The impact of body mass index on patient reported outcome measures (PROMs) and complications following primary hip arthroplasty.

Influence of BMI upon patient outcomes and complications following THA was examined across a national cohort of patients. Outcomes were compared by BMI groups (19.0-29.9kg/m(2) [reference], 30.0-34.9kg/m(2) [obese class I], 35.0kg/m(2)+ [obese class II/III]), adjusted for case-mix differences. Obese class I patients had a significantly smaller improvement in OHS (18.9 versus 20.5, P<0.001) and a greater risk of wound complications (odds ratio [OR]=1.57, P=0.006). For obese class II/III patients, there were significantly smaller improvements in OHS and EQ-5D index (P<0.001), and greater risk of wound complications (P=0.006), readmission (P=0.001) and reoperation (P=0.003). Large improvements in patient outcomes were seen irrespective of BMI, although improvements were marginally smaller and complication rates higher in obese patients.