Preoperative hemoglobin thresholds for increased risk of “medical” complications in fast‐track total hip and knee arthroplasty, a secondary analysis of a machine‐learning algorithm

Abstract

AbstractBackgroundThere is increasing evidence that gender‐specific hemoglobin thresholds may not be ideal in the surgical population. Thus, preoperative anemia defined as a hemoglobin of <13.0 g/dL is a well‐established risk factor in elective surgery. However, few studies have investigated the specific influence of preoperative hemoglobin within a machine‐learning model using data from an optimized fast‐track surgical setup.Study Design and MethodsA secondary analysis on the specific influence of preoperative hemoglobin level on a machine‐learning model developed for identifying patients at increased risk of a length of stay (LOS) of >4 day or readmissions due to medical complications in fast‐track total hip and knee arthroplasty within a well‐defined fast‐track protocol. To evaluate the effect of hemoglobin on the model we calculated SHaply Additive Explanation (SHAP) values for the 3913 patients from our previous test‐dataset and stratified by gender and total hip and knee arthroplasty, respectively.ResultsThe study period ran from January 2017 to August 2017. Median LOS was 1 day and mean preoperative Hb was 15.5 g/dL (SD:1.5), lower in women (14.9 vs. 16.2 g/dL) and with 30.5% of women versus 12.0% of men having a Hb of <13.0 g/dL. There was a steep increase in SHAP value with a preoperative Hb < 14.8 g/dL, and irrespective of gender age and procedure type.DiscussionA machine‐learning model found a hemoglobin threshold of <14.8 g/dL for increased risk of impaired recovery, regardless of gender or age, supporting reevaluation of preoperative anemia thresholds in the elective surgical setting.