The association of asthma and wheezing with major depressive episodes: an analysis of 245 727 women and men from 57 countries.

BACKGROUND: Epidemiological studies have shown that asthma is positively associated with depression. Most of this evidence stems from individual studies conducted in Western populations (e.g. Europe, North America and Australia). It is still unclear whether such findings generalize to non-Western countries. To address this question, the present study investigated the association of asthma and wheezing with depression in a large multi-national sample.
METHODS: We used data from the 2002 World Health Survey. Participants reported physician-diagnosed asthma and attacks of wheezing within the past 12 months. Questions on depressive symptoms, their duration and persistence were used to define presence of a major depressive episode (MDE) within the past 12 months. ORs and 95% CIs were estimated by logistic regression for the entire sample, by continent (Australia, Europe, South America, Asia and Africa) and by country. Complete information was available for 57 countries.
RESULTS: Both asthma and wheezing were associated with MDE in the entire sample (OR=2.37, 95% CI=2.10-2.66 and OR=3.06, 95% CI=2.75-3.40, respectively). Similar associations were found for all continents with generally stronger ORs in South America, Asia and Africa for both asthma (ORs ≥ 1.8) and wheezing (ORs  ≥ 2.8). On the country level, wheezing showed a consistent pattern of association with MDE. Similar patterns were found for asthma.
CONCLUSIONS: Despite a range of country differences that could affect the association of asthma with depression, such as access to health care, the results of this study indicate that the co-occurrence of asthma and depression is a universal phenomenon.