The sensitivity and specificity of a preterm risk score for various patient populations

Scoring systems to identify women at high risk for delivering low birthweight infants are used to place high-risk women into special prenatal clinics. The March of Dimes Birth Defects Foundation scoring system was evaluated to determine its sensitivity, specificity, and positive predictive value at each cutoff point between 0 and 20 for various patient profiles when conducted before 29 weeks' gestation. In the present study, 9014 singleton births in 1985 and 1986 from nine Florida county health units were reviewed. Scores of 1, 5, 10, and 20 provided a sensitivity of 0.96, 0.66, 0.26, and 0.02, a specificity of 0.05, 0.44, 0.86, and 0.99, and a positive predictive power of 8.7, 10.1, 15.9, and 21.1, respectively. Differences in the sensitivity and specificity of the scores existed among subsets in the study population classified by gravida, age, race, and urban or rural county. Overall, the applicability was restricted, and the positive predictive value appeared best if a cutoff point of 15 was used, which represented the upper 5th percentile of the population. It was concluded that a greater emphasis was needed to designate scores for specific subpopulations and to give more consideration to psychosocial factors associated with having low birthweight infants.