# Explanatory factors for the survival benefit among hip and knee arthroplasty patients with osteoarthritis

## TL;DR

Hip and knee replacement patients with osteoarthritis in the Netherlands live longer than the general population, but health and socioeconomic factors only partly explain this survival benefit.

## Contribution

This study confirms the survival benefit of THA/TKA patients in the Netherlands and shows that health and socioeconomic status explain only a small portion of this benefit.

## Key findings

- Eleven-year survival of THA and TKA patients was 8.7% and 8.1% better than the general population.
- Health and socioeconomic status explained only about 7% of the survival benefit.
- The study raises questions about other potential explanations for the survival advantage.

## Abstract

Studies have shown that osteoarthritis patients who underwent a primary total hip or knee arthroplasty (THA/TKA) experience better survival than the general population, yet there is limited evidence explaining this counter-intuitive difference. We investigated whether this better survival is also present in the Netherlands and to what extent it could be explained by a patient selection effect, whereby patients with more favorable health and socioeconomic status (SES) are more likely to receive THA/TKA.

In this registry-based study, we compared the survival, health and SES of THA/TKA osteoarthritis patients to those of the general Dutch population. The patient cohort included 224,785 THA and 198,691 TKA patients who underwent an arthroplasty between 2010–2020. The proportions of the survival differences explained by better health (as measured by the EQ-5D) and SES (postcode-level) were estimated using spline-based survival models and Dutch lifetables.

The eleven-year survival of THA and TKA patients were 8.7% and 8.1% better than the general population. Although health and SES predicted individual survival, they explained only ≈7% of the survival benefit.

Our study confirmed that Dutch osteoarthritis THA/TKA patients experience better survival than the general population, but raises important questions as to the explanation. A more favorable health status and/or SES did not explain most of the survival benefit. This may be partly due to limitations of the available measures of health and SES in our study, but also leaves other explanations (e.g. barriers to receive access to care, lifestyle changes) open for further research.