To the Editor:—
In response to the hypothesis that prolonged exposure of neonates to anesthetic drugs causes long-term neurocognitive deficits in humans, as it seems to do in mice and rats,1Soriano et al. 2published a graph of the IQs at ages 4 and 8 yr of children who had undergone surgical repair of congenital heart defects as neonates using a standardized anesthetic regimen including high-dose barbiturates and opiates. Those IQ results were interpreted as showing “no significant differences between the study groups and the population norms.”2
The graphical representations of the IQ data are not accurate, but the means and SDs can be obtained from table 5 of Ferranti et al. 3At both 4 and 8 yr of age, the full-scale IQs of children exposed to sustained anesthesia as neonates were statistically significantly lower than population norms (P < 0.0001 and P < 0.02, respectively). The 95% confidence interval at age 4 yr is 90.2–94.9, and the 95% confidence interval at age 8 yr is 94.7–99.5. The 95% confidence interval for age 8 yr includes the risk of an IQ decrement of one third of an SD. The 95% confidence interval at age 4 yr indicates that a one-third SD decrement is highly probable, and it includes the risk of a two-thirds SD decrement.
Statistical significance notwithstanding, clinical significance is often in the eye of the beholder. In the eye of this beholder, these data do not argue against the hypothesis that the data obtained in rodents apply to humans.
State University of New York, Brooklyn, New York. firstname.lastname@example.org