Government study compares FIM, MDS-PAC

HCFA contractors have begun collecting data

Although no one can say for certain that Medicare will switch rehab patient classification systems until the prospective payment system (PPS) proposed rule is published, it’s clear the government is seriously considering a change.

The Health Care Financing Administration in Baltimore funded a nine-month project to evaluate the Minimum Data Set-Post Acute Care (MDS-PAC) for use in classifying cases into case mix groups in inpatient rehabilitation PPS. The study will compare MDS-PAC with the Functional Independence Measure-Functional Related Groups (FIM-FRGs).

Fifty facilities nationwide started to collect data in September. On all Medicare, non-HMO admissions, the rehab sites will collect both MDS-PAC and FIM data at admission for all patients with stays beyond three days in an eight-week period.

"The purpose of the study is to see if the two instruments classify patients into the same payment cells," says Joan Buchanan, PhD, a lecturer in health care policy at Harvard Medical School in Boston. Buchanan is the study’s principal investigator. The project is a collaborative effort by Harvard Medical School, Rand Corp., and Sargent College of Health and Rehabilitation Sciences at Boston University in Boston.

"There already are costs attached to payment cells, so if the two systems don’t classify cases in the same way, there’s potentially an issue of fairness of payment to hospitals or access to patients," Buchanan says.

Study to examine consistency

The study will determine the following:

  • How accurate is the MDS-PAC for use in classifying cases into case mix groups under the inpatient rehab PPS?
  • How does the MDS-PAC compare in validity, reliability, and consistency with the FIM?
  • Do the FIM and MDS-PAC code comorbidities accurately?
  • Does the MDS-PAC provide an opportunity for better groupings in future classification work because of its additional data?

The study’s design will address psychometric issues to ensure that institutions across the country are calibrating to the same set of norms and to obtain the most reliable data. Three calibration teams visit each participating institution, spending 2.5 days at each site and rating at least four cases using both the FIM and MDS-PAC systems.

The project is scheduled to be completed by March 31, 2001. 

Need More Information?

  • Joan Buchanan, PhD, Principal Investigator, Department of Health Care Policy, Harvard Medical School, 180 Longwood Ave., Boston,
    MA 02115. Telephone: (617) 432-0449. E-mail: