Dr. Näyhä Replies

To the Editor: I thank Dr. Smith for his comments. Some of the women who died on Friday the 13th were, of course, injured some days previously. This would not invalidate my argument. It is sufficient that in some proportion of the cases, the accident and the death occurred on the same day. During the 1970s, 75% of the people killed as a result of traffic accidents in this country died at the scene of the accident or en route to the hospital (1), and an additional proportion died in the hospital on the same day. The percentage of more or less immediate deaths may have declined now because of improved emergency services, but more recent data are difficult to come by. In Denmark, where distances are short, 68% of the persons who died in traffic in 1986–1991 were dead upon arrival at the emergency unit, and 88% died within the first day (2). Comparable proportions of quick deaths in this case would be sufficient to provide a sound basis for the conclusion reached in my article.

The suggestion that superstition-related anxiety might cause a degradation in vital bodily functions is interesting but would presuppose a higher risk due to Friday the 13th in older age groups than in younger ones. A reanalysis of female deaths broken down into the age bands of 15–34, 35–54, 55–74, and ≥75 years showed risk ratios of 2.51 (95% confidence interval [CI]=1.45–4.36), 1.26 (95% CI=0.59–2.70), 1.32 (95% CI=0.74–2.36), and 1.36 (95% CI=0.54–3.44), respectively. Since an elevated risk was more typical of young women who have less driving experience, an explanation based on driving errors would seem more likely.

Possible flaws, listed in the article, include deaths of passengers, who obviously cannot be part of the causal chain, and it is also difficult to see why drivers (men or women) beset by this superstition would select women as their victims. Dr. Smith presents an additional problem that cannot be solved without a large study linking accidents to subsequent deaths. So far, any explanations must remain speculative.