Study design: Systematic review and meta-analysis.
Background: Whiplash-associated disorder (WAD) is the most common reported injury following motor vehicle accident. Evidence for prognosis and intervention are difficult to interpret due to differences in inception times, outcomes used, and sample heterogeneity.
Methods: An extensive literature search was conducted to identify published studies of prognosis following whiplash. Rigorous inclusion criteria were applied to allow for meaningful results to be drawn. Data were extracted, transformed where necessary, and pooled to allow estimation of the odds ratio for any factor with at least 3 data points in the literature.
Results: From 11 cohorts (n = 3193), 25 factors were identified with at least 3 data points in the existing literature. Of these, 9 were found to be significant predictors based on the odds ratio and confidence limits: no postsecondary education, female gender, history of previous neck pain,baseline neck pain intensity greater than 55/100, presence of neck pain at baseline, presence of headache at baseline, catastrophizing, WAD grade 2 or 3, and no seat belt in use at time of collision. Neck pain intensity, WAD grade, headache, and no postsecondary education were robust to publication bias.
Conclusions: Using a rigorous process for the identification and extraction of data from a homogenous subset of the prognostic WAD literature, we were able to identify several factors for which information is easy to collect clinically and could provide clinicians with a good sense of prognosis following whiplash injury.