A comparison of different methods for calculating overall risk scores from risk factors ascertained in a computerized...

Current obstetric risk-scoring systems depend upon simple addition of weighted or unweighted risk factors. In this study a population of 994 pregnant women (470 primiparae; 524 multiparae) has been examined in order to compare the use of weighted and unweighted risk scores, together with Bayes theorem, in estimating an overall risk score from the presence of individual risk factors. The findings have been related to fetal outcome in these pregnancies and expressed as receiver-operating characteristic (ROC) curves for different cutoff levels between normal and abnormal. In primiparae, the use of weighted risk factors, with or without Bayes theorem, was clearly superior to the use of unweighted factors. In multiparae there was only a marginal difference between the three approaches. The increasing use of computerised information system in antenatal care should make calculation of risk scores for every pregnant woman a practical option.