Prolonged Length of Stay and Risk of Unplanned 30-Day Readmission After Elective Spine Surgery: Propensity Score-Matched Analysis of 33,840 Patients.

Abstract

Retrospective database study. To assess the association between prolonged length of hospital stay (pLOS) (≥4 d) and unplanned readmission in patients undergoing elective spine surgery by controlling the clinical and statistical confounders. pLOS has previously been cited as a risk factor for unplanned hospital readmission. This potentially modifiable risk factor has not been distinguished as an independent risk factor in a large-scale, multi-institutional, risk-adjusted study. Data were collected from the American College of Surgeons National Surgical Quality Improvement Program database. A retrospective propensity score-matched analysis was used to reduce baseline differences between the cohorts. Univariate and multivariate analyses were performed to assess the degree of association between pLOS and unplanned readmission. From the 99,575 patients that fit the inclusion criteria, propensity score matching yielded 16,920 well-matched pairs (mean standard propensity score difference = 0.017). The overall 30-day unplanned readmission rate of these 33,840 patients was 5.5%. The mean length of stay was 2.0 ± 0.9 days and 6.0 ± 4.5 days (P ≤ 0.001) for the control and pLOS groups, respectively. In our univariate analysis, pLOS was associated with postoperative complications, especially medical complications (22.7% vs. 8.3%, P < 0.001). Multivariate analysis of the propensity score-matched population, which adjusted identified confounders (P < 0.02 and ≥10 occurrences), showed pLOS was associated with an increased risk of 30-day unplanned readmission (odds ratio [OR] 1.423, 95% confidence interval [CI] 1.290-1.570, P < 0.001). Patients who undergo elective spine procedures who have any-cause pLOS (≥4 d) are at greater risk of having unplanned 30-day readmission compared with patients with shorter hospital stays. 4.