In Reply We thank Dr Hall for his comments pertaining to our article, “Association of Preoperative Anemia with Postoperative Mortality in Neonates”1 and welcome the opportunity to respond to his concerns and the limitations highlighted in the accompanying Editorial.2 Our article reported an independent association between preoperative anemia (defined as hematocrit <40%) and in-hospital mortality in neonates undergoing noncardiac surgery in US hospitals. The accompanying Editorial2 as well as this Letter to the Editor raise the point that the lack of control for surgical complexity is a potential limitation and might confound the association between low hematocrit and high mortality. Even though we do agree that surgical complexity could be a confounding factor, we would like to emphasize that we did investigate the effect of surgical procedural category and complexity on mortality using the relative value unit. The relative value unit is based on the Centers for Medicare and Medicaid Services Resource Based Relative Value Scale and is a measure of operative complexity; it includes surgical diagnosis and surgical pathology. Relative value unit is used by the American College of Surgeons National Surgical Quality Improvement Program and has been shown in database analyses to independently predict postoperative morbidity following surgery.3- 5 Using parsimonious multivariable logistic regression analysis, we found anemia, American Society of Anesthesiologists class 3 to 5, body weight 2 kg or less, preoperative mechanical ventilation, and preoperative inotropic support to be independent predictors of mortality. With these variables entered in the model, it is no surprise then that surgical complexity does not provide additional discriminant value. With all due respect, no infant with these risk factors will be undergoing an elective inguinal hernia repair or any other minor surgical procedure. Consequently, our results accurately reflect an independent association between neonatal anemia and higher postoperative mortality when considering surgical complexity.
Goobie SM, Faraoni D, DiNardo JA. Association of Preoperative Anemia With Postoperative Mortality in Neonates—Reply. JAMA Pediatr. 2017;171(2):196-197. doi:10.1001/jamapediatrics.2016.2965