Season and vitamin D status do not affect probability for surgical site infection after colorectal surgery

Background: Regardless of reports on the prevalence of hypovitaminosis D and seasonal effects in the general population and significant worsening of many outcomes there is a scarcity of studies focusing on surgical patients. We, therefore, designed a study to assess the association and difference in surgical-wound infections between patients having colorectal surgery in winter compared with patients having surgery in summer months. Methods: Patients were divided into winter and summer surgical procedures depending on their date of surgery. The relationship between seasons (and Vitamin D) and primary outcome of wound infections using multivariable logistic regression was assessed. Results: Out of 2919 patients, 241 (7.7 %) experience surgical site infection. The observed incidence of any surgical site infection postoperatively was 6.8 %, 9.9 %, 7.3 %, and 8.2 % for patients having surgery in spring, summer, fall, and winter, respectively. Furthermore, vitamin D concentration was not associated with incidence of surgical site infection (Odds Ratio (OR): 0.51(0.01, 27) for a one-unit increase in vitamin D concentration; p = 0.74). Conclusion: Our analysis suggests that perioperative vitamin D concentration is not associated with surgical site infections in colorectal surgical patients, likely because the outcomes are overwhelmingly determined by other baseline and surgical factors.