Impact of Comorbid Attention Deficit Disorder on the Direct Medical Costs of Treating Adults With Depression in Managed Care

Paul A. Fishman, Ph.D.; Paul E. Stang, Ph.D.; and Susan L. Hogue, Pharm.D., M.P.H.

Objective: To assess the impact of comorbid attention deficit disorder (ADD) on the direct medical costs of treating adults with depression in a mixed-model health maintenance organization.

Method: Annual mean and marginal health care costs were calculated for adults who were continuously enrolled at Group Health Cooperative during 2001 and who were diagnosed with depression, ADD, or both ADD and depression according to ICD-9-CM criteria during 2001.

Results: Of 249,874 adults continuously enrolled during 2001, 17,792 (7.1%) were diagnosed with depression, 1023 (0.4%) were diagnosed with ADD, and 454 (0.2%) were diagnosed with both depression and ADD. The mean total annual cost for an adult with a diagnosis of depression in 2001 exceeded that for the average adult enrolled in Group Health by 109% ($6029 vs. $2880). Of the $6029 mean total annual cost for treating an adult with a diagnosis of depression, $1872 (31%) was specifically attributable to depression. The presence of comorbid ADD resulted in ADD- and depression-attributed marginal costs approximately 29% higher than the costs specifically attributed to depression alone ($2418 vs. $1872). In fact, among patients with a diagnosis of ADD and depression, ADD- and depression-attributed costs approached the mean total cost of health care in the sample as a whole ($2880).

Conclusion: Depression is associated with high direct medical costs. The marginal costs of treating comorbid depression and ADD substantially exceed those of treating depression alone. These results underline the importance of considering the costs of comorbidities in estimating the economic burden of depression and developing cost-effective disease-management strategies.

(J Clin Psychiatry 2007;68:248-253)

Received Oct. 20, 2005; accepted June 26, 2006. From the Center for Health Studies, Group Health Cooperative, Seattle, Wash. (Dr. Fishman); Galt Associates, Blue Bell, and West Chester University College of Health Sciences, West Chester, Pa. (Dr. Stang); and Global Health Outcomes, GlaxoSmithKline, Research Triangle Park, N.C. (Dr. Hogue).

GlaxoSmithKline, Research Triangle Park, N.C., funded the research described in this study.

The authors acknowledge the assistance of Jane Saiers, Ph.D., in writing the manuscript. Dr. Saiers received compensation from GlaxoSmithKline for her work.

Dr. Fishman reports no other financial affiliations relevant to the subject of this article. Dr. Stang serves as a consultant to, has received grant/research support and honoraria from, and serves on the speakers or advisory boards for multiple pharmaceutical companies, including GlaxoSmithKline. Dr. Hogue is a full-time employee of GlaxoSmithKline.

Corresponding author and reprints: Paul A. Fishman, Ph.D., Center for Health Studies, Group Health Cooperative, 9750 3rd Ave. NE, Seattle, WA 98101 (e-mail: fishman.p@ghc.org).