Objective:

To investigate the role of seasonality on postoperative complications following spinal surgery.

Methods:

Data were obtained from the American College of Surgeons National Surgical Quality Improvement Program database from 2011-2018. Current Procedural Terminology codes were used to identify the following procedures: posterior cervical decompression and fusion, cervical laminoplasty, posterior lumbar fusion, lumbar laminectomy, and spinal deformity surgery. The database was queried for deep vein thrombosis (DVT), pulmonary embolism (PE), pneumonia, sepsis, septic shock, Clostridium difficile infection, stroke, cardiac arrest, myocardial infarction, urinary tract infection (UTI), and Early Unplanned Hospital Readmission (readmission). Warm season was defined as April-September while cold season was defined as October-March. Statistical analysis included computing overall complication rates and comparison between seasons using univariate analysis and multivariable logistic regression.

Results:

208,291 individuals underwent spinal surgery from 2011-2018. There was a statistically significant increase in UTI (OR 1.16, 95% CI: 1.07-1.26, p=0.0002) and readmission (OR 1.06, 95% CI 1.02-1.11, p=0.007) in the warm season compared to the cold season. An investigation into the July Effect revealed increases to DVT (OR 1.24, 95% CI 1.03-1.48, p=0.020) and thromboembolic events (TE; OR 1.17, 95% CI 1.01-1.35, p=0.032) in July – September compared to the preceding three months.

Conclusions:

The results showed a higher incidence of UTI and readmission among spine surgery patients in the warm season and a higher incidence of DVT and TE from July-September. In both cases, the effect of seasonality is statistically significant, but the absolute difference is small and may not suggest policy changes.