The "July Effect" scrutinized: A coarsened-exact match analysis of lumbar fusion outcomes during resident transition.

Objective: The aim of this study was to assess for a "July Effect" by comparing exact matched patients undergoing single-level spinal fusions in July or in the latter half of the academic year.

Methods: Data from 2338 patients who underwent single-level, posterior-only lumbar fusion at a single, multicenter university hospital system were retrospectively reviewed. The primary outcomes were 90-day unplanned hospital readmissions, Emergency Department (ED) evaluations, reoperations, non-home discharge, and all-cause mortality. The secondary outcomes assessed include length of hospital stay, main procedure time, procedure closure time, and total surgery duration. Outcomes of surgeries at the beginning (July) of the academic year were compared to those at the end of the year (April-June).

Results: Across 2338 patients, operative month had no effect on 90-day readmissions, ED visits, reoperations, mortality, or non-home discharge. Patients undergoing surgery in July vs April-June had a significantly longer mean procedure time, procedure closure time, and total duration of surgery, but not hospital length of stay. Among patients whom were exact matched, surgeries in July vs April-June had a significantly longer mean procedure closure time, but no significant differences in primary procedure time, total surgical duration, or length of stay in hospital.

Conclusions: Single level spinal fusion wound closure times are longer in July but postoperative morbidity and mortality are unchanged throughout the academic year. These findings support the current literature that teaching hospitals, and senior surgeons, provide adequate safeguards to ensure patient safety at all times.