Trends in racial/ethnic disparities in postpartum hospital readmissions in California from 1997 to 2018

BACKGROUND

Postpartum readmission is an important indicator of postpartum morbidity. The likelihood of postpartum readmission is highest for Black individuals. However, it is unclear whether the likelihood of postpartum readmission has changed over time according to race/ethnicity. Little is also known about the factors that contribute to these trends.

OBJECTIVE

This study aimed to: (1) examine trends in postpartum readmission by race/ethnicity, (2) examine if prenatal or clinical factors explain the trends, and (3) investigate if racial/ethnic disparities changed over time.

STUDY DESIGN

We examined trends in postpartum readmission, defined as hospitalization within 42 days after birth hospitalization discharge, using live birth and fetal death certificates linked to delivery discharge records from 10,711,289 births in California from 1997 to 2018. We used multivariable logistic regression models that included year and year-squared (to allow for nonlinear trends), overall and stratified by race/ethnicity, to estimate the annual change in postpartum readmission during the study period, represented by odds ratios and 95% confidence intervals. We then adjusted models for prenatal (eg, patient demographics) and clinical (eg, gestational age, mode of birth) factors. To determine whether racial/ethnic disparities changed over time, we calculated risk ratios for 1997 and 2018 by comparing the predicted probabilities from the race-specific, unadjusted logistic regression models.

RESULTS

The overall incidence of postpartum readmission was 10 per 1000 births (17.4/1000 births for non-Hispanic Black, 10/1000 for non-Hispanic White, 7.9/1000 for non-Hispanic Asian/Pacific Islander, and 9.6/1000 for Hispanic individuals). Odds of readmission increased for all groups during the study period; the increase was greatest for Black individuals (42% vs 21%–29% for the other groups). After adjustment for prenatal and clinical factors, the increase in odds was similar for Black and White individuals (12%). The disparity in postpartum readmission rates relative to White individuals increased for Black individuals (risk ratio, 1.68 in 1997 and 1.90 in 2018) and more modestly for Hispanic individuals (risk ratio, 1.02 in 1997 and 1.05 in 2018) during the study period. Asian/Pacific Islander individuals continued to have lower risk than White individuals during the study period (risk ratio, 0.87 in 1997 and 0.82 in 2018).

CONCLUSION

The rate of postpartum readmissions increased from 1997 to 2018 in California across all racial/ethnic groups, with the greatest increase observed for Black individuals. Racial/ethnic differences in the trend were more modest after adjustment for prenatal and clinical factors. It is important to find ways to prevent further increases in postpartum readmission, especially among groups at highest risk.