BACKGROUND: Whiplash is the most common type of injury reported in traffic accidents, but the effectiveness of conservative treatment for whiplash lacks evidence. AIMS: To assess the effect of early multidisciplinary evaluation and advice on the frequency of chronic neck pain three years post-injury in persons with minor or moderate traffic injuries. METHODS: In an insurance setting, we tested the effect by (1) a risk score matched prospective cohort design, (2) a propensity score matched nested case-control design and, (3) a risk and propensity score adjusted multivariate analysis in an unmatched prospective cohort design. We simulated unobserved risk and propensity factors to evaluate the robustness of the results for hidden bias. RESULTS: All three designs showed a significantly increased risk for chronic neck pain among those who received the intervention compared to those who did not. The relative risks ranged from 1.7 (95% CI: 1.0-2.6) to 2.6 (95% CI: 1.5-4.0). The results were robust to hidden bias. CONCLUSION: The consistency of the findings across the different designs strongly suggest that early multidisciplinary evaluation and advice increased the risk of having chronic neck pain three years following a minor or moderate traffic injury. Literally, the intervention may therefore have done more harm than good.
BACKGROUND: Whiplash is the most common type of injury reported in traffic accidents, but the effectiveness of conservative treatment for whiplash lacks evidence. AIMS: To assess the effect of early multidisciplinary evaluation and advice on the frequency of chronic neck pain three years post-injury in persons with minor or moderate traffic injuries. METHODS: In an insurance setting, we tested the effect by (1) a risk score matched prospective cohort design, (2) a propensity score matched nested case-control design and, (3) a risk and propensity score adjusted multivariate analysis in an unmatched prospective cohort design. We simulated unobserved risk and propensity factors to evaluate the robustness of the results for hidden bias. RESULTS: All three designs showed a significantly increased risk for chronic neck pain among those who received the intervention compared to those who did not. The relative risks ranged from 1.7 (95% CI: 1.0-2.6) to 2.6 (95% CI: 1.5-4.0). The results were robust to hidden bias. CONCLUSION: The consistency of the findings across the different designs strongly suggest that early multidisciplinary evaluation and advice increased the risk of having chronic neck pain three years following a minor or moderate traffic injury. Literally, the intervention may therefore have done more harm than good.