Background: Preoperative patient characteristics may influence patient choice for participating in RCT’s.

Purpose / Aim of Study: This study aimed to compare patient characteristics, level of pain, physical function and joint space width in patients with severe hip osteoarthritis (OA) who accepted or refused to participate in a RCT.

Materials and Methods: In this prospective cohort study a total of 137 patients with primary hip OA were asked to choose between surgical or non- surgical treatment. We then compared the characteristics of each patient cohort (demographics, pain level and duration, analgesic use, exercise habits), the radiographic hip OA state and their responses to Hip dysfunction and Osteoarthritis Outcome Score (HOOS, 0-100) and European Quality of Life Scale (EQ-5D-5L) questionnaires.

Findings / Results: The between-group HOOS scores were significantly different in three out of the five HOOS subscales analyzed; HOOSpain 6.1 (95% CI: 0.3 to 12.5), HOOSADL 8.3 (95% CI: 2.3 to 14.4) and HOOSsport/rec 8.6 (95% CI: 3.2 to 13.9) with higher scores recorded in the non-surgical patient cohort indicating less symptoms. Overall health status (EQ-5D-5L) showed surgical patients had more problems in all the dimensions except for the EQanxity/depression responses. The surgical patients had significantly reduced joint space width (1.2 ± 1.0 mm vs. 1.8 ± 1.2 mm, p = 0.004) and both cohorts had values below the defined 2 mm cut-off (Jacobsen et al.).

Conclusions: Patients, who choose surgical treatment had preoperatively more pain, reduced physical function, lower health status and joint space width compared with patients who choose non-surgical treatment.