Summary

This study compares complication rates in total knee arthroplasty between Japanese patients aged 90 years and older and those aged 80-89 using inverse probability of treatment weighting, revealing a significantly higher risk of in-hospital mortality, delirium, and DVT in the older age group.

Abstract

Introduction

As the population ages, total knee arthroplasty (TKA) performed in elderly patients has been increasing. While several studies have reported complications in patients aged over 80 years, no study has specifically assessed patients over 90 years. The purpose of this study is to clarify the risk of complications in TKA among patients aged 90 years and older, compared to those in their 80s.

Methods

Patients who underwent TKA between 2016 and 2021 were analyzed using a Japanese claims database. Complications were compared between patients aged 80-89 years and those aged 90 years and older. The primary outcome was the complication of in-hospital mortality. The secondary outcomes included ther occurrence of infection, reoperation, delirium, deep vein thrombosis (DVT), pulmonary embolism (PE) and length of hospital stay. A stabilized inverse probability of treatment weighting (sIPTW) was performed using the covariates of sex, body mass index and Barthel index.

Results

SECTION:
Among 211,048 TKAs, 58,793 (27.9%) were performed on patients in the 80-89 age group, and 1,526 (0.72%) on patients in the over 90 age group.
After adjustment with sIPTW, the risk of in-hospital mortality was significantly higher in the over 90 age group compared to the 80-89 age group, with an adjusted odds ratio (OR) of 4.00 [95% CI: 1.70 – 9.42]. Similarly, the risk of delirium was also significantly higher in patients over 90, with an adjusted OR of 2.35 [95% CI: 1.26 – 4.40]. Additionally, the length of hospital stay was longer in the over 90 age group.

Discussion

This is an observational study based on a large-scale nationwide database evaluating complications in the super-elderly population aged 90 years and older, including over 1,500 subjects. Previous studies have reported that TKA patients aged 80 years and older have higher rates of complications, including mortality, DVT and delirium compared to younger patients. In this study, patients aged 90 years and older were compared with those aged 80-89 years, further adjusting for baseline characteristics using sIPTW, and it was found that the odds ratio of in-hospital death and delirium increased by 4.00 and 2.35, respectively, in the older cohort. These findings suggest that even with similar patient backgrounds, in-hospital mortality following TKA significantly increases in patients aged 90 years and older.

SIGNIFICANCE/CLINICAL RELEVANCE:
There are few reports on outcomes in TKA patients aged 90 years and older. These findings could be valuable for informed consent and preoperative risk assessment.