Weighing in: Effect of BMI on Postoperative Fever and Complications in Patients Undergoing Three Distinct Surgeries

Abstract

BackgroundCurrent trends estimate a 33% increase in obesity and 130% increase in severe obesity by the year 2030. It is unclear what the effect of obesity is on postoperative fevers, postoperative complications, and diagnostic workup rates.MethodsWe evaluated 5,330 patients undergoing knee arthroplasty, colectomy, or craniectomy from October 2009 to December 2014 at NorthShore University HealthSystem, in Illinois. Clinical data were extracted from the Enterprise Data Warehouse, including diagnostic testing and complications. Complications were also verified by physician chart review. Χ2 and Mann–Whitney U tests were used to analyze categorical and continuous variables.ResultsObesity (BMI ≥ 35) was present in 1081 (23.4%) of knee arthroplasty, 38 (16.9%) of colectomy and 55 (12.6%) of craniectomy patients. There was no increase in complications by BMI in each individual surgery except for increased 30-day readmissions in craniectomy patients with BMI ≥ 35 (P = 0.032). Collectively, there was no difference in the relationship between BMI and rate of post-op complications (Table 1). However, patients with BMI ≥ 35 experienced more fevers (P = 0.002), underwent additional workup (0.011), and had higher workup costs (P < 0.001).ConclusionPatients with BMI ≥ 35 had more fevers, more workups and higher cost, but not higher complication rates during the index hospitalization after surgery. Awareness of the predisposition towards post-op fever in obese patients in the absence of complication may prevent costly and unnecessary testing. More work is still needed to understand the effect of obesity on more distant complication rates.Table 1: Post-Surgical Characteristics, Stratified by BMIBMI < 35 kg/m2, N = 4,156BMI ≥ 35 kg/m2, N = 1,174 P-valueSurgery Knee arthroplasty3533 (85%)1081 (92.1%)<0.001 Colectomy187 (4.5%)38 (3.2%) Craniectomy436 (10.5%)55 (4.7%)Fever ≥100.4696 (16.7%)242 (20.6%)0.002Fever ≥ 101329 (7.9%)125 (10.6%)0.003Any Work-Up2409 (58%)729 (62.1%)0.011Any in-hospital complication341 (8.2%)86 (7.3%)0.327Median work-up costs, dollars (IQR)51,038 (46656–57436)52,697 (48644–58517)<0.001Median length of stay, days (IQR)3.0 (2.0–3.0)3 (2.0–3.0)0.52430 days Readmission184 (4.4%)53 (4.5%)0.898Death w/in 30 days12 (0.3%)3 (0.3%)0.754Disclosures All authors: No reported disclosures.