Sudden unexpected death in infancy: epidemiologically determined risk factors related to pathological classification

Infants,that died suddenly and unexpectedly were studied as part of the Eur opean Concerted Action on sudden infant death syndrome (SIDS). Three paedia tric pathologists, first independently of each other and later in a consens us meeting, classified 63 cases into 3 groups: SIDS (19 cases), borderline SIDS (30 cases) and non-SIDS (14 cases). The interobserver agreement among the pathologists before the consensus meeting was moderate (Kappa = 0.41) a nd jointly it was higher (Kappa = 0.83). The distribution of epidemiologica lly determined risk factors was studied over these three groups. Maternal s moking after birth, low socioeconomic status and thumb sucking were found m ore often in SIDS than in the other cases. Inexperienced prone sleeping was a determinant for SIDS, but not for non-SIDS. Previous hospital admission, low birthweight and/or short gestation were associated with borderline SID S. Non-SIDS cases received more breastfeeding, the parents hardly smoked du ring pregnancy and after birth, a firm mattress had been used, and more oft en signs of illness had been reported by the parents, compared with the SID S and borderline SIDS cases. Bedding factors and both primary and secondary prone sleeping were equally distributed over the three groups which suppor ts the hypothesis that, in SIDS and borderline SIDS, as well as in non-SIDS cases, some similar external and preventable factors might influence the e vents leading to death. Research should therefore focus on all sudden unexp ected deaths, after which subgroups such as SIDS cases can be separately an alysed. The postmortem is an essential part of the whole work-up of each ca se and the results should be interpreted with all other available data to a rrive at a sound evaluation of cases and thus form the basis for the preven tion of all sudden unexpected infant death.