What factors contribute to hospital variation in obstetric transfusion rates?

Abstract

Background and objectives: To explore variation in red blood cell transfusion rates between hospitals, and the extent to which this can be explained. A secondary objective was to assess whether hospital transfusion rates are associated with maternal morbidity.

Materials and methods: Linked hospital discharge and birth data were used to identify births (n = 279 145) in hospitals with at least 10 deliveries per annum between 2008 and 2010 in New South Wales, Australia. To investigate transfusion rates, a series of random-effects multilevel logistic regression models were fitted, progressively adjusting for maternal, obstetric and hospital factors. Correlations between hospital transfusion and maternal, neonatal morbidity and readmission rates were assessed.

Results: Overall, the transfusion rate was 1.4% (hospital range 0.6-2.9) across 89 hospitals. Adjusting for maternal casemix reduced the variation between hospitals by 26%. Adjustment for obstetric interventions further reduced variation by 8% and a further 39% after adjustment for hospital type (range 1.1-2.0%). At a hospital level, high transfusion rates were moderately correlated with maternal morbidity (0.59, P = 0.01), but not with low Apgar scores (0.39, P = 0.08), or readmission rates (0.18, P = 0.29).

Conclusion: Both casemix and practice differences contributed to the variation in transfusion rates between hospitals. The relationship between outcomes and transfusion rates was variable; however, low transfusion rates were not associated with worse outcomes.

Keywords: clinical practice variation; obstetric delivery; red blood cell trans-fusion.

Figure 1

Variation in hospital transfusion rates for red blood cell transfusion in the birth admission, NSW, 2008–2010^a. ^aDots represent hospital red blood cells transfusion rates, with 95% confidence intervals, and the horizontal line the average rate.

Figure 2

Adjusted rates of maternal and neonatal morbidity and transfusion, NSW, 2008–2010. *Dots represent hospital transfusion and morbidity rates. In each graph, the bold horizontal line is the average morbidity rate, and the bold vertical line is the average transfusion rate.