Depression and chronic diseases: Co-occurrence and communality of risk factors.

Background: The aim of current study is to assess the cross-sectional association of chronic non-communicable diseases (diabetes mellitus, arthritis, asthma, chronic lung disease, angina, and stroke) with both diagnosed and undiagnosed depression in the World Health Organization (WHO) Study on global AGEing and adult health (SAGE) Wave 1, a study of adults in six low- and middle-income countries.

Methods: A total of 41,810 participants, aged ≥ 18 years, were included. Depression status was assessed by standard methods derived from the World Mental Health Survey (WHH-CIDI). Undiagnosed depression was defined as a depressed person who did not report history of diagnosis/treatment for depression. Associations between depression/undiagnosed depression and chronic diseases, adjusting for country of residence, demographics and chronic diseases risk factors were assessed.

Results: Depression was detected in 2508 (6.0%) cases, from whom 2098 (87%) were undiagnosed. Diabetes (Odds ratio:1.47[95%CI:1.24,1.75]), arthritis (2.14[1.82,2.52]), asthma (3.36[2.73,4.14]), chronic lung disease (3.74[3.10,4.51]), angina (3.20[2.66,3.85]), and stroke (3.14[2.55,3.86]) were associated with depression (p-values < 0.001). Being older, female, underweight, and having lower education, and lower income were positively associated with depression. The estimated odds ratios were similar for undiagnosed depression.

Limitations: Cross-sectional design of study prevent us to determine whether depression followed exposures in time. About 12% of the participant did not have data for depression status and were excluded from the study.

Conclusions: Most depression cases were undiagnosed. Depression/undiagnosed depression were strongly associated with chronic diseases; stronger than what has been reported in developed countries.