Assessing the Mortality Rate After Primary Total Knee Arthroplasty: An Observational Study to Inform Future Economic Analysis

Yushy Zhou; Chris Frampton; Michelle Dowsey; Peter Choong; Chris Schilling; Marc Hirner

doi:10.1016/j.arth.2023.05.070

Assessing the Mortality Rate After Primary Total Knee Arthroplasty: An Observational Study to Inform Future Economic Analysis

J Arthroplasty. 2023 Nov;38(11):2328-2335.e3. doi: 10.1016/j.arth.2023.05.070. Epub 2023 Jun 4.

Authors

Yushy Zhou¹, Chris Frampton², Michelle Dowsey³, Peter Choong³, Chris Schilling³, Marc Hirner⁴

Affiliations

¹ Department of Surgery, The University of Melbourne, Melbourne, Australia, Fitzroy, Victoria, Australia; Department of Orthopaedic Surgery, St. Vincent's Hospital, Melbourne, Victoria, Australia.
² Department of Medicine, The University of Otago, Christchurch, New Zealand.
³ Department of Surgery, The University of Melbourne, Melbourne, Australia, Fitzroy, Victoria, Australia.
⁴ Department of Orthopaedic Surgery, Whangarei Hospital, Whangarei, New Zealand.

PMID: 37279845
DOI: 10.1016/j.arth.2023.05.070

Abstract

Background: Previous research has focused on the perioperative or short-term (<1 year) mortality rate of total knee arthroplasty (TKA), leaving the long-term (>1 year) mortality rate unresolved. In this study, we calculated the mortality rate up to 15 years after primary TKA.

Methods: Data from the New Zealand Joint Registry from April 1998 to December 2021 were analyzed. Patients aged 45 years or older who underwent TKA for osteoarthritis were included. Mortality data were linked with national records from births, deaths, and marriages. To determine the expected mortality rates in the general population, age-sex-specific life tables from statistics New Zealand were used. Mortality rate was presented as standardized mortality ratios (SMRs) - a comparison of relative mortality rate between the TKA and general populations. In total, 98,156 patients with a median follow-up of 7.25 years (range, 0.00 to 23.74) were included.

Results: Over the entire follow-up period, 22,938 patients (23.4%) had died. The overall SMR for the TKA cohort was 1.08 (95% confidence interval (CI): 1.06 to 1.09), suggesting that TKA patients have an 8% higher mortality rate compared to the general population. However, a reduction in short-term mortality rate was observed for TKA patients up to 5 years post TKA (SMR 5 years post TKA; 0.59 95% CI: 0.57 to 0.60]). On the contrary, a significantly increased long-term mortality rate was observed in TKA patients with greater than 11 years of follow-up, particularly in men over the age of 75 years (SMR 11 to 15 years post TKA for males ≥ 75 years; 3.13 [95% CI: 2.95 to 3.31]).

Conclusion: The results suggest a reduction in short-term mortality rate for patients who undergo primary TKA. However, there is an increased long-term mortality rate particularly in men over the age of 75 years. Importantly, the mortality rates observed in this study cannot be causally attributed to TKA alone.

Keywords: cost-effectiveness analysis; health economics; mortality; osteoarthritis; standardised moratlity ratios; total knee arthroplasty.

Publication types

Observational Study
Research Support, Non-U.S. Gov't

MeSH terms

Aged
Arthroplasty, Replacement, Knee* / methods
Female
Forecasting
Humans
Male
Middle Aged
New Zealand / epidemiology
Osteoarthritis* / surgery
Osteoarthritis, Knee* / surgery
Registries