Abstract

STUDY OBJECTIVE: Relative risks are frequently assumed to be stable across populations but this may not apply in psychiatric epidemiology where sociocultural context may modify them. Such ecological effect modification will give curved associations between aggregated risk factor and outcome. This was examined in connection with the ecological association between suicide rates and an aggregate index of religiosity. DESIGN: Ecological study of associations between suicide rates and an index of religiosity, adjusted for socioeconomic variation. The effect of stratification of the study sample according to levels of religiosity, was examined. SETTING: 26 European and American countries. SUBJECTS: Interview data from 37,688 people aggregated by country. OUTCOME MEASURES: Age and sex specific (1986-1990) suicide rates. MAIN RESULT: Adjusted for socioeconomic variation, negative associations of male suicide rates with religiosity were apparent in the 13 least religious countries only (test for interaction F (1, 25) = 5.6; p = 0.026). Associations between religiosity and female suicide rates did not vary across countries. CONCLUSION: The bent ecological association was apparent only after adjustment for socioeconomic variation suggesting that, rather than confounding, ecological modification of individual level links between religion and male (but not female) suicide risk is the responsible mechanism. This concurs with micro-level findings suggesting that suicide acceptance depends not only on personal but also on contextual levels of religious belief, and that men are more sensitive to this phenomenon than women. In psychiatric epidemiology, relative risks vary with the exposure's prevalence. This has important implications for research and prevention.