Risk-adjusted intraventricular hemorrhage rates in very premature infants: towards quality assurance between neonatal units

Abstract

Background: The incidence of intraventricular hemorrhage (IVH) in very low birth weight infants can be used as an index of the quality of care in neonatal intensive care units as long as it is adjusted to reflect the infants' risk profiles on admission to the unit, which may vary systematically from one institution to another. Adjustment for gestational, birth-related, and neonatological risk factors enables a fair comparison of IVH rates across neonatal intensive care units.

Methods: Data on 1782 neonates born at less than 32 weeks of gestation or weighing less than 1500 g at birth were retrieved from the 26 744 anonymous data sets collected in the Peri- and Neonatal Survey of the German state of Saxony in the years 2001-2005. An analysis of 30 putative risk factors with stepwise logistic regression analysis enabled the construction of a specific risk predictor for severe (grade 3-4) IVH. Risk-adjusted institutional incidence rates were then calculated.

Results: Five independent risk factors (low gestational age, low Apgar scores at 1 min, early infection, absence of pathological Doppler findings during pregnancy, and the use of tocolytic agents) were found to be relevant to the prediction of IVH. A risk predictor incorporating them was found to have a correct prediction rate (ROC(AUC) value) of 87.7%. The crude incidence of severe IVH in different institutions ranged from 1.92% to 15.02% (mean, 8.55%); after adjustment, the range was 5.14% to 11.58%. When the institutions studied were ranked in order of their incidence of IVH before and after adjustment for risk factors, individual institutions rose or fell by as many as 4 places in the ranking because of the adjustment.

Conclusion: These findings reveal the importance of adjusting the incidence of IVH in very low birth weight infants by the patients' risk profiles to enable valid comparisons between institutions for the purpose of quality surveillance.

Figures

Figure

Incidence rates of severe intraventricular hemorrhage (IVH) (grade 3–4) before (▼) and after (■) risk adjustment together with predicted values (▲) based on the multivariate predictor, calculated according to the obstetric risk profile