To the Editor A study of vitamin D supplementation in pregnancy found the incidence of asthma and recurrent wheeze in offspring at age 3 years was lower by 6.1% compared with placebo.1 However, the 6.1% difference was not statistically significant and the trial was negative, but a reader would never know that reading the abstract.
The trial was designed to detect a 25% reduction in the incidence of asthma and recurrent wheeze in the first 3 years of life in the supplemented group, which is not mentioned in the abstract. The study concluded that it may have been underpowered. This was a negative trial. It appears to have been well done, the sample size was well thought out, and patients were adherent. Why then would the authors present these results as anything but negative and imply that more research is needed to examine this issue?
Merenstein D, D’Amico F. Prenatal Vitamin D and Offspring Wheezing. JAMA. 2016;315(24):2731. doi:10.1001/jama.2016.4111