DOS 2020

DOS Kongressen 2020 · 15 Projection of primary knee arthroplasty in Denmark from 2020 to 2050 Louise Ujunma Kiesbye Holm, Thomas Jakobsen, Poul Torben Nielsen, Mathias Bæk Rasmussen, Anders El-Galaly Department of Clinical Medicine, Department of Orthopaedic Surgery , Aalborg University; Aalborg University Hospital, Denmark Background: The annual number of primary knee arthroplasties has increased in the past decades, however the future incidence and prevalence of primary knee arthroplasty in Denmark is unknown. Purpose / Aim of Study: The aim of this study is to estimate the incidence of primary knee arthroplasty in Denmark from 2020 to 2050. Materials and Methods: 138,298 primary knee arthroplasties conducted from 1997 to 2019 were retrieved from the Danish Knee Arthroplasty Registry. Censuses and mortality rates from 1997 to 2019 as well as population projec- tions from 2020 through 2050 were collected from Statistics Denmark. The incidence, the absolute number and the estimated prevalence of primary knee arthroplasty – based on the cumulative sum of primary knee arthroplasties and Danish mortality rates - was calculated between 1997 and 2019. Several mod- els (exponential, linear, logistic and Gompertz) were applied to the data and mean squared error was used as a quality estimator of the models’ fit to the data points. The incidence forecasts were presented with 95% confidence interval. From the incidence forecasts, we estimated the absolute yearly number of pri- mary knee arthroplasties. Findings / Results: The incidence from 1997 to 2009 has increased by more than 300%, but since 2009 the increase has stalled. Logistic and Gompertz regression had the lowest mean squared error and both assume an asymptote (i.e. a maximal incidence), wherefore these models were used to forecast the future incidence. Both regressions estimated that the incidence will soon reach a plateau and thus, the maximum incidence will be reached in 2025 at 250 (237- 262) per 100,000 by logistic regression or in 2035 at 260 (241-279) per 100,000 by Gompertz regression. Due to the aging population, both scenarios will result in a rise in the annual number of knee arthroplasties ranging from 10,388 (logistic) to 10,819 (Gompertz). Conclusions: The incidence seems to have plateaued or near its plateau, how- ever the absolute number of primary knee arthroplasty will continue to increase as the Danish population gets older. The Danish healthcare system ought to prepare for an increase in primary knee arthroplasties as well as revisions in the future. 9.