The effect of cost sharing on the use of chiropractic services

Chiropractic care is increasing in the United States, and there are few data about the effect of cost sharing on the use of chiropractic services. This study calculates the effect of cost sharing on chiropractic use.

The authors analyzed data from the RAND Health Insurance Experiment, a randomized controlled trial of the effect of cost sharing on the use of health services. Families in six US sites were randomized to receive fee-for-service care that was free or required one of several levels of cost sharing, or to receive care from a health maintenance organization (HMO). Enrollees were followed for 3 or 5 years. All fee-for-service plans covered chiropractic services. Persons assigned to the HMO experimental group received free fee-for-service chiropractic care; persons in the HMO control group had 95% cost sharing for chiropractic services. The authors calculated the mean annual chiropractic expense per person in each of the fee-for-service plans, and also predicted their chiropractic expenditures using a two-equation model. Chiropractic use among persons receiving HMO and fee-for-service care were compared.

Chiropractic care is very sensitive to price, with any level of coinsurance of 25% or greater decreasing chiropractic expenditures by approximately half. Access to free chiropractic care among HMO enrollees increased chiropractic use ninefold, whereas access to free medical care decreased fee-for-service chiropractic care by 80%.

Chiropractic care is more sensitive to price than general medical care, outpatient medical care, or dental care, or and nearly as sensitive as outpatient mental health care. A substantial cross-price effect with medical care may exist.