Maybe it's providence or God's way of saying thank you, and maybe it's the relaxed ambience at houses of prayer, but mosques, churches, synagogues and shrines apparently keep the angel of death away. At least those are the findings of a study published recently by researchers at Yeshiva University and its medical school, the Albert Einstein College of Medicine. In one of the most comprehensive studies ever of the connection between religious practice and health, researchers found that regular attendance by post-menopausal women at religious services reduces the risk of death by approximately 20 percent. And the researchers don't know why. "There is something here that we don't quite understand," Dr. Eliezer Schnall, an assistant professor of clinical psychology at Yeshiva College and lead author of the study, told The Jerusalem Post on Sunday. "This was not just a correlational study. Rather, we conducted a prospective study that adjusted for different confounders such as prior health, socioeconomic level and age," he said. Schnall, who spoke to the Post by phone from New York, said that even after researchers adjusted for factors such as the enhanced social support enjoyed by those who attend houses of worship or the lower level of smoking and alcohol consumption found among the religiously observant, or the fact that those who managed to get out of the house to attend services were healthier, there was still a strong connection between attendance at religious services and lower mortality. "It is always possible that some unknown or unmeasured factors confounded these results," he said. "But we did not find any." The research was conducted by Schnall and co-authored by Sylvia Wassertheil-Smoller, a professor of epidemiology and population health at Einstein, as an ancillary study of the Women's Health Initiative (WHI). The WHI is a long-term study aimed at addressing women's health issues and funded by the US National Institutes of Health. Some 92,395 post-menstrual women - Christians, Muslims, Buddhists, Sikhs, Jews and women of other faiths - ages 50 to 70 were recruited on a voluntary basis from all over the US. The women were followed by researchers on average for 7.7 years, some for more time, some for less, depending on when they were interviewed and whether they died during the study. The women answered myriad questions about their health and their religiosity. Regarding attendance rates at a place of worship, there were four possible answers: never, less than once a week, once a week and more than once a week. Those attending religious services at least once per week showed a 20% mortality risk reduction mark compared with those not attending services at all. These findings corroborate prior studies that have shown up to a 25% reduction in such risk. Schnall said that what was new about the Yeshiva University study was the sheer amount of data. "Unlike previous studies that found a connection between religiosity and mortality rates, the WHI provided us a vast amount of information that enables us to better adjust for numerous confounding factors. "Our study is particularly newsworthy because it was very large, it was conducted across the country and it included different ethnic and geographical areas," he said. Full details of the findings have been published in Psychology and Health, the journal of the European Health Psychology Society. Although investigators concluded that regular attendance at places of worship is associated with a reduction in death rates among the study population, the physical relationships leading to that effect are not yet understood and require further investigation. "The next step is to figure out how the effect of religiosity is translated into biological mechanisms that affect rates of survival," said Wassertheil-Smoller. "However, we do not infer causation even from a prospective study, as that can only be done through a clinical trial." She added, "There may be confounding factors that we can't determine, such as a selection bias, which would lead people who are at reduced risk for an impending event to also be the ones who attend services." In addition to attendance at places of worship, the study also checked the impact of religious affiliation and self-reported religiosity on mortality. But after adjusting for other factors such as the social benefits of religious affiliation, the impact on mortality was inconsequential.