Analysis of data from the National Joint Registry for England and Wales, UK, has identified a drop in mortality rates from 0.56% in 2003 to 0.29% in 2011 for patients with osteoarthritis (OA) undergoing primary hip replacements. Covering 409,096 of such hip replacements for OA, with 1,743 patient deaths within 90 days of surgery recorded during the 8-year period, the study investigators adjusted for age, sex and comorbidity and found four modifiable clinical factors that were associated with lower mortality: posterior surgical approach, mechanical and chemical prophylaxis, and spinal anaesthesia. Type of prosthesis had no effect, but being overweight was associated with lower mortality.