Population-based Estimates of Incidence and Prevalence of Depression in People with Diabetes
Diabetes is a chronic medical condition that is complicated by depression. Feelings of hopelessness and decreased motivation due to depression result in poor management of chronic disease and increased risk of development of complications in patients with diabetes. The prevalence of depression in patients with diabetes has been reported in the literature as approximately twice the rate compared to people without diabetes, with odds ratios ranging from 1.58 to 2.0. Only a few small studies have reported the incidence of diabetes in people with depression whereas there is no available literature on the incidence of depression in people with diabetes. Therefore, the temporality of the relationship between depression and diabetes (i.e., which came first) is unclear, as prevalence measures do not allow for the determination of causality.
The main objectives of this study are to derive population-based estimates of the incidence of depression among people with diabetes and assess the temporal relationship between depression and diabetes. We will conduct a retrospective cohort study using the administrative databases of Saskatchewan Health to address these study questions. Individuals eligible for inclusion in this study will be adult residents of Saskatchewan during January 1, 1994 and December 31, 2001. A cohort of individuals with diabetes will be compared to a control cohort identified from the non-diabetes population during the same period. Our primary outcome will be ongoing depression. All outcomes will be based on records of drug use or diagnostic codes for depression in the administrative databases. We will first assess the prevalence of previous depression at the time of identification of diabetes and estimate the odds of previous depression. Among those people without a previous history of depression, we will then estimate the relative risk for the development of new onset chronic depressive episode in individuals with diabetes compared to those without diabetes.
Jeff Johnson, Sumit Majumdar, Stephen Newman, Lauren Brown
Institute of Health Economics
Canadian Institutes of Health Research
Brown LC, Majumdar SR, Newman SC, Johnson JA. History of depression increases risk of type 2 diabetes in younger adults. Diabetes Care 2005;28:1063-1067.
Brown LC, Majumdar SR, Newman SC, Johnson JA. Type 2 diabetes does not increase risk of depression. Canadian Medical Association Journal 2006;175:42-46.
Brown LC, Majumdar SR, Johnson JA. Type of antidepressant therapy and risk of type 2 diabetes in people with depression. Diabetes Research and Clinical Practice 2007 (forthcoming).