Impact of Length of Stay on Readmission in Hospitalized Patients.

Background Readmission and length of stay (LOS) are two hospital-level metrics commonly used to assess the performance of hospitalist groups. Healthcare systems implement strategies aimed at reducing both. It is possible that tactics aimed at improving one measure in individual patients may adversely impact the other.  Objective We sought to analyze the impact of length of stay on readmission risk in an inpatient general medical population to assess whether patients with a lower length of stays were readmitted more frequently to the hospital. Methods We performed a retrospective analysis of inpatient adult patients admitted to our institution between January 2016 and December 2019. We recorded demographic variables and the outcomes of LOS and 30-day readmission. We excluded patients who expired, left against medical advice, or were transferred to other hospitals. We performed both univariate and multivariate analyses. Results There were 91,723 patients included in the study of which 10,598 (11.6%) were readmitted. The geometric LOS for all patients was 5.37 days and was higher in readmitted patients (6.87 vs 5.18 days, respectively, p < 0.001). Patients with higher readmission rates were older, had a higher proportion of male gender, African-American ethnicity, and were more likely to have Medicare or Medicaid payors. After performing a multivariate regression analysis, we found that a high LOS was associated with a higher likelihood of readmission (P < 0.001). Conclusion Contrary to our initial hypothesis, we found that general medical patients with a higher LOS had a higher likelihood of being readmitted to the hospital after adjusting for other variables. It is possible that factors not captured in the current dataset may help explain both the increase in LOS and readmission risk.