Factors influencing health-related quality of life after total hip replacement - a comparison of data from the Swedish and Danish hip arthroplasty registers

Background: There is an increasing focus on measuring patient-reported outcomes (PROs) as part of routine medical practice, particularly in fields such as joint replacement surgery where pain relief and improvement in health-related quality of life (HRQoL) are primary outcomes. Between-country comparisons of PROs may present difficulties due to cultural differences and differences in the provision of health care. However, in order to understand how these differences affect PROs, common predictors for poor and good outcomes need to be investigated. This cross-sectional study investigates factors influencing health-related quality of life (HRQoL) one year after total hip replacement (THR) surgery in Sweden and in Denmark. Methods: Data was retrieved from the Swedish (n = 14 560 patients) and Danish (n = 632 patients) Hip Arthroplasty Registers according to preset selection criteria. Using linear regression models, we examined how sex, age, comorbidity and country of surgery were associated with different aspects of HRQoL as measured by the EQ-5D index and EQ VAS. Results: Danish patients had an overall higher EQ-5D index and EQ VAS than Swedish patients (p < 0.001). After regression analysis, the estimated coefficients for sex, age, or the Charlson score did not differ between countries for either the EQ-5D index (p = 0.83) or EQ VAS (p = 0.41) one year after THR. Conclusions: We conclude that there are clear similarities in how basic predictors influence patient-reported outcomes (PROs) in patients with THR in Sweden and Denmark and these known predictors of good or poor HRQoL outcomes are not specific for each country.