Background Both obesity and underweight are associated with a higher risk of mortality in adulthood, but the association between mortality after arthroplasty and extreme ranges of body mass index (BMI) have not been evaluated beyond the first year. Questions/purposes The purpose of this study was to investigate the association between BMI and all-cause mortality after TKA and THA. Methods Data from two arthroplasty registries, the St Vincent's Melbourne Arthroplasty (SMART) Registry from Australia and the Kaiser Permanente Total Joint Replacement Registry (KPTJRR) from the United States, were used to identify patients aged $ 18 years undergoing elective TKAs and THAs between January 1, 2002, and December 31, 2013. Same-day bilateral THA and hemiarthroplasties were excluded. All-cause mortality was recorded from the day of surgery to the end of the study (December 31, 2013). Data capture was complete for the SMART Registry. No patients were lost to followup in the KPTJRR cohort and 2959 (5%) THAs and 5251 (5%) TKAs had missing data. Cox proportional hazard regression was used to estimate the all-cause mortality associated with six BMI categories: underweight (< 18.5 kg/ m 2 ), normal weight (18.5-24.9 kg/m 2 ), overweight (25.0-29.9 kg/m 2 ), obese class I (30.0-34.9 kg/m 2 ), obese class II (35.0-39.9 kg/m 2 ), and obese class III (> 40 kg/m 2 ). For TKA, the SMART cohort had a median followup of 5 years (range, 0-12 years) and the KPTJRR cohort had a median followup of 4 years (range, 0-12 years). For THA, the SMART cohort had a median followup of 5 years (range, 0-12 years) and the KPTJRR cohort had a median followup of 4 years (range, 0-12 years).
ASJC Scopus subject areas
- Orthopedics and Sports Medicine