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Published on: February 27, 2018
How Does Mortality Risk Change Over Time After Hip and Knee Arthroplasty?
Ian A Harris1, Alesha Hatton, Nicole Pratt
1I. A. Harris, J. M. Naylor, Ingham Institute for Applied Medical Research, South Western Sydney Clinical School, Faculty of Medicine, UNSW Sydney, Liverpool, Australia I. A. Harris, Institute for Musculoskeletal Health, School of Public Health, Faculty of Medicine, University of Sydney, NSW, Australia I.A. Harris, R. de Steiger, P. Lewis, S. E. Graves, Australian Orthopaedic Association National Joint Replacement Registry, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia A. Hatton, M. Lorimer, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia N. Pratt, S. E. Graves, University of South Australia, Adelaide, South Australia, Australia R. de Steiger, Department of Surgery, Epworth Healthcare, University of Melbourne, Melbourne, Victoria, Australia.
Mortality after hip and knee replacements is initially lower than expected but becomes higher than expected after 12 years. Further research is needed to understand the causes of this increased long-term mortality after total hip arthroplasty (THA) and total knee arthroplasty (TKA).
Area of Science:
- Orthopedic surgery outcomes research
- Long-term patient survival analysis
- Epidemiology of joint replacement surgery
Background:
- Post-arthroplasty mortality is often lower than population norms in the initial years following total hip arthroplasty (THA) and total knee arthroplasty (TKA).
- Long-term follow-up data suggests a potential reversal of this trend, with mortality possibly exceeding expected rates beyond approximately 10 years.
- The extent and implications of this late-term mortality shift after THA and TKA remain incompletely established.
Purpose of the Study:
- To investigate the long-term mortality rates following THA and TKA.
- To compare postsurgical mortality with expected mortality, adjusted for age, sex, and calendar year.
- To quantify the temporal trends in mortality after joint replacement surgery.
Main Methods:
- Analysis of a large registry study including 243,057 THAs and 363,355 TKAs for osteoarthritis.
- Utilized data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 2003 to 2016.
- Calculated Standardised Mortality Ratio (SMR), relative mortality, and excess mortality using Australian Bureau of Statistics life tables, with follow-up up to 13 years.
Main Results:
- Initially, THA and TKA patients exhibited lower-than-expected mortality.
- This trend reversed, with mortality exceeding expected rates after 12 years for both procedures.
- For THA, excess mortality shifted from -11 deaths/1000 at 1 year to +4 deaths/1000 at 13 years (SMR 0.50 to 1.07); for TKA, it shifted from -12 deaths/1000 to +5 deaths/1000 (SMR 0.39 to 1.09).
Conclusions:
- Mortality after hip and knee arthroplasty is lower than expected for approximately 8-9 years, then increases, surpassing expected rates after 12 years.
- The initial lower mortality is likely due to healthier patient selection for primary arthroplasty.
- The reasons for increased late mortality require further investigation, considering factors like obesity, osteoarthritis, and implant characteristics.
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