The Validity of Administrative BMI Data in Total Joint Arthroplasty.

Identifying BMI via administrative data is a useful way to evaluate outcomes in total joint arthroplasty (TJA) for varying degrees of obesity. The purpose of this study was to evaluate the concordance between BMI coding in administrative claims data and actual clinical BMI measurements in the medical record for patients undergoing TJA. Clinical BMI value was shown to be a significant determinant of whether ICD-9 codes were used to report the patient's obesity status (P<0.01). Although a higher clinical BMI strongly increased the likelihood of having either of the ICD-9 diagnosis codes used to identify obesity status, only the accuracy of the V85 code increased with increasing levels of BMI.