Comparison of outpatient and inpatient spine surgery patients with regards to obesity, comorbidities and readmission for infection.

Outpatient spine surgery is becoming popular because of its substantial economic advantages. We retrospectively studied 97 spine surgery outpatients and 578 inpatients who had proceeded through a common process of surgical venue selection. No differences (p > 0.05) were found in gender, race, obesity rate (46.9% versus [vs.] 42.9%), hypertension (9.7% vs. 8.8%), chronic obstructive pulmonary disease (11.8% vs. 13.5%), and history of stroke (1.9% vs. 2.5%). However, age was statistically different between inpatients (55 years) and outpatients (49 years) (p < 0.001). The prevalence of diabetes mellitus (19% vs. 10%), congestive heart disease (19.7% vs. 1.3%), coronary artery procedures (15.9% vs. 3.8%), and use of antidepressants (25.4% vs. 11.6%) was higher in the inpatient group (p < 0.05). There were more comorbidities in the inpatient cohort of each spine surgery type except for chronic obstructive pulmonary disease (COPD) and history of stroke in the outpatient cervical surgery group (p < 0.05). Among outpatients, only one patient (∼ 1%) had postoperative infection while among the inpatients, 16 patients had postoperative infections (2.8%) (p > 0.05). All seven patients readmitted due to infection were obese (body mass index ≥ 30). Obese patients in the inpatient cohort had higher chronic disease rates. Comorbidities are the main determinants of inpatient/outpatient selection. Postoperative infection was not a significant complication for appropriately selected patients for outpatient spine surgery. Despite increased hospital care and observation in the inpatient group, infection rates were not statistically different. Obesity seems to be a predictor of readmission with infection.