What is different about worker's compensation patients? Socioeconomic predictors of baseline disability status among patients with lumbar radiculopathy

STUDY DESIGN. Combined analysis of 2 prospective clinical studies. OBJECTIVE. To identify socioeconomic characteristics associated with workers' compensation in patients with an intervertebral disc herniation (IDH) or spinal stenosis (SpS). SUMMARY OF BACKGROUND DATA. Few studies have compared socioeconomic differences between those receiving or not receiving workers' compensation with the same underlying clinical conditions. METHODS. Patients were identified from the Spine Patient Outcomes Research Trial (SPORT) and the National Spine Network (NSN) practice-based outcomes study. Patients with IDH and SpS within NSN were identified satisfying SPORT eligibility criteria. Information on disability and work status at baseline evaluation was used to categorize patients into 3 groups: workers' compensation, other disability compensation, or work-eligible controls. Enrollment rates of patients with disability in a clinical efficacy trial (SPORT) and practice-based network (NSN) were compared. Independent socioeconomic predictors of baseline workers' compensation status were identified in multivariate logistic regression models controlling for clinical condition, study cohort, and initial treatment designation. RESULTS. Among 3759 eligible patients (1480 in SPORT and 2279 in NSN), 564 (15%) were receiving workers' compensation, 317 (8%) were receiving other disability compensation, and 2878 (77%) were controls. Patients receiving workers' compensation were less common in SPORT than NSN (9.2% vs. 18.8%, P < 0.001), but patients receiving other disability compensation were similarly represented (8.9% vs. 7.7%, P = 0.19). In univariate analyses, many socioeconomic characteristics significantly differed according to baseline workers' compensation status. In multiple logistic regression analyses, gender, educational level, work characteristics, legal action, and expectations about ability to work without surgery were independently associated with receiving workers' compensation. CONCLUSION. Clinical trials involving conditions commonly seen in patients with workers' compensation may need special efforts to ensure adequate representation. Socioeconomic characteristics markedly differed between patients receiving and not receiving workers' compensation. Identifying the independent effects of workers' compensation on outcomes will require controlling for these baseline characteristics and other clinical features associated with disability status.