Objective: To ascertain whether the TDx-FLM assay is a better predictor of neonatal respiratory distress syndrome (RDS) than the lecithin-sphingomyelin ratio (L/S) and phosphatidylglycerol (PG).
Methods: Amniotic fluid samples of 140 women requiring assessment of fetal lung maturity and delivering within 72 hours of amniocentesis were analyzed by the three methods. The accuracy in predicting RDS was assessed by conventional statistical techniques.
Results: The TDx-FLM test had a better sensitivity (89.6 versus 48.2%; relative risk [RR] 3.9, 95% confidence interval [CI] 1.35-11.23, P = .001) and negative predictive value (96.4 versus 86.8%; RR 0.36, 95% CI 0.12-1.04, P = .02) than the L/S. However, the L/S had a better specificity (89.1 versus 73.8%; RR 0.64, 95% CI 0.49-0.82, P = .005) than the TDx-FLM assay. The PG test had a predictive ability similar to that of the TDx-FLM assay. However, there was no significant difference in the overall accuracy of the three tests, and the areas under the receiver-operating characteristic curves for the L/S and TDx-FLM (0.80 and 0.87) were similar.
Conclusions: The TDx-FLM assay performs similarly to the L/S and PG tests in the prediction of RDS and is quantitative, rapid, and reproducible.