Length of Stay Among Infants with Neonatal Abstinence Syndrome and Risk of Hospital Readmission.

Objectives: To assess whether a shorter length of stay (LOS) is associated with a higher risk of readmission among newborns with neonatal abstinence syndrome (NAS) and examine the risk, causes, and characteristics associated with readmissions among newborns with NAS, using a longitudinally linked population-based database.

Methods: Our study sample included full-term singletons with NAS (n = 4,547) and without NAS (n = 327,836), born in Massachusetts during 2011-2017. We used log-binomial regression models to estimate the crude risk ratios (cRRs) and adjusted RRs with 95% confidence intervals (CI) of the association between LOS and readmissions, controlling for maternal age, race/ethnicity, education, marital status, insurance, method of delivery, birthweight, adequacy of prenatal care, smoking, and abnormal conditions of newborn.

Results: Compared with infants without NAS, infants with NAS had a non-significantly higher risk of readmission within 2-42 days (2.8% vs. 2.5%; p = 0.17) and a significantly higher risk of readmission within 43-182 days (2.7% vs. 1.8%; p < 0.001). The risk of readmission within 2-42 days was significantly higher among infants with NAS with a LOS of 0-6 days compared to a LOS of 14-20 days (reference group) (aRR: 2.1; 95% CI: 1.2-3.5). No significant differences in readmission rates between 43 and 182 days were observed across LOS categories.

Conclusions: Among infants with NAS, a LOS of 0-6 days was associated with a significantly higher risk of readmission within 2-42 days of discharge compared to a longer LOS.