Background: Studies of low back pain (LBP) disability remain largely incomparable because of different outcome definitions. To date, systematic comparisons of alternative outcome measures have not been made.
Methods: Duration of work disability was studied in a 3-year cohort of 850 workers' compensation LBP claimants. Eleven administrative outcome measures were compared using Kaplan-Meier estimates of the proportion of claimants still on disability benefits during 3.5 years of follow-up.
Results: The estimated mean duration of work disability was 75 days for the first temporary disability (TD) episode, 108 days for cumulative time on TD, and 337 for total compensated days, which includes all types of wage replacement benefits during vocational rehabilitation, temporary and permanent disability.
Conclusions: Commonly used administrative measures of lost workdays--time to first return to work and time on temporary disability--substantially underestimate the duration of work disability compared to measures based on all wage replacement benefits.