The association between asthma and depression: an analysis of 244,727 women and men from 56 countries

Background: There is consistent evidence for the co-occurrence of asthma and depression in Western populations, but little is known about the association in non-western populations. We therefore investigated the relationship between asthma and depression based on data from a large multi-national survey. Methods: The 2002 World Health Survey was carried out on five continents and in 70 countries. Asthma was measured by self-reports of the physician diagnosis. Multiple questions assessed the experience of depressive symptoms during the previous year. These questions were combined with questions on the symptom duration and stability to define presence of a major depressive episode (MDE). Logistic regression was employed to estimate odds ratios (ORs) and 95% confidence intervals (CIs) using the generalized link function and country-specific sample weights. Estimates were adjusted for age, sex, and education. The analyses were restricted to the 56 countries with information on sampling weights and complete information on asthma, MDE and the confounders. The total sample comprised 244,727 individuals ranging from n=700 for Luxembourg to n=38,745 for Mexico. ORs were calculated for each country, for continents and for the overall sample. Results: Within each continent, positive and statistically significant associations between asthma and MDE could be observed for many countries. We found positive associations between asthma and MDE for all five continents, that is, Australia (OR=1.66; 95% CI=1.14–2.41), Europe (OR=1.74; 95% CI=1.32–2.30), Africa (OR=1.77; 95% CI=1.38–2.26), the Americas (only Latin American countries were included in the sample) (OR=2.86; 95% CI=2.28–3.60) and Asia (OR=2.53; 95% CI=2.11–3.04). The OR for the entire sample was 2.45 (95% CI=2.18–2.75). Conclusions: This study suggests that the association between asthma and depression is not limited to Western populations, but is also observed in many non-western populations.