A new working paper published by the National Bureau of Economic Research (NBER) shows how much high-deductible health plans reduce spending:
We study consumer responsiveness to medical care prices, leveraging a natural experiment that occurred at a large self-insured firm which forced all of its employees to switch from an insurance plan that provided free health care to a non-linear, high deductible plan. The switch caused a spending reduction between 11.79%-13.80% of total firm-wide health spending ($100 million lower spending per year). We decompose this spending reduction into the components of (i) consumer price shopping (ii) quantity reductions (iii) quantity substitutions, finding that spending reductions are entirely due to outright reductions in quantity. We find no evidence of consumers learning to price shop after two years in high-deductible coverage. Consumers reduce quantities across the spectrum of health care services, including potentially valuable care (e.g. preventive services) and potentially wasteful care (e.g. imaging services).
(Z.C. Brot-Golberg, et al., What Does a Deductible Do? The Impact of Cost-Sharing on Health Care Prices, Quantities, and Spending Dynamics,” NBER WP No. 21632, October 2015.)