The Response

THE authors of the accompanying article by De la Garza Ramos et al. present a retrospective, singlecenter study from an urban teaching hospital with patients undergoing spine surgery for metastatic disease.1 The primary outcome measure was 90-day mortality and secondary outcome measures were 12-month mortality and wound infection. The biomarkers assessed were the patient's body mass index (BMI), body weight, Prognostic the Nutritional Risk Index (NRI). For statistical analysis, the authors used a c-statistic of >= 0.70 to define a clinipredict mortality as well as regression analyses for each biomarker.