928: Case mix and the utility of postpartum readmission rates as a marker of quality in obstetrics

Abstract

Postpartum readmission rates have been discussed as a potential quality metric in obstetrics. The objective of this project was to determine the relative effects of case mix on a hospital's postpartum readmission rate. This retrospective cohort study was conducted using the State Inpatient Databases from CA, FL, and NY between 2004 and 2013. Women who delivered at hospitals with >100 deliveries/year were included. We compared patient and hospital characteristics among hospitals with low and high readmission rates using chi-squared tests. Risk-adjusted 30-day readmission rates were calculated for patient, delivery, and hospital characteristics to understand how case mix and hospital factors affect a patient’s risk for readmission using fixed and random effects models. The average 30-day readmission rates were 1.15%, 1.57%, and 1.42% in California, Florida, and New York from the 3,164,429, 1,890,802, and 2,257,360 deliveries included from each state, respectively. There were notable differences in the distributions of patients cared for at high readmission hospitals compared to low readmission hospitals. Patients were more likely to identify as white, have private insurance and higher incomes, and have fewer comorbidities at low readmission hospitals in all states. These characteristics were associated with a lower risk of readmission, as shown by the adjusted rates in Table 1. The patient characteristics with the highest risk-adjusted readmission rates varied by state, but included hypertension (range 2.14-3.04%), obesity (1.78-2.94%), preterm labor/delivery (2.50-2.60%), and seizure disorder (1.78-3.35%). Delivery complications were also associated with increased risk-adjusted readmission rates (Table 2), but overall occurred rarely. In comparison, hospital characteristics did not have a profound impact on readmission risk compared to the patient characteristics (Table 2). Postpartum readmissions are an overall uncommon event that are affected by unmodifiable factors, such as demographics, socioeconomic status, and underlying comorbidities. The use of unadjusted readmission rates as a quality metric in obstetrics would disproportionately affect hospitals caring for higher risk, sicker patients.View Large Image Figure ViewerDownload Hi-res image Download (PPT)