Validity of Lithuanian Whiplash Study Questioned

By Editorial Staff

A paper by Schrader et al., "Natural evolution of late whiplash syndrome outside the medicolegal context," (Lancet, May 4, 1996;347:1207-11) concluded that whiplash injuries, and particularly late (chronic) whiplash are rare in countries where auto insurance and personal injury lawyers do not exist. The authors seemed to demonstrate that whiplash injuries are nearly nonexistent without the medicolegal incentives inherent in developed countries.

Overnight these findings appeared widely in newspapers and newsletters. The Association for the Advancement of Automotive Medicine [Inroads] carried a synopsis of the paper, as did the Back Letter, which featured a brief interview with Dr. David Cassidy. Dr. Cassidy viewed the study as valid, despite what he considered minor methodological problems.

In a few months, the Schrader et al. paper was regarded in many quarters as authoritative proof that whiplash is largely a symptom of avarice.

Some researchers pointed to what they considered significant flaws in the study's methodology (letters, July 13, 1996 Lancet, 348:124-126). Drs. Arthur Croft and Michael Freeman said there were serious problems with the authors' cohort selection. They asserted that because the study design was that of a retrospective cohort, the investigators were obligated to study a sample of persons exposed to a biologically credible causative agent. In the case of late whiplash, this agent would have been the presence of an acute whiplash. Drs. Croft and Freeman, after reviewing the cohort, found that only 15% had any signs of acute neck injury, and only two of 202 persons had symptoms for more than four weeks. As a result, they contend, only about 1% of the cohort would have been expected to be at risk of developing symptoms of late whiplash.

While Schrader et al. purported to have studied late whiplash syndrome, Drs. Croft and Freeman assert that they clearly did not, and thus rendered the study meaningless and impossible to interpret. The study was, as Drs. Croft and Freeman put it in Lancet, "fatally flawed."