High pain ratings predict treatment failure in chronic occupational musculoskeletal disorders

Pain intensity is one of the most widely used measures in the treatment of patients with chronic disabling occupational musculoskeletal disorders. Few studies have comprehensively investigated the relationship of pain intensity at the time of rehabilitation to objective socioeconomic outcomes at one year after treatment. This study evaluated the ability of pain intensity ratings, measured with a visual analog scale, to predict rehabilitation outcomes and to identify patients who are "at risk" for a poor outcome.

A cohort of 3106 patients with chronic disabling occupational musculoskeletal disorders in a multidisciplinary occupational tertiary rehabilitation program was divided into four groups on the basis of the pain intensity ratings (0 to 3, 4 to 5, 6 to 7, and 8 to 10) before and after rehabilitation. A structured interview to assess the socioeconomic outcomes, including work status, health-care utilization, recurrent injury, and whether there had been resolution of Workers' Compensation or third-party financial disputes, was conducted one year after rehabilitation.

High pain intensity before rehabilitation was linearly associated with declining rates of program completion and higher rates of self-reported depression and disability after rehabilitation. Although higher pain ratings both before and after rehabilitation were associated linearly with a declining quality of socioeconomic outcomes, extremely high pain ratings (8 to 10) after rehabilitation were most predictive of poor outcomes. At the post-rehabilitation evaluation, patients with extreme pain were far more likely than those with mild pain to seek surgical treatment (risk ratio = 11.2 [95% confidence interval, 4.3, 29.5]) or to persist in seeking health care from new providers (risk ratio = 3.3 [95% confidence interval, 2.4, 4.5]). They were less likely to either return to work (risk ratio = 3.9 [95% confidence interval, 2.6, 6.0]) or to retain work (risk ratio = 4.2 [95% confidence interval, 2.9, 6.0]). They were also twice as likely to claim a new injury to the same musculoskeletal site after returning to work and to fail to settle Workers' Compensation or third-party financial disputes.

High pain ratings before rehabilitation are associated with higher rehabilitation dropout rates. The patients with chronic disabling occupational musculoskeletal disorders who reported extreme pain after completing a full course of extended treatment (13% of 2573) were at risk for poor outcomes in terms of lost productivity, high utilization of health care, and cost-shifting of state Workers' Compensation payments to federal resources.