Adult spinal deformity surgery: the effect of surgical start time on patient outcomes and cost of care.

PURPOSE: There are reports investigating the effect of surgical start time (SST) on outcomes, length of stay (LOS) and cost in various surgical disciplines. However, this has not been studied in spine deformity surgery to date. This study compares outcomes for patients undergoing spinal deformity surgery based on SST.

METHODS: Patients at a single academic institution from 2008 to 2016 undergoing elective spinal deformity surgery (defined as fusing ≥ 7 segments) were divided by SST before or after 2 PM. Co-primary outcomes were LOS and direct costs. Secondary outcomes included delayed extubation, ICU stay, complications, reoperation, non-home discharge, and readmission rates.

RESULTS: There were 373 surgeries starting before 2 PM and 79 after 2 PM. The cohorts had similar demographics including age, sex, comorbidity burden, and levels fused. The late SST cohort had shorter operation durations (p = 0.0007). Multivariable linear regression showed no differences in LOS (estimate 0.4 days, CI - 1.2 to 2.0, p = 0.64) or direct cost (estimate $3652, 95% CI - $1449 to $8755, p = 0.16). Multivariable logistic regression revealed the late SST cohort was more likely to have delayed extubation (OR 2.6, 95% CI 1.4-4.9, p = 0.004) and non-home discharge (OR 2.2, 95% CI 1.1-4.2, p = 0.03). All other secondary outcomes were non-significant.

CONCLUSION: Patients undergoing spinal deformity surgery before and after 2 PM have similar LOS and cost of care. However, the late SST cohort had increased likelihood of delayed extubation and non-home discharges, which increase cost in bundled payment models. These findings can be utilized in OR scheduling to optimize outcomes and minimize cost.