Workplace wellness programs cover over 50 million workers and are intended to
reduce medical spending, increase productivity, and improve well-being. Yet, limited
evidence exists to support these claims. We designed and implemented a comprehensive
workplace wellness program for a large employer with over 12,000 employees, and randomly
assigned program eligibility and financial incentives at the individual level. Over
56 percent of eligible (treatment group) employees participated in the program. We find
strong patterns of selection: during the year prior to the intervention, program participants
had lower medical expenditures and healthier behaviors than non-participants.
However, we do not find significant causal effects of treatment on total medical expenditures,
health behaviors, employee productivity, or self-reported health status in the first
year. Our 95% confidence intervals rule out 83 percent of previous estimates on medical
spending and absenteeism. Our selection results suggest these programs may act as a
screening mechanism: even in the absence of any direct savings, differential recruitment
or retention of lower-cost participants could result in net savings for employers.