Clinical reliability and validity of elbow functional assessment in rheumatoid arthritis

Objectives, (1) To investigate the measurement characteristics of the Hospi tal for Special Surgery (HSS) and Mayo Clinic elbow assessment instruments, utilizing methodological criteria including feasibility, reliability, vali dity, and discriminative ability; and (2) to develop an efficient and disea se-specific rating system for elbow function assessment (EFA) in adult pati ents with RA, using a combination of self-reported subjective items and obj ective measures, and comparing its characteristics with the HSS and Mayo Cl inic scales. Methods, (1) Selection of elbow-specific items. (2) Investigation of reliab ility and validity of all separate items, as well as the total HSS and Mayo Clinic scores, in 42 patients with RA (mean age 60 yrs). Direct observatio n of functional elbow performance was defined as the gold standard against which criterion validity was compared. (3) Reaching agreement within a team of professionals on the different scale dimensions and the assigned weight . (4) Item reduction by eliminating unreliable, inaccurate, unfeasible, and ambiguous items, Finally, the EFA scale was constructed by selecting the m ost reliable and accurate items. Results. The EFA scale showed a superior or equal degree of reliability as reflected in intraclass correlation coefficients of more than 0.88, and als o superior validity, compared with the HSS and Mayo Clinic measures. Conclusion. Although the elbow scoring systems currently available provide a reliable measure, they seem restricted in evaluating elbow-specific funct ional ability. The EFA scale was found to be most suitable to measure elbow functional ability in RA, and was also shown to be highly reliable and pra ctical in clinical practice.