Medicare Drug Coverage and the Impact on Overall Health Care Spending

By Clive Riddle, July 8, 2009

An important paper reporting on results of an NIH funded study : “The Effect of Medicare Part D on Drug and Medical Spending”was posted online last week with the New England Journal of Medicine: [Volume 361:52-61 July 2, 2009 Number 1] and authored by Yuting Zhang, Ph.D., Julie M. Donohue, Ph.D., Judith R. Lave, Ph.D., Gerald O'Donnell, M.S., and Joseph P. Newhouse, Ph.D..

The pharma industry for decades has been a proponent that appropriate prescription coverage can have a positive impact on overall health care costs. Certainly Medicare policy advocates argued the point in the debate leading up to establishment of Medicare Part D prescription coverage earlier this decade. Now that time has passed, the opportunity has arisen to examine the actual data to address this issue.

The study examined over 35,000 Medicare members from Pennsylvania’s Highmark Blue Cross Blue Shield from 2004 through 2007. The study included a control group with employer based retiree drug coverage that did not change after Part D took effect, and had $10 to $20 copayments with no spending limits or coverage gaps. Three groups were also examined that had no or limited drug coverage before Part D, and then enrolled as in Part D plan as of January 2006. One group had no previous drug coverage, and the other two had previous drug benefits with quarterly spending limit caps.

The study found that the cost of introduction of Part D benefits for those with no or very limited prior coverage was approximately offset by savings in overall health care costs, but overall health care spending did increase for those with more generous prior coverage.

In comparison to the control group, after introduction of Part D, the average total monthly drug spending was $41 higher (74% increase) for enrollees with no previous drug coverage, $27 (27% increase) higher among those with a previous $150 quarterly cap, and $13 higher among those with a previous $350 quarterly cap (11% increase.) Furthermore, overall monthly medical expenditures (excluding drugs) were $33 lower in the group with no previous coverage, $46 lower in the group with a previous $150 quarterly cap, but $30 higher in the group with a previous $350 quarterly cap.

The study concluded that “The offsetting reduction in medical spending in the two groups with the most limited previous benefits was probably due to improved medication adherence among enrollees with chronic conditions.” The study also addressed the overall health care cost increase for the group with more generous prior coverage: “Why did medical spending rise in the group with a previous $350 quarterly cap (the most generous previous coverage among the three intervention groups), as compared with the no-cap group? The additional use of prescription drugs in all three groups probably included both overuse of some drugs and underuse of others, but the proportion of the increase that was overuse may have been highest in the group with the most generous previous coverage. Our finding that the use of oral antidiabetic drugs did not change significantly in this group is consistent with this hypothesis.”

The References section at the end of the report is well worth browsing, as links to various prior studies are provided. Beyond the References provided in the report, I found two other studies that proved to be of particular interest while researching this topic:

The AARP Public Policy Institute published “How Prescription Drug Use Affects Health Care Utilization and Spending by Older Americans: A Review of the Literature” by Cindy Parks Thomas, Ph.D., Brandeis University, Schneider Institute for Health Policy, in April 2008. Key conclusions from this 57 page report include: (1) “Prescription drug coverage can produce cost offsets from reductions in non-drug services, such as hospitalizations and emergency visits.”; (2) “Studies that incorporate increased longevity into spending projections suggest that cost offsets may diminish over time.”; and (3) “Strict benefit limits of all kinds decrease prescription drug use and increase use of other medical services, including acute and long-term care services.”

Baoping Shang, and Dana P. Goldman of the RAND Corporation; National Bureau of Economic Research (NBER) published results in 2007 from their study “Prescription Drug Coverage and Elderly Medicare Spending” (with preliminary results published in 2005) that examined Medicare Supplement (Medigap) enrollees with and without prescription coverage. They found that “Medigap prescription drug coverage increases drug spending by $170 or 22%, and reduces Medicare Part A spending by $350 or 13% (in 2000 dollars). Medigap prescription drug coverage reduces Medicare Part B spending, but the estimates are not statistically significant. Overall, a $1 increase in prescription drug spending is associated with a $2.06 reduction in Medicare spending.”