Depressive Symptoms and All-Cause Mortality in Older American Indians with Type 2 Diabetes Mellitus

OBJECTIVES American Indians experience disproportionately high rates of poor mental health and type 2 diabetes mellitus (T2DM). We examined the association between depressive symptoms and all-cause mortality in older American Indians with T2DM. DESIGN We used the Native Elder Care Study survey data from community-dwelling American Indians aged 55 years or older, linked to data extracted from participants' electronic health records. We focused on those who had an International Classification of Diseases-Ninth Revision diagnosis of T2DM in their electronic health records. SETTING The study was conducted with a federally-recognized tribe with approximately 16,000 enrolled members, most of whom reside on or near tribally-owned lands that span several rural counties. PARTICIPANTS Participants were among the Native Elder Care Study participants with a final analytic sample of 222. MEASUREMENTS We measured depressive symptoms with the Centers for Epidemiologic Studies-Depression (CES-D) scale. We used Cox proportional hazard models to examine the association between depressive symptoms and all-cause mortality in the final analytic sample of 222 subjects. RESULTS Survival curves revealed that individuals in the third and fourth CES-D scale categories had higher mortality than those in the first and second categories. Mortality risk was significantly higher for participants with CES-D scale scores in the third highest compared with the lowest category (hazard ratio = 2.07; 95% confidence interval = 1.07-4.04), after adjustment for demographic characteristics, health behaviors, obesity, and prevalent T2DM complications. Analyses with the CES-D scale as a continuous variable also showed a positive association with mortality. CONCLUSION The impact of mental health on older American Indians with T2DM is often overlooked, yet it is vital to clinical and public health practice. Our findings underscore the importance of addressing the mental health needs of this population, particularly because depression in older patients is often undetected or inadequately treated.