Lifetime risk of total knee replacement and temporal trends in incidence by health care setting, socioeconomic status, and geographic location

Objective To estimate the lifetime risk of total knee replacement (TKR) and examine temporal trends in TKR incidence in the state of Victoria, Australia. Methods We performed a retrospective analysis of a population-based longitudinal cohort of patients (ages ≥40 years) who received a primary TKR in Victoria from 1999-2008. Hospital separations and life tables were used to estimate lifetime risk. Temporal changes in TKR incidence were examined according to health care setting (public versus private), socioeconomic status (SES), and geographic location (regional versus metropolitan). Results There were 43,570 incidents of primary TKRs identified over the study period. In 2008, the lifetime risk of surgery was 10.4% (95% confidence interval [95% CI] 10.13-10.64%) for men and 11.9% (95% CI 11.63-12.13%) for women. TKRs increased steadily over the study period in private hospitals (overall increase of 90%) with a smaller growth in procedure numbers for public hospitals (overall increase of 40%). From 2002-2003 onward, the low SES tertile showed a lower incidence of TKR compared to the middle and high SES groups, with incidence rates of 1.09 (95% CI 1.04-1.15), 1.22 (95% CI 1.17-1.28), and 1.20 (95% CI 1.16-1.25) per 1,000 population, respectively (based on 2007-2008 figures). Increased numbers of TKRs were also found to be occurring among people residing in regional areas of Victoria (from 1.12 [95% CI 1.04-1.31] to 1.84 [95% CI 1.72-2.02] per 1,000 population). Conclusion Increases in lifetime risk of TKR were evident. Although improved access to TKR for those living in regional areas was observed, sustained disparities relating to health care setting and SES warrant further investigation.