Background Pre-injury disability must be determined when assessing whether treatment programs return people to pre-injury status, however there is little empirical evidence to support recommendations that this be done as soon as possible after injury to prevent recall bias.

Objectives To determine disagreement between recall of pre-injury disability at different time points post-injury and bias towards under- or overestimating pre-injury disability.

Methods Self-reported pre-injury global disability was assessed within days, 6 months and 12 months post-injury in patients admitted to two level 1 adult trauma centres. Kappa statistics and multiple logistic regression models identified predictors of disagreement between time-points.

Results Pre-injury disability was measured at all time-points in 801 patients. Pre-injury disability at baseline was rated as none, mild, moderate, marked and severe in 80%, 12%, 5.1%, 1.9% and 1.0% respectively. Absolute agreement between baseline and 6 and 12 months respectively, was 79% and 80%. Corresponding kappa values (95% confidence intervals) were 0.33 (0.26−0.40) and 0.32 (0−25−0.38). Patients over 65 years or not completing high school were more likely to report less pre-injury disability at 6 and 12 months than at baseline with adjusted odds ratios (95% confidence intervals) for these groups being 8.24 (4.32−15.72) and 1.93 (1.03−3.64) respectively.

Conclusions There was little evidence of recall bias in an adult trauma population if self-reported global pre-injury disability was assessed 6 months post-injury. The recall of pre-injury disability up to 6 months post-injury can be used to determine return to pre-injury status, if assessment is not feasible shortly after injury.