The most dependable patient-reported outcomes (PROs) for people with femoroacetabular impingement (FAI) is unknown because there have been no direct comparisons of questionnaires. Therefore, the aim the researchers set out with was to evaluate the test-retest reliability of six existing PROs in a single cohort of young active people with hip/groin pain consistent with a clinical diagnosis of FAI. Young adults with clinical FAI completed six PRO questionnaires on two occasions, 1-2 weeks apart. The PROs were modified Harris Hip Score, Hip dysfunction and Osteoarthritis Score, Hip Outcome Score, Non-Arthritic Hip Score, International Hip Outcome Tool, Copenhagen Hip and Groin Outcome Score. 30 young adults (mean age 24 years, SD 4 years, range 18-30 years; 15 men) with stable symptoms participated. Intraclass correlation coefficient values varied from 0.73 to 0.93 suggesting that most questionnaires reached minimal reliability benchmarks. Measurement error at the individual level was rather big for most questionnaires. In contrast, measurement error at the group level was quite small for most questionnaires.
The study found that most of the questionnaires were reliable and accurate enough for use at the group level. Samples of only 23-30 individuals were required to achieve acceptable measurement variation at the group level. Also, more direct comparisons of these questionnaires are required to assess other measurement properties such as validity, responsiveness and meaningful change in young people with FAI.