OUTCOME OF LUMBAR FUSION IN WASHINGTON-STATE WORKERS COMPENSATION

Study Design. This study covered a large, population-based cohort of workers in the Washington State workers' compensation system who received lumbar fusion between August 1, 1986 and July 31, 1987 to determine work disability status, reoperation rate, and patient satisfaction. Objectives. To use predictors of outcome of lumbar fusion to design clearer clinical guidelines for lumbar fusion in injured workers. Methods. Logistic regression analysis was used to determine the predictors of work disability and risk of reoperation after fusion. Results. The lumbar fusion incidence rate was 41.7/100,000 workers a year (n = 388 patients). Overall, 68% were work disabled and 23% required further lumbar spine surgery 2 years post-fusion. Five markers of severity predicted worse work disability outcome (older age at injury, longer time from injury to fusion, increased time on work disability before fusion, increased number of prior low back operations, and increased number of levels fused). Even after adjusting for these variables, receiving instrumentation with fusion doubled the risk of reoperation. Most patients reported that back pain (67.7%) was worse and overall quality of life (55.8%) was no better or worse than before surgery. Conclusions. Outcome of lumbar fusion performed on injured workers was worse than reported in published case series. Prospective studies should be conducted to determine the biologic indications that might lead to improved outcomes in this disabled population.