How to evaluate the clinical outcome of joint-preserving treatment for osteonecrosis of the femoral head: development of a core outcome set

Background This study aimed to develop a core outcome set (COS) for clinical trials of joint-preserving treatment for osteonecrosis of the femoral head (ONFH), that is, to define a minimal set of outcomes that should be reported in such trials. Methods A mixed research method was adopted in this study. First, clinical trials of hip preservation therapy were systematically researched and analyzed. Second, a three-round Delphi survey involving both doctors and patients was carried out to obtain the core outcome indicators. Round 1 was a modified Delphi questionnaire for doctors and patients to determine which outcomes are important to these stakeholders, round 2 determined what clinical evaluation core outcomes should be included for the joint-preserving treatment of ONFH, and round 3 determined how core outcomes should be measured. Finally, a consensus meeting was held to discuss and vote on the established COS. Results The results of the systematic review showed that 42 outcome indicators were classified according to common signs and symptoms, quality of life, long-term outcomes, radiological evaluation, blood biochemistry, and indexes of safety. The three rounds of Delphi surveys completed the selection of indicators for the COS and the determination of the corresponding measurements. A total of 73 orthopedic doctors and 103 patients participated in round 1, and the top 10 indicators selected were basically the same. In round 2, 32 experts identified the following indicators: pain, range of motion (ROM) of hip flexion, walking distance, and stable rating of X-ray images. In round 3, 35 experts defined the measurement of each indicator. Finally, the consensus meeting identified the four indicators aforementioned that constituted the COS. The scores for pain, ROM of hip flexion, and walking distance are from 0 to 10; 0 represents the best scores, while 10 represents the most serious impairment. The stable rating of X-ray images is determined by the morphology of the femoral head and the change in the density of the necrotic area. Conclusions We established a COS for hip-preserving treatment of ONFH that includes four indicators: pain, ROM of hip flexion, walking distance, and stable rating of X-ray images.