Accuracy of salivary estriol testing compared to traditional risk factor assessment in predicting preterm birth

Objective: The objective was to compare the predictive accuracy (percentage of correct vs incorrect predictions) of salivary estriol levels (SalEst; Biex, Inc, Dublin, Calif) with that of the modified Creasy score for predicting preterm labor followed by preterm delivery. Study Design: A triple-blinded prospective trial was conducted at 8 US centers. Results: Among 601 evaluable patients, serial salivary estriol testing correctly predicted the appropriate outcome 91% of the time and the Creasy scoring method correctly predicted the appropriate outcome 75% of the time (McNemar test P < .001). Among subjects with Creasy scores ≥10 (high-risk group, n = 152), use of salivary estriol testing correctly predicted the end point 87% of the time, compared with only 7.2% correctly predicted by modified Creasy scoring (McNemar test P < .001). Conclusion: Salivary estriol assessment was more accurate in predicting outcome than was modified Creasy scoring. (Am J Obstet Gynecol 1999;180:S214-8)