Cost and Complications in Rheumatoid Arthritis Patients Undergoing Primary Hip Arthroplasty: A National Inpatient Sample-Based Study

Introduction: Rheumatoid arthritis (RA) is an autoimmune disease that affects multiple synovial joints in the body, including the hip. Hip involvement in RA patients is fairly common, but the current literature is lacking large-scale studies on the surgical outcomes of RA patients undergoing total hip arthroplasty (THA). The aim of the study is to examine the outcomes and hospital costs associated with THA in patients with RA and compare them to patients without RA using the National Inpatient Sample (NIS) database. Methods: We analyzed the NIS database to identify patients undergoing THA between 2016 and 2019 using International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis codes. Multiple variables including demographics, medical comorbidities, total hospital costs, length of stay, and perioperative complication rates were then compared between patients with and without RA. Further, the two groups were matched for demographic differences, if any, using a 1:1 propensity match algorithm. Results: Patients with RA undergoing THA were significantly younger and predominantly female when compared to patients without RA. There was also a lower incidence of obesity and the percentage of elective THA procedures were smaller in the RA group. The RA group had a longer length of stay and increased incidences of blood loss anemia, blood transfusion, and periprosthetic fractures. These differences persisted despite matching the two groups for demographic differences, elective procedures, diabetes, obesity, and tobacco usage. Conclusion: THA in RA is associated with an increased incidence of blood loss anemia, blood transfusion, and periprosthetic fractures, as well as a longer length of stay in THA patients.