Comment on the Positive Predictive Value

Abstract

I enjoyed reading this informative and well structured article. Everyone involved in neonatal screening-in hospital and clinical practice and in the laboratory-would be well advised to have this review article and its practical tables ready to hand. I do not think, however, that the positive predictive value reported by the authors on page 16 for the immuno chemical 17-OH progesterone screening (3%), can be deduced from the authors' data on the specificity (adrenogenital syndrome [AGS] 99.39%, page 16) and the confirmed cases (AGS: 216) or the incidence (1:12 771) in Table 1 on page 14; and neither can it be concluded from the cited bibliographical source (2). The positive predictive value for AGS screening can therefore be assumed to be in the region of 1.3%, which means that about 80 (rather than 30) neonates would have to be examined in order to identify one baby with the syndrome.