Body Mass Index and Modified Glasgow Prognostic Score are Useful Predictors of Surgical Site Infection after Spinal Instrumentation Surgery: A Consecutive Series.

Abstract

STUDY DESIGN\nRetrospective observational study.\n\n\nOBJECTIVE\nTo analyze a large consecutive cohort of patients who had undergone spinal instrumentation surgery, to characterize a patient population with surgical site infections (SSI), and to identify preoperative risk factors associated with SSI.\n\n\nSUMMARY OF BACKGROUND DATA\nMalnutrition is a risk factor for SSI in many health conditions; however, the evidence connecting preoperative malnutrition with SSI in spinal instrumentation surgery is limited because of the small number of retrospective studies. While the modified Glasgow prognostic score (mGPS), C-Reactive protein (CRP)-albumin ratio (CAR), controlling nutritional status index (CONUT), prognostic nutritional index (PNI), platelet-lymphocyte ratio (PLR), and neutrophil-lymphocyte ratio (NLR) are established methods for evaluating nutritious status, little has been reported on the predictive value of these indicators with respect to postoperative spinal infection.\n\n\nMETHODS\nWe retrospectively investigated 384 patients who underwent spinal instrumentation surgery. We evaluated the significance of risk factors, including mGPS, CAR, CONUT, PNI, PLR, and NLR. We then performed stepwise logistic regression analysis to analyze the concurrent effects of various factors on the prevalence of SSI.\n\n\nRESULTS\nOf the 384 patients analyzed, 14 were diagnosed with SSIs. Univariate analysis showed that preoperative BMI, lymphocyte count, albumin, erythrocyte sedimentation rate, CRP, CONUT, mGPS, CAR, and PNI were risk factors for SSI. Stepwise logistic regression analysis revealed that higher mGPS and lower BMI before surgery were independent risk factors for SSI. A receiver operating characteristic curve showed that the cuff-off values of mGPS and BMI were 1 and 20.39, respectively.\n\n\nCONCLUSIONS\nThe risk factors for SSI after spinal instrumentation surgery were mGPS ≧ 1 and BMI ≦ 20.39\u200akg/m. These findings could help to identify patients at higher risk of SSI after spinal instrumentation surgery.\n\n\nLEVEL OF EVIDENCE\n4.