Impact of a worker's compensation practice guideline on lumbar spine fusion in Washington State

Abstract

Objectives: In the face of escalating medical costs for injured workers, the Washington State Department of Labor and Industries (L&I), which pays for most workers' compensation costs in the state, established guidelines for elective lumbar fusion as part of its inpatient utilization review program. The guidelines were tied to reimbursement strictures. The authors attempt to assess the effects of these guidelines, which were introduced in November 1988, upon subsequent L&I fusion procedures.

Methods: Discharge data from the Comprehensive Hospital Abstract Reporting System and algorithms using International Classification of Diseases, Version 9, Clinical Modification diagnosis and procedure codes were used to identify lumbar surgical cases. Population estimates were from the 1990 US Census Bureau.

Results: During the period of years 1987 through 1992, the lumbar fusion rate for the state showed a 26% decline compared with a 3% decrease for all lumbar operations. After November 1988, when the guidelines went into effect, the state fusion rate declined 33%, whereas rates for nonfusion operations essentially were unchanged. The sharpest decline corresponded in time to implementation of the guidelines. Prior to the initiation of L&I guidelines, the proportion of fusions among L&I patients was higher than among non-L&I patients. The opposite was true by the end of 1992, and the L&I proportion decreased more rapidly than the non-L&I proportion. Time series analysis revealed that both the decline in Washington state lumbar fusion rates and the decline in the proportion of lumbar fusion among L&I patients were statistically significant.

Conclusions: The data suggest that the L&I lumbar fusion surgery criteria and reimbursement standards implemented in 1988 contributed to a decline in rates of performing that procedure. The utilization review aspect of the guidelines as well as the process of involving surgeons in the preparation and dissemination of guidelines also may have been contributory.