Medicare audits often include a statistical extrapolation to estimate the full extent of an alleged overpayment. Medicare contractors are authorized to review the merits of only a small “sample” of submitted claims and extrapolate the results of that review to a large “universe” of claims to estimate the overpayment amount. This practice can lead contractors to allege overpayments of hundreds of thousands or millions of dollars despite only reviewing and denying a small handful of claims. Medicare contractors generally have broad authority to use a wide array of statistical methods when extrapolating the overpayment amount, which can lead to grossly overestimated overpayment determinations.
When conducting the statistical sampling and extrapolation, the contractor will select the period for review and establish the universe and sample frame. The sample frame is the large group of claims from which the sample is randomly selected, and the universe is the group of claims over which the results of the review are projected. The sample frame and universe may or may not be identical. The universe and sample frame may be defined by specific codes, dates of services, beneficiaries, or some combination thereof. From here, the contractor will select a random sample from the sample frame, review the claims within the designated sample, and extrapolate the results of the review of the sample to all claims in the established universe.
A statistical extrapolation is subject to appeal, similar to any Medicare overpayment determination. However, there are several issues unique to appealing a statistically extrapolated overpayment. First, it adds increased importance to appealing the denial of each claim in the sample. While an individual claim may not represent significant monetary value on its own, it may represent tens of thousands of dollars after it has been statistically projected over a large universe. Second, there are special procedural rules for appealing an extrapolation. For example, providers are generally prevented from arguing before an Administrative Law Judge (ALJ) that the extrapolation was flawed unless they included specific language in their request for ALJ review.