Healthy children who undergo a single episode of general anesthesia before age 36 months show no statistically significant differences in IQ scores later in childhood compared with their unexposed siblings, a new study suggests.

“There was no significant difference in IQ scores between the children who were exposed to anesthesia and siblings who were not,” lead author Lena S. Sun, MD, said in a Columbia University Center news release. “We also saw no difference in most of the secondary outcomes, although more children in the group exposed to anesthesia exhibited internalizing behavior that required further clinical evaluation. That’s an area that needs to be further explored.”

Dr Sun, from the Morgan Stanley Children’s Hospital–New York Presbyterian, Columbia University Medical Center, New York City, and colleagues present their findings in an article published online June 6 in JAMA.

The study included 105 sibling pairs; one sibling in each pair had undergone a single exposure to general inhaled anesthetic (43 sevoflurane, 5 isoflurane, and 57 both sevoflurane and isoflurane) for inguinal hernia repair before age 36 months. The children underwent assessment at ages 8 to 15 years for the primary analysis of an increased risk for impaired global functioning. Between 97 and 105 sibling pairs also underwent analysis for the secondary outcomes of abnormal domain-specific neurocognitive functions and behavior.

Overall, the mean IQ scores were similar between the exposed cohort (full-scale IQ, 111 [95% confidence interval (CI), 108 – 113]; performance IQ, 108 [95% CI, 105 – 111]; verbal IQ, 111 [95% CI, 108 – 114]) and the unexposed siblings (full-scale IQ, 111 [95% CI, 108 – 113]; performance IQ, 107 [95% CI, 105 – 110]; verbal IQ, 111; 95% CI, 109 – 114]).

In addition, the between-group differences were not statistically significant when the researchers divided the cohort according to age of exposure: 0 to 11 months (full score difference, 1; 95% CI, −4.1 to 6.1), 12 to 23 months (1; 95% CI, −3.4 to 5.4), and at 24 to 36 months (−1; 95% CI, −5.8 to 3.8). Similarly, there was no significant differences seen when the researchers stratified the group based on duration of exposure: 0 to 59 minutes of exposure (full score difference, 2; 95% CI, −4 to 8), 60 to 119 minutes of exposure (0; 95% CI, −3.4 to 3.4), and 120 or more minutes of exposure (−2; (95% CI, −8.2 to 4.2).

A number of children received general anesthesia after 36 months (18 exposed and 23 unexposed siblings); however, subset analyses taking these later exposures into account did not alter the primary finding.

Secondary Outcomes

Statistically significant differences were found between exposed and unexposed siblings in terms of verbal fluency (difference, −1; 95% CI, −1.7 to −0.3); behavior (Child Behavior Checklist; internalizing: difference, 3.2 [95% CI, 1.1 – 5.3]; externalizing: difference, 2.1 [95% CI, 0 – 4.2], and total problems: difference, 2.7 [95% CI, 0.6 – 4.7]); and adaptive behavior (Adaptive Behavior Assessment System, Second Edition; social composite: difference, −3.3; 95% CI, −6.1 to −0.6).
There were no statistically significantly differences between siblings in the remaining secondary outcomes of domain-specific neurocognitive functions of memory, learning, motor or processing speed, visuospatial function, attention, language, executive function, and other areas of adaptive behavior.

“Differences in mean behavior scores between exposed and unexposed siblings became statistically nonsignificant after adjustment for sex. However, even after adjustment for sex, more exposed children had clinically abnormal internalizing behavior scores than unexposed siblings. With the limited number of exposed girls and same-sex female sibling pairs, further analysis to examine the apparent sex exposure interaction in behavior was not possible,” the authors write.