Reliability and validation of the joint dysfunction index as a new assessment instrument for therapeutic efficacy for Kashin-Beck disease.

The objective of this study was to evaluate the reliability and validity of the joint dysfunction index (JDI) for assessment of therapeutic efficacy for Kashin-Beck disease (KBD). In an initial survey, completed questionnaires were obtained from 276 of 281 patients (98.2 %). A follow-up survey was completed with 64 KBD patients among 276 cases. A third survey selected 60 KBD patients who underwent intra-articular injection of sodium hyaluronate in the knees ascertained from the findings of the second questionnaire. Reliability was assessed using test-retest, "split-half" reliability and Cronbach's alpha coefficient. Factor analysis and item-to-domain correlation were used to analyze validity. The coefficient of variation (CV) was used to measure the sensitivity of scale. Feasibility assessment included consideration of completion time, rate of recovery, and time of completion. Reliability analysis comprised a test-retest correlation coefficient of 0.404-0.546 and a kappa test of 0.404-0.546. Internal consistency analysis comprised a Cronbach alpha coefficient of 0.689 and a split-half coefficient of 0.677. Principal component factor analysis for validity testing extracted a common factor with a cumulative variance contribution of 45.44 %. The JDI score from 276 KBD cases revealed no significant difference associated with age, gender, education, or the body mass index. Sensitivity analysis showed that there was no significant difference between pre-treatment and post-treatment values, with a CV of 96.55-172.06 %. In conclusion, the JDI can be used to evaluate the efficacy of agents used to treat KBD.