The German version of the KOOS-Child questionnaire (Knee injury and Osteoarthritis Outcome Score for children) shows a good to excellent internal consistency and a high test–retest reliability in children with knee problems

Abstract

Purpose The Knee Injury Osteoarthritis Outcome Score for children (KOOS-Child) is a self-administered, valid and reliable questionnaire for children and adolescents with knee disorders such as Osgood Schlatter disease, anterior knee pain, and patella dislocation. This study aimed to cross-culturally adapt the German version of the KOOS-Child questionnaire and test the reliability in two groups of children, one treated conservatively and the other surgically. Methods A forward–backward translation of the original questionnaire into the German language was conducted. Children and adolescents between 10 and 18 years of age with knee disorders were included. Two groups were compared: sample one consisted of 24 participants with knee pain [20.8% boys; mean age = 13.4 (1.8) years treated conservatively. These participants completed the KOOS-Child questionnaire twice within two weeks to assess test–retest reliability. The second sample included 23 subjects (21.7% boys; mean age = 15.3 (1.9) years] treated surgically due to a knee disorder. They completed the questionnaire before surgery and six months postoperatively. Test–retest reliability and internal consistency were assessed using Spearman’s rank correlation and Cronbach’s alpha. Results All subscales showed a good to excellent internal consistency at both measurement points in both groups (conservatively treated group: a = 0.88–0.95; surgery group a = 0.80–0.91), with the exception of the subscale knee problems (conservatively treated: a = 0.60 and 0.52; surgery: α = 0.77 and 0.66). Test–retest reliability was between r = 0.85 and 0.94. Conclusion The predominantly good to excellent internal consistency and the high test–retest reliability justifies the use of the German adaptation of the KOOS-Child questionnaire as a reliable multidimensional instrument for measuring health status and therapeutic effects in adolescents’ knee disorders.

The Moroccan Knee Osteoarthritis Outcome Score (KOOS)-Child Scale: Translation, Cultural Adaptation, and Validation

“…It exhibited good test-retest reliability, as all ICCs were above 0.80 for all subscales. These findings are consistent with the validation results of the German and Egyptian versions of the scale [ 28 , 29 ].…”

“…The Moroccan version of the KOOS-Child scale demonstrated excellent internal consistency, as all Cronbach's α values were greater than 0.90, except for the symptoms subscale (α = 0.470). This finding is consistent with validation results from the German version of the KOOS-Child scale, which reported a Cronbach's α value of 0.6 for the symptom subscale at T1 and 0.52 at T2 [ 28 ]. Similar results were observed in the French Canadian version, where Cronbach's α values for the symptom subscale were 0.622 in cases and 0.572 in the control group [ 30 ].…”

“…When both questions were removed simultaneously, the internal consistency increased further (α = 0.910). This suggests that the internal consistency of this subscale was affected by these specific questions, particularly as they were also responsible for decreasing the internal consistency of the symptoms subscale in the French Canadian version [ 30 ] and the German version [ 28 ]. The likely explanation is that some children misunderstood or misinterpreted the choices of these questions, which ranged from never to always .…”

Quality of patient- and proxy-reported outcomes for children with impairment of the lower extremity: A systematic review using the COnsensus-based Standards for selection of health Measurement INstruments methodology

“…Reliability : Twenty-one studies 21 – 23 , 26 , 27 , 29 , 31 – 33 , 36 , 38 , 39 , 41 , 45 , 46 , 48 , 49 – 51 , 53 reported on the test–retest reliability of the instrument. Four studies reported no intraclass correlation coefficient (ICC) values or ICC values ranging below <0.7, thus demonstrating insufficient evidence on the quality of the test–retest reliability of the instrument.…”

A Novel Scale for Evaluating Digital Readiness toward Earthquakes: A Comprehensive Validity and Reliability Analysis

“…Additionally, a two-week gap provided a balance between allowing for any genuine changes in participants' experiences related to the measured constructs and maintaining their engagement and commitment to the study. Research suggests that a two-week period strikes a reasonable balance for assessing the reliability of measures, without introducing substantial changes in participants' cognitive or situational contexts [35][36][37]. This approach aligns with established practices in reliability testing and enhanced the robustness of the study findings.…”