Projected increase in total knee arthroplasty in the United States – an alternative projection model

TLDR

The study estimates future incidence and volume of primary total knee arthroplasty in the United States from 2015 to 2050 using a conservative projection model that assumes a maximum incidence rate, and compares these projections to an exponential growth model used in prior studies. Using a population‑based epidemiological design, the authors analyzed US National Inpatient Sample and Census data on primary TKA from 1993 to 2012, calculated incidence rates per 100,000 adults over 40, and applied logistic regression for a conservative model and Poisson regression for an exponential growth model. The conservative logistic model projects a 69% rise in incidence (from 429 to 725 per 100,000) and a 143% increase in TKA volume by 2050, whereas the exponential Poisson model forecasts a 565% rise in incidence (to 2,854 per 100,000) and an 855% volume increase.

Abstract

ObjectiveThe purpose of our study was to estimate the future incidence rate (IR) and volume of primary total knee arthroplasty (TKA) in the United States from 2015 to 2050 using a conservative projection model that assumes a maximum IR of procedures. Furthermore, our study compared these projections to a model assuming exponential growth, as done in previous studies, for illustrative purposes.MethodsA population based epidemiological study was conducted using data from US National Inpatient Sample (NIS) and Census Bureau. Primary TKA procedures performed between 1993 and 2012 were identified. The IR, 95% confidence intervals (CI), or prediction intervals (PI) of TKA per 100,000 US citizens over the age of 40 years were calculated. The estimated IR was used as the outcome of a regression modelling with a logistic regression (i.e., conservative model) and Poisson regression equation (i.e., exponential growth model).ResultsLogistic regression modelling suggests the IR of TKA is expected to increase 69% by 2050 compared to 2012, from 429 (95%CI 374–453) procedures/100,000 in 2012 to 725 (95%PI 121–1041) in 2050. This translates into a 143% projected increase in TKA volume. Using the Poisson model, the IR in 2050 was projected to increase 565%, to 2854 (95%CI 2278–4004) procedures/100,000 IR, which is an 855% projected increase in volume compared to 2012.ConclusionsEven after using a conservative projection approach, the number of TKAs in the US, which already has the highest IR of knee arthroplasty in the world, is expected to increase 143% by 2050.