Joeky Senders

51 Venous thromboembolism en intracranial hemorrhage ≥36%), platelet count (100-450/µm 3 , <100/µm 3 , vs. >450/µm 3 ), sodium (135-145 mEq/L, <135 mEq/L, vs. >145 mEq/L), white blood cell (WBC) count (≤12,000/µL vs. >12,000/µL), preoperative transfusion, preoperative systemic inflammatory response syndrome, admission two or more days before surgery, and anesthesia type (general versus no general anesthesia). Missing data Covariates with more than ten percent missing data or occurring in less than one percent of cases were excluded from multivariable analysis. Cases with missing data in one of the variables of the multivariable analysis were excluded from the analysis. A confirmatory analysis was performed for every multivariable model, in which missing data was coded as an additional group to verify if missing data affected the results. Outcomes VTE was defined as the occurrence of DVT or PE within 30 days after surgery. The occurrence of other major complications and reasons for readmission and reoperation were extracted by means of ICD-9 and CPT codes, to assess the relative contribution of VTE and ICH to morbidity, readmission, and reoperation. Based on a previously published definition, major complications were defined as either acute renal failure, cardiac arrest, death, failure towean fromventilator,myocardial infarction, reintubation, reoperation, stroke, VTE, sepsis, and surgical site infection. 38 ICH was defined as the occurrence of an ICH requiring surgical evacuation and extracted by means of CPT and ICD-9 codes. Reasons for reoperation including ICH were collected since 2012. Each primary thrombotic outcome (VTE, DVT, PE) was assessed for its occurrence during the initial hospital stay, after discharge, and within 30 days overall. ICH was assessed within 30 days overall. Statistical analysis Statistical analyses were conducted using R 3.3.3 (R Core Team, Auckland, New Zealand). Univariable analysis was performed using logistic regression. Potential predictors were selected for inclusion in the multivariable logistic regression analysis based on univariable analysis for each outcome. Only pre- and intraoperative factors were included in the multivariable analysis because inclusion of postoperative complications other than VTE or ICH would reduce the timeframe in which complications can be detected due to the limited 30-day collection period of NSQIP, thereby biasing the results of the model. Potential predictors were excluded from the final model if they demonstrated multicollinearity or had a relative low contribution to model fit.