Medication Costs and Adherence of Treatment Before and After the Affordable Care Act: 1999-2015.

To examine national changes in rates of cost-related prescription nonadherence (CRN) by age group, we used data from the 1999-2015 Sample Adult and Sample Child National Health Interview Surveys (n = 768 781). In a logistic regression analysis of 2015 data, we identified subgroups at risk for cost-related nonadherence. The proportion of all Americans who did not fill a prescription in the previous 12 months because they could not afford it grew from 1999 to 2009, peaking at 8.3% at the height of the Great Recession and dropping to 5.2% by 2015. CRN among seniors, however, peaked in 2004 at 5.4% and dropped to 3.6% after implementation of Medicare Part D in 2006. CRN is responsive to improved access related to implementation of Medicare Part D and the Affordable Care Act.