Lumbar disc surgery in a fixed compensation population: a model for influence of secondary gain on surgical outcome.

Background: Reported outcomes in patients undergoing surgical procedures for lumbar disc herniation are poorer in patients eligible for workers' compensation or with pending litigation. In the civilian community, the amount of compensation for one's disability is variable and thus its influence on surgical outcome is difficult to quantify. In the military, all members are covered by a standardized workers' compensation system, and have generally standardized work requirements, a standard pay scale, and third party evaluation of disability based on the Veterans Affairs rating system. This made the military a good system in which to study the effect of potential compensation on surgical outcome.

Methods: The study population consisted of active duty military members who underwent sequential lumbar microdiscectomies over a 31-month period. Omitted were lumbar fusions, decompressive laminectomies, and far lateral discectomies. Clinical and demographic variables, along with financial data for each patient were derived from these data. A good result was defined as return to active military duty.

Results: Three hundred forty-nine lumbar discectomies were performed in 348 active duty military members. Overall, 75.3% (262) of the 348 patients were able to return to full military duty after surgery, and 24.7% (86) received disability compensation. Chi-square univariate analysis showed higher compensation incentive was a significant determinant of poor surgical outcome (p = 0.0021). The influence of compensation incentive was proportional to the amount of anticipated payout, and relative to a military service member's usual income. In mutivariate analysis, lower base pay (0.0005) and female gender (p = 0.038) were predictive of poor outcome.

Conclusions: Secondary gain in the form of disability pay has a proportionally adverse effect on outcome following lumbar disc surgery. Although studying this issue in the military system allowed standardization of secondary gain values, the influence of other factors could not be eliminated entirely. Potential disability pay is proportionally greater in lower ranked service members. Thus, other variables such as income level, education, and job satisfaction may contribute to the poorer results in this subgroup of military members.