1. In a nationwide cohort study in Denmark, a higher rate of sudden infant death syndrome (SIDS) observed among siblings of children who died of SIDS

2. Genetic and environmental factors should be investigated in those who have siblings that died of SIDS

Evidence Rating Level: 2 (Good)

Sudden infant death syndrome (SIDS) is a leading cause of death in the first year of life, however the mechanisms are unclear, making prevention a challenge. Although previous studies have described a positive family history, they were on select populations. This nationwide study involved a population of 266 834 consecutive births during a 39-year study period. Of this group. 1540 infants died of SIDS and 2384 younger siblings were identified to these cases. The main outcome was standardized incidence ratios (SIRs) of SIDS. Other characteristics including maternal educational status and household income were also assessed. It was found that most cases of SIDS (90%) occurred within the first six months of life. Between SIDS index cases and the general population, there were no significant differences in sex of child and mother’s age at childbirth. It was found that siblings of SIDS index cases were more likely to live in low-income households (50% vs 30%) and have mothers with only an elementary school education (54% vs 26%) compared to the general population. After adjusting for sex, age and calendar year, a higher rate of SIDS was seen in siblings compared to the general population with a SIRS of 4.27 (95% CI, 2.13-8.53). With further adjustment for mother’s age and education, a SIRS of 3.50 was seen. This study shows that shared genetic and environmental factors may play a role in SIDS. This study is limited in the fact that the results were not statistically significant. Future studies involving larger population sizes as well as those investigating more specific genetic and environmental factors are needed to identify any modifiable risk factors contributing to SIDS.

Click to read the study in JAMA Network Open

Image: PD

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