Abstract
Background
The co-occurrence of depression and diabetes is an emerging global challenge but any association is influenced by variations in prevalence, study design and measure used. We compared depression prevalence in older adults with and without diabetes across three health systems using a validated measure to examine the causal association between diabetes and depression.
Methods
We used data of adults aged over 49 years, from three nationally representative ageing datasets; The Irish Longitudinal Study on Ageing (TILDA), the English Longitudinal Study on Ageing (ELSA) and the Health and Retirement Study (HRS). Data were collected during 2009–2011 (TILDA), and 2010 (ELSA, HRS). The 8-item CESD scale categorised depression using recommended cut-off scores of < 3 for ELSA and HRS and < 8 for TILDA. Self-reported individual, environmental, behavioural risk, and health system exposure variables were selected a-priori using literature and a directed acyclic graph. Prevalence was presented as a percentage with corresponding 95% confidence intervals. Binomial logistic regression examined the odds of depression by diabetes status. Data were analysed in Stata v15 using the ‘svy’ function.
Results
Diabetes prevalence (Ireland;8%[(95%CI:7.5–8.6), England;11%(95%CI:10.6–12.0) and USA;19%[(95%CI:18.8-20.1);p<0.001]) and depression prevalence (Ireland;10%(95%CI:9.0–10.6), England;16%(95%CI:15.3-16.9), USA;14%[(95%CI:13.5-14.7);p<0.001] varied across countries. Depression was consistently higher among people with versus without diabetes (Ireland;14%(95%CI:10.9-16.6)vs.9%(95%CI:8.7–10.3),p=0.001], England;25%(95%CI:21.7-27.7)vs.15%[(95%CI:14.2-15.9),p≤0.001] and USA;19%(95%CI:16.9-20.0)vs.13%[(95%CI:12.4-13.8);p≤0.001]. The odds of depression were significantly higher in people with versus without diabetes (Ireland;OR=1.5(95%CI:1.2-1.9);p=0.001, England;OR=1.8(95%CI:1.5–2.2);p<0.000, USA;OR=1.5(95%1.3-1.7);p<0.000), but only remained significant in the English sample after adjustment; (Ireland;OR=1.2(0.8-1.6);p=0.356, England;OR=1.3(1.0–1.6);p=0.045, USA;OR=1.0(0.9-1.1);p=0.898).
Conclusion
Among older adults in different health systems, depression was consistently higher among people with versus without diabetes. The findings support incorporation of holistic approaches to diabetes management across health systems.