Measuring the Impact
By tracking patients longitudinally, and ensuring that we have captured all of their prescriptions, Amundsen has been able
to mimic the Part D insurers' calculation of cumulative drug spend and out-of-pocket cost sharing for a given patient, thereby
having a reasonable estimate of when they should have reached the $2,400 limit in 2007 ($2,250 in 2006).
From the 3 million patients in the Verispan/Amundsen coverage gap database, it was estimated that approximately 72 percent
of nonsubsidy patients and 83 percent of total enrollees do not have a coverage gap, or do not reach the cumulative drug spend
that would put them in the gap. LIS patients, who had very distinctive branded copays of $3.10 and $5.35 in 2007, and who
have no exposure to the coverage gap, account for about 38 percent of enrollees and frequently are a higher proportion of
the prescriptions in any given class.
Of the remaining 18 percent of patients who actually reach the $2,400 threshold, about half are actually paying full price
for all their drugs. The remaining half have either full coverage or some gap coverage. Plans with some gap coverage may be
"generics only," or have identified a number of branded drugs that are apparently exempted. The number having full coverage
in the gap remains a bit of a surprise, and the explanation for its importance varies by therapeutic class and Part D region.
These percentages will be very different for any cohort of patients who might be taking a particular class of drugs. Take
branded proton pump inhibitors (PPIs) as an example. Because branded PPIs have relatively high negotiated prices, and because
PPI patients in Part D have many comorbid conditions, a higher percentage of PPI patients reached the coverage gap in 2007—29
percent, compared with 18 percent in the group as a whole. Of the nonsubsidy PPI patients who reach the threshold, more than
one-third will have coverage for virtually all of their medications. Another group will have some gap coverage for generics
only, or for some branded products.
To measure how much impact the coverage gap has had on each of the cohorts that experience exposure to the coverage gap, Amundsen
used a standard methodology that benchmarks the persistence, compliance, adherence, and generics substitution of each exposed
cohort against a group that should not be affected—those who have full coverage in the gap. For example, we would expect to
see a reduction in the share of branded PPIs as plans and consumers put more emphasis on generic omeprazole. Both the LIS
cohort and those PPI patients with full coverage increased their utilization of generics by about 5 market share points over
the 12 months of 2007. Those in the exposed cohorts, on the other hand—those with no gap coverage, some branded coverage,
or generics coverage—shift 10 to 15 market share points to generics over the same time period.
Asking the Wrong Question
What pharmaceutical executives really want to know is how many days of therapy they might be losing from Part D patients as
a result of this feature of the benefit design. In seeking this information, most marketing and sales people in the industry
have focused their attention solely on those who may have exceeded the coverage threshold for a given year.
But to truly understand the impact of the coverage gap, you have to consider other groups as well—particularly those who don't
reach the $2,400 limit, LIS patients who have no gap in coverage, and the sickest Part D patients who have spent $3,850 out
of pocket and thus qualify for catastrophic coverage with lower copays. For each patient cohort you want to know:
How many? Number of patients, average number of prescriptions per year
How much? Percentage of days of therapy lost after reaching the coverage gap?
For how long? Number of months affected