Association between disease activity of rheumatoid arthritis and risk of complications following total hip arthroplasty: a retrospective cohort study.

BACKGROUND

Identifying rheumatoid arthritis patients at higher risk of complications after total hip arthroplasty could make perioperative management more effective. Here we examined whether disease activity is associated with risk of such complications.

METHODS

We retrospectively analyzed data for 337 rheumatoid arthritis patients at our medical center who underwent primary total hip arthroplasty. Rheumatoid arthritis patients were categorized according to the simplified disease activity index (SDAI), the values of which at admission and follow-up were averaged together. Logistic regression was used to examine associations of mean SDAI with rates of dislocation, infection, periprosthetic fracture and aseptic loosening. As controls, 337 osteoarthritis patients who did not have systemic inflammation and who underwent the same procedure were matched across numerous clinicodemographic variables.

RESULTS

Among the 337 rheumatoid arthritis patients, 38 (11.3%) had postoperative complications, the rates of which varied significantly from 0 to 17.5% (p = 0.003) among the four subgroups whose disease activity based on mean SDAI was categorized as high, moderate, low or in remission. Each 1-unit increase in mean SDAI was associated with a significant increase in risk of postoperative complications (OR 1.015, 95% CI 1.001-1.029, p = 0.035). Across all rheumatoid arthritis patients, rate of complications did not differ significantly between patients who received disease-modifying anti-rheumatic drugs or other treatments. Rates of dislocation, of infection or of all postoperative complications combined were significantly lower among osteoarthritis controls than among rheumatoid arthritis patients.

CONCLUSION

Greater mean SDAI is associated with higher risk of dislocation, infection and composite postoperative complications after total hip arthroplasty in rheumatoid arthritis patients. These patients show a significantly higher rate of postoperative complications than osteoarthritis patients, likely reflecting the influence of systemic inflammation. Disease activity should be reduced as much as possible in rheumatoid arthritis patients before they undergo total hip arthroplasty.