The effect of July admission on inpatient morbidity and mortality after adult spinal deformity surgery.

Background: Some studies have suggested patients who undergo surgery in July have worse outcomes compared to patients treated during other months. The purpose of this study is to compare inpatient morbidity and mortality among patients who underwent adult spinal deformity (ASD) surgery in July with those who underwent surgery in other months.

Methods: Admission data for patients who underwent ASD surgery were extracted from the Nationwide Inpatient Sample for the years 2002 to 2011. Only adult patients (over 21 years of age) and elective admissions to teaching hospitals were included. A multivariable regression analysis was performed to examine the independent effect of July admissions on overall complications, major complications, and inpatient mortality.

Results: A total of 27,794 patients were identified, with 2,023 (7.8%) admitted in July and 25,771 (92.2%) in other months. Overall complication rates in July (43.1%) were not different from rates in other months (44.9%, p=0.468). Similarly, major complication rates were similar; 12.9% in July and 12.4% in other months (p=0.764). Mortality was not different between groups (p=0.807). After multivariable analysis, July admissions were not found to increase the odds of developing any complication (OR 0.94; 95% CI, 0.77 - 1.12; p=0.403), major complications (OR 1.04; 95% CI, 0.76 - 1.41; p=0.788) or inpatient mortality (OR 1.35; 95% CI, 0.31 - 5.84; p=0.684).

Conclusion: In this study of a nationwide database, patients who underwent ASD surgery in July did not have increased odds of developing a complication or inpatient mortality compared to patients admitted in other months.