OBJECTIVES: Spending on prescribed medication may be different between insured and uninsured consumers. This study aims to compare prescribed medication spending controlling for medical insurance coverage for US residents from 1997 to 2015.

METHODS: Data for this study were obtained from the Medical Expenditure Panel Survey (MEPS). Persons were classifed into one of three medical insurance (hospital and physician) coverage groups: private; public; and uninsured. Sources of payment were categorized into private, public, self/family and other. Regression models were used to compare medical insurance status with respect to drug expenditures over time accounting for the complex sampling methods used by MEPS.

RESULTS: The proportion of population with private, public and no medical insurance ranged from 59.9% to 47.9%, 34.6% to 48.5% and 5.5%-3.6% from 1997 to 2015, respectively. Compared to private and public insured groups, the cost for prescribed medicines of the uninsured increased at a lower rate from $31.83-$54.96 versus $40.12-$75.58 and $36.00-$70.96 for private and publically insured, respectively (p < 0.01). For privately insured, publically insured, and uninsured, out-of-pocket costs decreased from 43.9%-15.5%, 41.5%-8.0%, and 90.2%-32.9%, respectively over time. Also, for privately insured, publically insured, and uninsured, payments from public sources increased from 3.8%-23.4%, 52.9%-87.3%, and 2.5%-26.7%. The amount of presription costs from private sources increased from 50.0%-56.9%, 1.0%-2.8%, and 2.7%-35.9% for private, public and medically uninsured, respectively. Regression models also indicated that growth of private payment in private and public insurance coverage group were significantly slower than uninsured group (both p <0.01). There was no significant difference between uninsured and private insurance groups in terms of public expenditures for prescription medications over time (p =0.76).

CONCLUSIONS: For medically uninsured individuals, out-of-pocket costs for prescription medications significantly declined over time. Additionally, over time the proportion of medication costs paid by public sources increased for all three groups.