Costs of Coexisting Depression and Diabetes

A ccording to the Global Burden of Disease Study 2010 and the World Health Organization, diabetes and depression are leading causes of disability. In the United States, approximately 25.6 million adults have diabetes mellitus (11.3% of the population). The burden of diabetes is anticipated to grow, with estimates suggesting that the proportion of the population affected by diabetes and related costs will at least double in the next 25 years, yet the proportion of adults whose diabetes is controlled is decreasing over time and is particularly low among older adults and ethnic minorities. Depression is a risk factor for diabetes and risk of depression is increased by a factor of two in patients with diabetes. Depressive symptoms contribute to poor patient engagement, poor adherence to medication and dietary regimens, poor glycemic control, reduced quality of life, and increased health expenditures. The influence of depression on outcomes for diabetes includes both biological mechanisms such as increased inflammation, poor self-care, and decreased adherence to treatment regimens. For patients with diabetes, depression has been specifically linked to prognostic variables such as microvascular and macrovascular complications. Depression has been found to increase all-cause mortality even in the context of good glucose control. For diabetes, increasing attention has been given to the principle that day-to-day management should be in the hands of patients themselves. Self-care activities (e.g., checking one’s own finger-stick blood sugar), health behaviors (e.g., smoking, alcohol use, diet, physical activity), and patient choice (e.g., whether to start a new medication or undergo a procedure) all profoundly affect outcomes in diabetes and all are strongly influenced by depression. The biological, social, psychological, and behavioral links between depression and diabetes provide a strong incentive to examine the healthcare costs of depression in adults with diabetes. Moreover, national estimates of the healthcare costs of comorbid depression and diabetes are essential for providing decision makers with needed information to inform policy and practice changes. In this issue of JGIM, Egede et al. investigate the trends in healthcare costs over 8 years in patients aged 18 years and older with diabetes. Based on International Classification of Diseases, Clinical Modification (ICD-9-CM) codes to measure the presence or absence of a depression diagnosis and the two-item Patient Health Questionnaire (PHQ-2) to measure the presence or absence of depressive symptoms, patients with diabetes were classified as no depression, unrecognized depression, asymptomatic depression, or symptomatic depression. The authors report that patients with unrecognized and asymptomatic depression had healthcare expenditures that were $2000–$3000 higher compared to patients with no depression, and patients with symptomatic depression had healthcare expenditures that were $5000 higher compared to patients with no depression after adjustment for potentially influential covariates. The authors adjusted for sociodemographic factors, comorbidities, and time trend covariates. No depression was associated with the lowest total, inpatient, outpatient, prescription, office-based, and emergency room costs, and symptomatic depression was associated with the highest costs of all types. The authors found the higher medical expenditures associated with depression persisted over time. This study used data from the 2004–2011 Medical Expenditure Panel Survey (MEPS), a nationally representative estimate of healthcare expenditures maintained and cosponsored by the Agency for Healthcare Research and Quality (AHRQ). The MEPS data spanned 8 years and involved 15,548 adults with diabetes. The large ethnically diverse and nationally representative sample and the pooled data set over 8 years are significant strengths. Because of the focus on costs due to medical expenditures, other nonmedical costs related to caregiving, community services, short-term sick leave, and social services are not included and are an important area of future inquiry. The overall mean medical expenditures for patients with diabetes and no depression was $10,016 (95 % CI 9589– 10,442), with unrecognized depression was $15,155 (95 % CI 13,587–16,723), with asymptomatic depression was $16,134 (95 % CI 14,885–17,382) and with symptomatic depression was $20,105 (95 % CI 18,103–22,106). Pairwise comparison tests showed the mean expenditure between all groups were significantly different, except between asymptomatic and unrecognized depression. However, compared to unrecognized depression, the costs associated with asymptomatic depression were higher for prescriptions and office based visits, presumably as a result of treatment. The benefit of treatment is consistent with the lower overall mean medical expenditures Published online March 23, 2016