Systematic review of clinical trials examining the effects of religion on health.

Using MEDLINE, (limited to the English language and the reference lists of the randomized controlled trials (RCTs), we assessed the impact of religion on health outcomes via systematic, critical review of the medical literature. All RCTs published from 1966 to 1999 and all non-RCTs published from 1996 to 1999 that assessed a relationship between religion and measurable health outcome were examined. We excluded studies dealing with non-religious spirituality, ethical issues, coping, well-being, or life satisfaction. We used the Canadian Medical Association Journal's guidelines for systematic review of the medical literature to evaluate each manuscript. Nine RCTs and 25 non-RCTs met these inclusion/exclusion criteria. Randomized controlled trials showed that intercessory prayer may improvehealth outcomes in patients admitted to a coronary care unit but showed no effect on alcohol abuse. Islamic-based psychotherapy speeds recovery from anxiety and depression in Muslims. Non-RCTs indicate that religious activities appear to benefit blood pressure, immune function, depression, and mortality.