A Comprehensive Analysis of the Costs of Severe Maternal Morbidity

INTRODUCTION: The objectives of this study were to include readmissions and physician costs in the estimates of total costs of severe maternal morbidity (SMM), to consider the effect of SMM on maternal length of stay (LOS), and to examine these for the more restricted definition of SMM that excludes transfusion-only cases. METHODS: California linked birth certificate-patient discharge data for 2009-2011 (N=1,262,862) with complete costs and LOS were used in a secondary data analysis. Cost-to-charge ratios were used to estimate costs from charges, adjusting for inflation. Physician payments were estimated from mean payments for specific diagnosis related groups. Generalized linear models estimated the association between SMM and costs and LOS. RESULTS: Excluding readmissions and physician costs, SMM was associated with a 60% increase in hospital costs (marginal effect (ME) $3,550) and 33% increase in LOS (ME 0.9 days). These increased to 70% (ME $5,806) and 46% (ME 1.3 days) when physican costs and readmissions were included. The effects of SMM were roughly half as large for patients who only required a blood transfusion (49%, ME $4,056 and 31%, ME 0.9 days) as for patients who had another indicator for SMM (93%, ME $7,664 and 62%, ME 1.7 days). CONCLUSIONS: Postpartum hospital readmissions and physician costs are important and previously unreported contributors to the costs of SMM. Excess costs and LOS associated with SMM vary considerably by indication. Cost effects were larger than the LOS effects, indicating that SMM increases treatment intensity beyond increasing LOS, and reducing SMM may have broader health and cost benefits than previously understood.