Comparing methods to identify hip fracture in a nursing home population using Medicare claims.

UNLABELLED: The inpatient principal diagnosis in Medicare claims identified 96% of hip fractures in hospitalized nursing home residents with high rates of confirmation by other claims files.
INTRODUCTION: Hip fracture is typically identified in Medicare claims by examining only the principal diagnosis in the inpatient file, but this simple approach might be inadequate for nursing home residents. Our objective was to examine the impact of varied operational definitions for identifying hip fracture hospitalizations in administrative claims data.
METHODS: We conducted a retrospective examination of Medicare inpatient and outpatient claims data for dually Medicaid- and Medicare-eligible nursing home residents in 1999 in California, Florida, Missouri, New Jersey, and Pennsylvania (n = 197,514). We determined the number of hip fractures identified in inpatient (Medicare A) diagnoses codes using differing definitions that varied according to whether or not hip fracture was required to be the principal diagnosis and whether or not confirmatory imaging and procedure codes were required to be found in other (Medicare B) claims files.
RESULTS: Hip fractures were found in any inpatient diagnosis position in 4,680 subjects, with 4,479 of these found in the principal diagnosis position. With either approach to diagnosis position, confirmatory imaging and procedure codes were identified for 95% of persons hospitalized with hip fracture.
CONCLUSION: The principal diagnosis alone will identify 96% of hip fracture diagnoses in hospitalized nursing home residents. Such diagnoses are confirmed at very high rates by other sources of claims data. Researchers may be confident using a simple approach to identifying hip fracture hospitalizations in this population, using inpatient claims alone and interrogating only the principal diagnosis position.