Risk factors related to hearing impairment and screening with the Crib-O-Gram

A "Crib-O-Gram" was employed for an automatic screening of hearing impaired newborns. A series of 502 neonates were tested, and 57 babies were judged to be "REFER." These "REFER'd" subjects were further examined with ABR, and 4 hearing impaired subjects were found. A detailed history was available in 427 neonates, and "risk factors" related to hearing impairment were investigated. The incidence of "REFER" judgment was found to be significantly higher for the group of neonates with risk factors than for those without risk factors. The rate of "REFER" judgment was computed for each risk factor, and the phi-coefficient of association was calculated to study the statistical relationship between the "REFER" judgment and each risk factor. A significant relationship was confirmed for anatomic malformations, positive family history of deafness, and congenital perinatal infection. The relationship between the existence of hearing impairment and each risk factor was similarly studied. Congenital perinatal infection and family history of deafness were significantly associated with hearing impairment, although anatomic malformation was not significantly related. The quantification theory (Hayashi type II) was applied to calculate a relative weight of each risk factor in reference to both the REFER judgment and hearing impairment. It was pointed out that proper weighting of each risk factor may be useful in improving the efficiency of screening.