Objective: Several groups, including ours, have developed probabilistic models that incorporate both the surfactant-to-albumin ratio (TDx-FLM II) and gestational age to more accurately predict the risk of neonatal respiratory distress syndrome (RDS) and eliminate the current categorical "immature"/"indeterminate"/"mature" interpretation. We validate our model using a separate data set, with the goal of providing the clinician with a risk score.
Methods: The medical records of all women who had TDx-FLM II testing performed at Brigham and Women's Hospital between January 1, 2003, and December 31, 2005, were reviewed to gather a population upon which to validate our previous logistic regression model. Receiver operating characteristic curve and Hosmer-Lemeshow analysis was conducted to determine the performance of our model and another model in this new population.
Results: A total of 233 mother-neonate pairs (21 RDS, 212 non-RDS) met criteria for analysis. The receiver operating characteristic analysis illustrated that our previous formula was a strong predictor of the risk of RDS with an area under the curve of 0.902 (95% confidence interval 0.849-0.955). In addition, using the Hosmer-Lemeshow analysis, our formula produced an excellent overall fit (P=.95), whereas another published model was a poor fit to our data (P=.002).
Conclusion: Our previously derived logistic regression model formula incorporating TDx-FLM II results and gestational age to predict risk of neonatal respiratory distress syndrome was robust and stable over time in an independent data set. The results suggest that the equation can be implemented clinically to assist physicians and patients and used by other institutions after their own internal validation.
Level of evidence: III.