OIG defends HCFA’s practice of statistical sampling of part A providers
By MATTHEW HAY
HHBR Washington Correspondent
WASHINGTON The Office of Inspector General’s (OIG) recent point-by-point assessment of the U.S. Senate Committee on Small Business’ request for evaluation of Medicare Part A provider statistical sampling and projection methodology offers a strong defense of current Health Care Financing Administration (HCFA; Baltimore) practices in that area.
The committee’s request was prompted by concerns raised by HCFA employee Martha Mayes John, who challenged the fairness of the statistical sampling methods that Medicare contractors use in estimating overpayments made to hospitals and other Medicare Part A providers, including home health agencies.
Johnson argued that HCFA’s faulty methodology was adversely affecting providers. However, HCFA Deputy Inspector General for Audit Services Thomas Roslewicz said the OIG’s examination concluded that HCFA’s methodology is both sound and fair. In fact, the OIG came down on the agency’s side on every point raised by Johnson.
For example, HCFA said that Johnson’s contention that sample sizes of 100 are not large enough to adjust for precision considerations is incorrect. HCFA had argued that depending on the parameters of the target population, such a sample size would be quite adequate, while in other situations it will be better to increase the sample size.
The OIG weighed in on HCFA’s side on this point, noting that relatively few court cases address the adequacy of sample sizes in Medicare or Medicaid cases.
"So long as a provider/supplier has an opportunity to contest the sampling procedures and the audit determinations, a small sample size will not invalidate a proposed disallowance," said the OIG.
Likewise, the OIG disagreed with Johnson’s contention regarding mixed sampling units. Johnson argued that if a sample of claims is taken from a defined universe of claims, it can only be projected back to that universe of claims and not to a sample visit. But HCFA countered that it is appropriate to use a fixed number of claims if it is computing the number of dollars denied per claim.
The OIG responded that there is usually more than one way to design a sample to meet a specific objective. "To meet HCFA’s objective, a claim is an appropriate sampling unit," the OIG concluded. "The sample of claims can be used to estimate the dollar amount which has been overpaid, as well as the number of visits denied."
The Small Business Committee had no immediate response to the OIG’s report.
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