-sectional patient survey, administered during a telephone interview, with health care claims data from a large, geographically diverse U.S. health plan. Included patients had at least 1 pharmacy claim for an antidepressant medication between August 1 and September 30, 2012, and no claim for any antidepressant during the 6 months prior to the index date. In addition to other criteria assessed in the claims data, patients confirmed a diagnosis of depression or major depressive disorder and the absence of any exclusionary neurological diagnoses possibly associated with cognitive impairment. Eligible patients were administered validated cognitive function assessments of verbal episodic memory (Hopkins Verbal Learning Test-Revised, Delayed and Total); attention (Digit Span Forward Maximum Sequence Length); working memory (Digit Span Backward Maximum Sequence Length); and executive function (D-KEFS-Letter Fluency Test). Based on comparison of scores with normative data, patients were assigned to cognitive dysfunction or cognitive normal cohorts. All-cause (all diagnoses) and depressive disorder-related health care utilization and costs (all from a payer perspective) were assessed 6 months prior (baseline) to antidepressant initiation and 3 months and 6 months after (follow-up) initiation of antidepressant medication. Health care utilization and costs included ambulatory (office and hospital outpatient), emergency room, inpatient hospital, pharmacy, other medical (e.g., laboratory and diagnostics), and total (all categories combined). All-cause and depressive disorder-related total costs during the 3- and 6-month follow-up periods were modeled with generalized linear modeling with gamma distribution and log link, while adjusting for potential confounders (age, race, gender, education, employment, and comorbidities). Of the 13,537 patients who were mailed an invitation, 824 (6%) were eligible and agreed to participate. Of these, 563 patients provided informed consent, completed the interview, maintained eligibility, and were included in the 3-month calculations. Among these, 255 (45%) were classified as having cognitive dysfunction. Mean patient age was 41.3 (± 12.5) years; 80% were female. Most patients were white and employed. More patients in the cognitive normal cohort were white (P  less than  0.001) and employed full time (P = 0.029), had higher education attainment (P  less than    0.001), and had fewer comorbidities (P = 0.007) than those in the cognitive dysfunction cohort. Over the first 3 months, patients with cognitive dysfunction had higher adjusted all-cause costs ($3,309 vs. $2,157, P = 0.002) and higher adjusted depressive disorder-related costs ($718 vs. $406, P  less than  0.001) than patients without cognitive dysfunction. At 6 months, data from 4 patients were removed from the analysis because of exclusionary diagnoses. Over 6 months, patients with cognitive dysfunction had higher adjusted all-cause costs ($4,793) than patients without cognitive dysfunction ($3,683, P = 0.034). Over 6 months, depressive disorder-related costs did not significantly differ between patients with ($771) and without cognitive dysfunction ($594, P = 0.071). The main drivers of all-cause costs were office visits, outpatient hospital visits, and inpatient costs, and the main driver of depressive disorder-related costs was inpatient costs. Cognitive dysfunction was associated with higher adjusted all-cause and depressive disorder-related costs 3 months after initiation of an antidepressant medication. This difference persisted for all-cause costs through 6 months. Identification and treatment of cognitive dysfunction in patients with depressive disorder might reduce health care costs.