Spiritual Complementary and Alternative Medicine Practices, Health-Related Behaviors, and Mortality Among US Adults: A National Health Interview Survey-Based Cohort Study

Background Relatively few studies have examined population-level impacts of spiritual practices on health. The National Health Interview Survey (NHIS) asks adults about spiritual practices for their own health in a complementary and alternative medicine (CAM) module roughly every five years. The Centers for Disease Control and Prevention (CDC) linked 1986 to 2018 surveys to the National Death Index. Objective Study objectives are to 1) compare spiritual practices as asked within CAM modules to mortality by the end of 2019, adjusting for respondent characteristics; 2) identify how health behaviors changed over time, particularly with regards to spiritual practices; and 3) explore significant interaction effects of spiritual practices in relation to mortality. Methods As three different spiritual practices were asked across 1999, 2002, 2007, 2012, and 2017, we ran survey-adjusted bivariate Chi-square tests of health behaviors by spiritual practice (yes/no) by grouping of years. Guided by the Andersen Behavioral Model, we included many socio-demographics, health status, and health behavior variables in a fully saturated, survey-adjusted Cox proportional hazards regression with mortality (yes/no) as the dependent variable and age at survey as the time variable. Due to top-coding at 85 years, analysis was limited to 18-84 years of age. A follow-up regression included interaction terms of spiritual practices with respondent characteristics. We also ran a sensitivity analysis to assess potential bias due to missing data. Results Among adults (n=137,291), 11.51% had died by the end of 2019. In 1999, an estimated 27.0 million adults (13.7% of adults that year) reported using spiritual healing/prayer for their own health. In 2002 and 2007, an estimated 92.6 million adults annually (43.9% of adults) reported praying for your own health. In 2012 and 2017, an estimated 16.2 million (6.9% of adults) reported using spiritual meditation for own health. Diabetes and currently smoking were most strongly associated with mortality, hazard ratios of 2.35 and 2.10, respectively, p<0.0001. Praying for own health was associated with higher mortality risk, HR: 1.07 (95% confidence interval: 1.01-1.13, p=0.012), while the other practices were not significant. In the interaction analysis, prayer by itself was no longer significant, but there was a significant interaction between prayer and binge drinking (HR=1.21, 95% CI: 1.02-1.30, p=0.026). All three spiritual practices for own health were associated with not currently smoking and receiving flu vaccination in past year. Most spiritual practices, except prayer, were associated with having a dentist visit in prior year and being more likely to do any moderate exercise/vigorous exercise/strength training in past week. Most spiritual practices, except spiritual meditation, were associated with not binge drinking in past year. For example, any binge drinking was reported by 15.0% (95% CI: 14.4-15.7) of those with prayer for health compared to 24.4% (23.6-25.2) of others in 2002 and 2007. There were secular changes, with smoking being less prevalent in 2012 and 2017 compared to prior years while exercise was more common. Conclusion Millions of adults used spiritual practices for health and generally also had positive health-related behaviors. Spiritual practices were associated with mortality largely through health behaviors. Differences between spiritual practices and binge drinking deserve further study.