Prognostic factors for time receiving workers' compensation benefits in a cohort of patients with low back pain.
METHODS
Prospective inception cohort study.


OBJECTIVE
To develop a prognostic model that predicts time receiving workers' compensation benefits for low back pain claimants.


BACKGROUND
As the cost and difficulty of managing low back pain escalate, any predictor of outcome is advantageous.


METHODS
To obtain the outcome and predictor variables, patient data from two separate databases were linked: a clinical database and an administrative (Ontario workers' compensation) database. Claimants injured between January 1 and December 31, 1994, were included and observed for 1 year from the date of accident. The outcome variable was cumulative number of calendar days receiving benefits.


RESULTS
Multivariable Cox proportional hazards regression (forward stepwise) showed eight significant predictors; five were associated with increased time receiving benefits compared with their reference groups: 1) working in the construction industry, 2) older age, 3) lag time from injury to treatment, 4) pain referred into the leg, and 5) three or more positive Waddell nonorganic signs. Three predictors were associated with reduced time receiving benefits: 1) higher values of questionnaire score, 2) intermittent pain, and 3) a previous episode of back pain. A predictive score was calculated to categorize claimants as at high or low risk for chronicity. When an arbitrary cutoff point was set at the 75th percentile of predictive score, negative predictive value was 94%.


CONCLUSIONS
This research identified eight factors for time receiving workers' compensation benefits among claimants with low back pain. This model discriminates between high- and low-risk claimants. Few low-risk claimants continued to receive benefits for more than 3 months.
McIntosh
G
G
Department of Public Health Sciences, University of Toronto, Canada. gmcintosh@cbi.ca
Frank
J
J
Hogg-Johnson
S
S
Bombardier
C
C
Hall
H
H
D000328:Adult; D005260:Female; D005544:Forecasting; D006801:Humans; D016015:Logistic Models; D017116:Low Back Pain / Q000191:economics* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D011446:Prospective Studies; D012044:Regression Analysis; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014942:Workers' Compensation / Q000191:economics*