Increased Body Mass Index Is Associated With Increased Cost for Primary Total Hip Arthroplasty Irrespective of Complications or Readmissions.

BACKGROUND

Surgeons participating in alternative payment models may encounter financial disincentives in caring for patients whose care requires higher costs for the treatment facility. While smaller studies have shown a positive relationship between body mass index (BMI) and cost in total hip arthroplasty (THA), this question has yet to be examined using data in a nationally representative dataset. We sought to leverage a national dataset to assess the relationship between BMI and cost in THA.

METHODS

We queried a health care dataset from 2016 to 2022 to identify primary THAs using Current Procedural Terminology and International Classification of Disease-Procedure Coding System codes (27130, 0SR90xx, and 0SRB0xx) with a corresponding osteoarthritis diagnosis (International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM): M16). Patient demographics, characteristics, and cost variables were extracted directly from the dataset. Cost was defined by supplies, labor, and equipment and assessed over a 90-day period starting with the index surgical encounter. A multivariate generalized linear model estimated costs across eight BMI categories (World Health Organization BMI categories, with BMI > 40 patients grouped into BMI 40 to 45, BMI 45 to 50, and BMI > 50). A linear regression model assessed the effect of BMI on costs. Both models controlled for age, sex, payer, race, the Elixhauser comorbidity index, and ethnicity.

RESULTS

This study examined 10,366 primary THAs completed from 2016 to 2022. The mean BMI was 30.0 (standard error [SE] ± 0.1), the mean index cost was $14,632 (SE 52.9), and the mean 90-day cost was $16,527 (SE 145.4). Index and 90-day costs were lowest in the BMI 25 to 30 cohort ($14,344 and $15,865) and highest for the BMI >50 cohort ($17,503 and $28,281), respectively. On multivariate analyses, index and 90-day cost increased by $23 and $69, respectively, for every one-point increase in BMI (P < 0.001).

CONCLUSIONS

Results from this nationally representative dataset demonstrate that increasing BMI is associated with increased index and 90-day costs for THA. This information may be useful to stakeholders in the development of alternative payment models.