The Effect of Medicare Part D on Drug and Medical Spending.

Background: It is not known what effect the increased use of prescription drugs by enrollees in Medicare Part D has had on spending for other medical care. Methods: We compared spending for prescription drugs and other medical care 2 years before the implementation of Part D in January 2006 with such expenditures 2 years after the program's implementation in four groups of elderly beneficiaries: Medicare Advantage enrollees with stable, uncapped, employer-based drug coverage throughout the study period (no-cap group), those who had no previous drug coverage, and those who had previous limited benefits (with either a $150 or a $350 quarterly cap) before they were covered by Part D in 2006. Results: Between December 2005 and December 2007, as compared with the increase in the no-cap group, the increase in total monthly drug spending was $41 higher (95% confidence interval [CI], $33 to $50) (74%) among enrollees with no previous drug coverage, $27 higher (95% CI, $20 to $34) (27%) among those with a previous $150 quarterly cap, and $13 higher (95% CI, $8 to $18) (11%) among those with a previous $350 cap. The use of both lipid-lowering and antidiabetic medications rose in the groups with no or minimal previous drug coverage. As compared with expenditures in the no-cap group, monthly medical expenditures (excluding drugs) were $33 lower (95% CI, $29 to $37) in the group with no previous coverage and $46 lower (95% CI, $29 to $63) in the group with a previous $150 quarterly cap, whereas medical spending was $30 higher (95% CI, $25 to $36) in the group with a previous $350 cap. Conclusions: Enrollment in Medicare Part D was associated with increased spending on prescription drugs. Groups that had no or minimal drug coverage before the implementation of Part D had reductions in other medical spending that approximately offset the increased spending on drugs, but medical spending increased in the group that had more generous previous coverage. N Engl J Med 2009;361:52-61.