Louis Lim

Project title: Clinical Outcomes After a Back Injury - Looking Beyound Injury Severity

Degree: MPH | Program: Occupational and Environmental Medicine (OEM) | Project type: Thesis/Dissertation
Completed in: 2011


The Department of Labor & Industries (L&I) provides no-fault workers' compensation insurance to the majority of workers in the state of Washington. For the fiscal years 1999 through 2003, work-related injuries involving the back and upper extremities resulted in a cost of 1.7 billion dollars. Most of the cost arises from a small number of claims that are characterized by escalating medical interventions and long term disability. Prior research has identified that patient and administrative factors predict administrative disability. However it is not certain which factors predict a lack of clinical improvement.

Identify risk factors associated with a poor clinical outcome one year after a work-related back injury, and determine the strength of the association between poor clinical outcomes and disability at one year.

Using the D-RISC study population, stratified by baseline Roland Morris Disability Questionnaire (RDQ) score (less severe impairment £ 12, more severe >12) and using bivariate analysis, we identified potential risk factors from eight domains associated with poor clinical outcomes. Factors found to be statistically significant were then entered into a two-step logistic regression model to determine which were associated with poor clinical outcomes.

For workers with less severe impairment at baseline, the factor associated with a poor outcome was the patient's own perception of the probability they would ever return to work (extremely negative expectation OR 11.0). In workers with more severe impairment, factors associated with poor outcomes also included race/ethnicity, age, number of pain sites (>4 pain sties OR 3.0), a previous back injury claim (OR 1.7), and injury severity (radiculopathy OR 1.8). When analyzed without stratification, RDQ score was also associated with a poor outcome. There was a strong association between a poor clinical outcome and one year administrative disability (OR >6).

This study demonstrates that there are multiple factors that can influence the clinical outcome in back injury. Further study is warranted to develop a predictive model that can be used to identify workers with high risk characteristics so that early intervention can be initiated to reduce the incidence of a poor clinical outcome.