title: Impact of the economic downturn on total joint replacement demand in the United States: updated projections to 2021.
abstract: BACKGROUND
  Few studies have explored the role of the National Health Expenditure and macroeconomics on the utilization of total joint replacement. The economic downturn has raised questions about the sustainability of growth for total joint replacement in the future. Previous projections of total joint replacement demand in the United States were based on data up to 2003 using a statistical methodology that neglected macroeconomic factors, such as the National Health Expenditure.
  
  
  METHODS
  Data from the Nationwide Inpatient Sample (1993 to 2010) were used with United States Census and National Health Expenditure data to quantify historical trends in total joint replacement rates, including the two economic downturns in the 2000s. Primary and revision hip and knee arthroplasty were identified using codes from the International Classification of Diseases, Ninth Revision, Clinical Modification. Projections in total joint replacement were estimated using a regression model incorporating the growth in population and rate of arthroplasties from 1993 to 2010 as a function of age, sex, race, and census region using the National Health Expenditure as the independent variable. The regression model was used in conjunction with government projections of National Health Expenditure from 2011 to 2021 to estimate future arthroplasty rates in subpopulations of the United States and to derive national estimates.
  
  
  RESULTS
  The growth trend for the incidence of joint arthroplasty, for the overall United States population as well as for the United States workforce, was insensitive to economic downturns. From 2009 to 2010, the total number of procedures increased by 6.0% for primary total hip arthroplasty, 6.1% for primary total knee arthroplasty, 10.8% for revision total hip arthroplasty, and 13.5% for revision total knee arthroplasty. The National Health Expenditure model projections for primary hip replacement in 2020 were higher than a previously projected model, whereas the current model estimates for total knee arthroplasty were lower.
  
  
  CONCLUSIONS
  Economic downturns in the 2000s did not substantially influence the national growth trends for hip and knee arthroplasty in the United States. These latest updated projections provide a basis for surgeons, hospitals, payers, and policy makers to plan for the future demand for total joint replacement surgery.
authors.affiliation: Exponent, Inc., 3440 Market Street, Suite 600, Philadelphia, PA 19104. E-mail address for S.M. Kurtz: skurtz@exponent.com.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Kurtz
authors.affiliation: Exponent, Inc., 3440 Market Street, Suite 600, Philadelphia, PA 19104. E-mail address for S.M. Kurtz: skurtz@exponent.com.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Ong
authors.affiliation: Exponent, Inc., 149 Commonwealth Drive, Menlo Park, CA 94025.
authors.forename: Edmund
authors.initials: E
authors.lastname: Lau
authors.affiliation: University of California San Francisco Department of Orthopaedic Surgery, Institute for Health Policy Studies, 3333 California Street, Suite 265, Box 0936, San Francisco, CA 94118.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Bozic
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data* / Q000639:trends; D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data* / Q000639:trends; D057172:Economic Recession / Q000706:statistics & numerical data / Q000639:trends*; D005544:Forecasting; D006301:Health Services Needs and Demand / Q000191:economics* / Q000706:statistics & numerical data* / Q000639:trends; D006801:Humans; D012086:Reoperation / Q000706:statistics & numerical data / Q000639:trends; D014481:United States / Q000453:epidemiology