ALTEs Linked to SIDS?
Esani N, Hodgman JE, Ehsani N, Hoppenbrouwers T
J Pediatr. 2008;152:365-370

The authors evaluated the case histories of 153 infants who participated in a US multicenter infant home monitoring study (Collaborative Home Infant Monitoring Evaluation [CHIME]). Their goal was to determine the factors associated with apparent life-threatening events (ALTEs) to test the hypothesis that the risk factors for experiencing an ALTE were different from the known risk factors for sudden infant death syndrome (SIDS). There is disagreement over whether ALTEs are really precursors to SIDS or occur as unrelated phenomena.

The infant home monitoring study was completed between 1994 and 1998, but infants were not followed for uniform lengths of time. Of the infants studied here, 70% remained in the original study for at least 4 months.

Infants were enrolled in the original study if they experienced an ALTE: apnea, color change, muscle tone change, gagging, choking, or vomiting and vigorous stimulation was required or delivered and no other cause for the episode was identified on medical evaluation. Roughly 2/3 of the infants required vigorous stimulation at the first presentation, and 24% received rescue breaths.

The authors identified 5 contemporaneous studies of SIDs for comparison of risk factors. The sample was 12% African American, 10% Hispanic, 14% native Hawaiian, Native American, or Samoan, with the remainder being white. The studies looked at anywhere from 185 to over 10,000 subjects (with a total almost 14,000 subjects).

In comparing the characteristics of the cohort who experienced an ALTE to those who had risk factors for SIDS, the authors noted that there was less of a male predominance in ALTE patients (52% male vs approximately 60% of SIDS patients in 4 studies). ALTE subjects were also less likely to be low birthweight (12% vs approximately 20% in 2 SIDS studies). In addition, only 9% of ALTE patients were small for gestational age compared to 15%-19% of the SIDS patients.

Investigators did not find significant differences in rates of prematurity, multiparity, maternal age, or maternal smoking status between the 2 groups. Finally, there was a notable age difference at the time of event between the ALTE and SIDS patients, with 74% of ALTEs occurring before the infants were 2 months old, compared to approximately 25% of SIDS cases.

The authors conclude that there are enough differences in infants with ALTEs compared to historical SIDS risk factors that these data do not support a link between the 2 processes.

This study is very thought-provoking but does not provide the last word on comparison of ALTE and SIDS. The data from SIDS patients were not collected from the same sites as those of the ALTE patients, and the collection methods were likely very different. In addition, only 31% of infants in the ALTE study were followed up to 6 months, so the ability of the ALTE study to identify later SIDS cases is diminished. That said, the age difference between ALTE and SIDS patients and the different rates of small for gestational age are perhaps the 2 most interesting correlations. It would be very interesting to confirm this possible age discrepancy in data that followed ALTE children longer.

Abstract