Background: 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.
Methods: 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.
Results: 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.
Conclusions: 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
Level of Evidence: Prognostic Level I. See Instructions
to Authors for a complete description of levels of evidence.