Clinical Outcomes in Worker's Compensation Patients: A Case-Control Study

Introduction: The purpose of this study is to compare clinical outcomes after lumbar fusion in patients receiving workers compensation (WC) to a case-matched control group.

Methods: From 783 patients who had posterolateral fusion,, 60 WC patients were identified. Outcome measures were the Oswestry Disability Index (ODI), Short Form 36 (SF-36), back and leg pain numeric rating scales. The Propensity scoring technique was used to match WC patients to a control group( not on WC) using gender, age, smoking status, BMI, diagnosis, number of levels fused, pre-op ODI, SF-36 PCS, SF-36 MCS, back and leg pain scores producing 58 matched pairs.

Results: There were no significant differences between the demographics and pre-operative outcome scores in the two groups. At two-years post-op, non-WC patients had a significantly greater improvement in ODI, SF-36 PCS and back pain scores compared to WC patients. The mean two year ODI, SF-36 PCS and back pain scores of WC patients were significantly lower than the non-WC patients. 11 of 58 (19%) WC patients reached the ODI minimum clinically important difference (MCID, ODIe12.8) compared to 21 of 58 (36%) non-WC patients (p=0.061). Only 9 of 58 (16%) WC patients reached SF-36 PCS MCID (PCSe4.9) compared to 23 of 58 (40%) non-WC patients (p=0.006).

Discussion and Conclusion: After controlling for covariates known to affect outcomes after lumbar fusion, , patients on WC have significantly less clinical outcome improvements in ODI, SF-36 PCS and back pain scores as well as the number of patients achieving substantial clinical benefit.