A Reduction in Body Mass Index From ≥ 40 to < 40 Lowers Emergency Department Visits, but May Increase All-Cause Readmissions After Primary Total Hip Arthroplasty: Conflicting 90-Day Outcomes at a Single Institution.

BACKGROUND

The American Association of Hip and Knee Surgeons tasked a 2013 workgroup to provide obesity-related recommendations in total joint arthroplasty. Morbidly obese patients (body mass index (BMI) ≥ 40) seeking hip arthroplasty were determined to be at increased perioperative risk, and surgeons were recommended to encourage these patients to reduce their BMI <40 presurgery. We report the effect of instituting a 2014 BMI <40 threshold on our primary total hip arthroplasties (THAs).

METHODS

We queried our institutional database to select all primary THAs from January 2010 to May 2020. There were 1,383 THAs that were pre-2014 and 3,273 THAs that were post-2014. The 90-day emergency department (ED) visits, readmissions, and returns to operating room (OR) were identified. Patients were propensity score weight-matched according to comorbidities, age, initial surgical consultation (consult) BMI, and sex. We conducted 3 comparisons: A) pre-2014 patients who had a consult and surgical BMI ≥40 against post-2014 patients who had a consult BMI ≥40 and surgical BMI <40; B) pre-2014 patients against post-2014 patients who had a consult and surgical BMI <40; and C) post-2014 patients who had a consult BMI ≥40 and surgical BMI <40 against post-2014 patients who had a consult BMI ≥40 and surgical BMI ≥40.

RESULTS

Post-2014 patients who had a consult BMI ≥ 40 and surgical BMI <40 had less ED visits (7.6 versus 14.1%, P = .0007), but similar readmissions (11.9 versus 6.3%, P = .22) and returns to OR (5.4 versus 1.6%, P = .09) compared to pre-2014 patients who had a consult BMI and surgical BMI ≥ 40. Post-2014 BMI <40 had less readmissions (5.9 versus 9.3%, P < .0001), and similar all-cause returns to OR and ED visits than patients pre-2014. Post-2014 patients who had a consult and surgical BMI ≥ 40 had lower readmissions (12.5 versus 12.8%, P = .05), and similar ED visits and returns to OR than consult BMI ≥ 40 and surgical BMI <40.

CONCLUSION

Patient optimization prior to total joint arthroplasty is critical. However, the BMI optimization that mitigates risk in primary total knee arthroplasty may not apply to primary THA. We observed a paradoxical increased readmission rate for patients who reduced their BMI before THA.

LEVEL OF EVIDENCE

III.