Women in Charnley class C fail to improve in mobility to a higher degree after total hip replacement

Abstract

Background— The Charnley comorbidity classification organizes patients into 3 classes: (A) 1 hip involved, (B) 2 hips involved, and (C) other severe comorbidities. Although this simple classification is a known predictor of health-related quality of life (HRQoL) after total hip replacement (THR), interactions between Charnley class, sex, and age have not been investigated and there is uncertainty regarding whether A and B should be grouped together.

Methods — We selected a nationwide cohort of patients from the Swedish Hip Arthroplasty Register operated with THR due to primary osteoarthritis between 2008 and 2010. For estimation of HRQoL, we used the generic health outcome questionnaire EQ-5D of the EuroQol group. This consists of 2 parts: the EQ-5D index and the EQ VAS estimates. We modeled the EQ-5D index and the EQ VAS against the self-administered Charnley classification. Confounding was controlled for using preoperative HRQoL values, pain, and previous contralateral hip surgery.

Results — We found that women in class C had a poorer EQ-5D outcome than men. This effect was mostly due to the fact that women failed to improve in the mobility dimension; only 40% improved, while about 50% of men improved. Age did not interact with Charnley class. We also found that the classification performed best without splitting or aggregating classes.

Interpretation — Our results suggests that the self-administered Charnley classification should be used in its full capacity and that it may be interesting to devote special attention to women in Charnley class C.

MGo initiated and planned the study, performed all the analyses including programming of the graphs, and wrote the draft manuscript. MGr aided by scanning of PubMed and Google Scholar for possible causes of interaction between sex and Charnley class, and helped in writing the manuscript. PF aided with the statistical analyses. OR contributed with study planning, gathering of data, and writing of the manuscript. GG contributed with study planning, gathering of data, and writing of the manuscript. OS contributed with study planning and writing of the manuscript.

We thank all of the Swedish orthopedic departments and patients for kindly supplying us with this high-quality data.

No competing interests declared.