Causes and risk factors for postoperative fever in spine surgery patients.

Postoperative fever is a common dilemma faced by neurosurgeons. To study this problem, we prospectively collected patients who developed fever after spine surgery during the academic year 2007-2008 for whom the internist's consultation was requested. Eighty-five (85) patients were identified, of which 17 had an identifiable infectious cause for their febrile reaction (20%) - fever was attributed to urinary tract infection in 8 cases, pneumonia in 5 cases, wound infection in 3 cases (all lumbar), and cholecystitis in 1 case. The remaining 68 patients (80%) had no definitive diagnosis and fever was attributed to a peripheral venous line which, in this case, was replaced or discontinued. In 32 (37.6%) of the patients, the fever developed on postoperative day (POD) 2 or later. There was no statistically significant relationship between day of fever appearance and whether the fever was due to definite infection (P = 0.737). Comparing the basic group with another group of 456 spine surgery patients from 2006-2007 who might or might not have developed fever postoperatively using ANOVA, we found a significant difference in age (P = 0.011) and a very significant difference in hemoglobin level (P = 0.000) and HbA1c level (P = 0.000), but not in body mass index (BMI) (P = 0.289). Thus, most of the postoperative fever cases after spine surgery have no identifiable infectious focus and develop mainly in older patients with anemia and inadequately controlled HbA1c. A meticulous investigation of the source of fever including laboratory and radiological studies remains essential. Early mobilization is recommended for individuals undergoing lower spine surgery in order to decrease bacterial contamination from the gluteal cleavage.