Christian Fugl Hansen

Purpose: The purpose of this study was to analyse the structural validity of the preliminary paediatric Knee Numeric‐Entity Evaluation Score‐Anterior Cruciate Ligament (KIDS‐KNEES‐ACL) Version 1.0 by Rasch analysis and Confirmatory Factor Analysis (CFA), to establish a final item‐reduced and structurally valid KIDS‐KNEES‐ACL Version 2.0. Methods: KIDS‐KNEES‐ACL Version 1.0 is a content‐valid patient‐reported outcome measure (PROM) for the evaluation of children and adolescents with anterior cruciate ligament (ACL) deficiency. It consists of 60 items across 9 subscales. KIDS‐KNEES‐ACL Version 1.0 was completed by patients from a national cohort of children treated with ACL reconstruction. For each subscale, structural validity was evaluated by fit to the Rasch model for 141 respondents. Item fit, local dependence (LD), and Differential Item Functioning (DIF) for age and sex were assessed. These properties guided the process of item reduction until an adequate fit to the Rasch model was reached. The structure, as suggested by the Rasch model, was confirmed with CFA. Internal consistency was evaluated by Cronbach's α . Results: Rasch analysis revealed item misfit of four of 60 items, and LD for several items across all subscales. When adjusted for, omitting 16 items from the item pool, excellent item fit statistics were achieved. Four subscales could be merged into the two new ‘Friends and Family’ and ‘Looseness and Weakness’ subscales. CFA confirmed the structure of all subscales with excellent χ ² fit ( p > 0.05) without further modification. Internal consistency was acceptable with α values ranging from 0.71 to 0.88. There was no evidence of DIF with respect to age or sex. Conclusion: The KIDS‐KNEES‐ACL 2.0, consisting of 44 items across seven subscales, is a new content‐valid and structurally valid PROM for children and adolescents with ACL deficiency. It can serve as an evaluative outcome for ACL injury and reconstruction. Level of Evidence: N/A.

Purpose: The existing knee‐specific pediatric patient‐reported outcome measures (PROMs) lack content and construct validity for children with anterior cruciate ligament (ACL) injury. This impairs their accuracy which can lead to false interpretations of data and inaccurate clinical guidelines. The purpose of this study was to develop a content‐valid PROM for children with an ACL injury.Methods: The process adhered to the COnsensus‐based Standards for the selection of health Measurement INstruments guidelines for PROM development. Informants were children with ACL deficiency and sampled based on age, sex, and treatment. Semistructured interviews were conducted exploring themes within the International Classification of Functioning, Disability and Health model. Interviews continued beyond data saturation. By thematic analysis and by probing items from the adult PROM ‘KNEES‐ACL’, new themes and items emerged. Content coverage, relevance and understandability were continuously evaluated. All interviews were recorded and transcribed verbatim. The NVivo 12 software was used for data analysis and coding of items.Results: A PROM of 60 items across nine subscales was formed. From cognitive interviews, 19 new items emerged. Forty‐one of 55 items from KNEES‐ACL were endorsed as relevant; however, all required rewording to ensure understandability. Substantial differences in the psychosocial impact between adults and children were observed. The children experienced a more considerable negative psychosocial impact caused by a loss of participation in sports, lower self‐confidence and loss of social networks. This resulted in four new domains. The physical issues were similar to adults, with few exceptions.Conclusion: The ‘KIDS‐KNEES‐ACL’ 1.0 (qualitative version) was developed. This version will be subjected to psychometric analysis, resulting in adequate measurement properties of the final KIDS‐KNEES‐ACL 2.0. As the only adequate pediatric ACL‐specific PROM, its use in clinical trials and databases will enhance PROM data quality, and strengthen clinical guidelines and thus the treatment of children with ACL injury.Level of Evidence: Not applicable

Objectives Knee injury and Osteoarthritis Outcome Score (KOOS)-Child is a modification of the adult KOOS aiming to evaluate knee injury, including ACL deficiency. However, the measurement properties of KOOS-Child have not been assessed in a cohort of children with ACL deficiency. We aimed to study the structure of KOOS-Child using modern test theory models (Rasch analysis and confirmatory factor analysis (CFA)). Methods Data were collected prospectively in a cohort of children with ACL deficiency at three time points: before-and-after ACL surgery, and at 1-year follow-up. For each subscale, structural validity through the fit of a CFA model was evaluated for 153 respondents. Modification indices were examined to find the model of best fit, confirmed using Rasch analysis. Responsiveness was reported for each subscale. Reliability was calculated for each item. Floor and ceiling effects, and Person-item distribution were reported. Results All subscales showed inadequate fit to a unidimensional CFA model. Rasch analysis confirmed these results. Adjusting the subscales improved model fit, although this was still quite poor, except for the quality of life subscale. With one exception, all items demonstrated ceiling effects. Person-item distribution confirmed this. Due to lack of fit, reliability was not reported. All subscales were able to detect change from baseline to 1-year follow-up. Conclusions KOOS-Child exhibits inadequate measurement properties in its current form for children with ACL deficiency. Suggestions to make the subscales fit the models better and improve accuracy of KOOS-Child are presented. However, the large ceiling effects observed may reduce sensitivity and induce type 2 errors.

Purpose: Content validity is the most important property of PROMs. The COSMIN initiative has published guidelines for evaluating the content validity of PROMs, but they have only sparsely been applied to relevant PROMs for musculoskeletal conditions. The aim of this study was to use the COSMIN Risk of Bias checklist to evaluate the content validity of five PROMs, that are highly relevant in musculoskeletal research and used by the arthroscopic surgery community: the modified Harris’ Hip Score (mHHS), the Copenhagen Hip and Groin Outcome Score (HAGOS), the International Knee Documentation Committee Subjective Knee evaluation Form (IKDC‐SKF), the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Knee Numeric‐Entity Evaluation Score ACL (KNEES‐ACL).Methods: The development articles for the five PROMs were identified through searches in PubMed and SCOPUS. A literature search was performed to identify additional studies assessing content validity of the PROMs. Additional information, necessary for the assessments, was obtained from the PROM developers after direct request. To evaluate the quality of the development studies and rate the content validity, the COSMIN Risk of Bias checklist was applied to all studies.Results: All five development studies were identified. Three subsequent content validity studies were identified, all evaluating KOOS and one also IKDC. One content validity study was of inadequate quality and excluded from further analysis. The development of mHHS, IKDC‐SKF, and KOOS was rated inadequate and possess insufficient content validity for their target populations. Due to the irrelevance of multiple items, KOOS was in particular inappropriate to evaluate patients with an ACL injury. The development of HAGOS was also rated inadequate, although the insufficiency aspects can be regarded as minor. KNEES‐ACL possessed sufficient content validity.Conclusion: Out of five PROMs, only KNEES‐ACL possessed sufficient content validity. Particularly, KOOS should not be used as an outcome for patients with an ACL injury. There is an urgent need for condition‐specific PROMs for musculoskeletal conditions, developed with adequate methods.Level of evidence: III.

Choosing the most adequate PROM for a study is a non‐trivial process. The aim of this study was to provide a catalogue with analyses of content and construct validity of PROMs relevant to research in sports science, including all published local translations. The most commonly used PROMs in sports research were selected from a PubMed search “patient reported outcome measures sports”, identifying 439 articles and 194 different PROMs. Articles describing development of the 61 selected PROMs were assessed for content validity, and all articles regarding construct validity of each PROM and all published translations (in total 622 articles) were analyzed. A catalogue with assessments of the 61 PROMs was produced. The majority were of inferior validity, with few exceptions. The most common reason for this was that the PROM had not been developed by methods that ensure high content validity. Another major reason for inferior validity was that construct validity had not been secured by adequate statistical methods. In conclusion, this catalogue provides a tool for researchers to facilitate choosing the most valid PROM for studies in sports research. Furthermore, it shows for popular PROMs where further validation is needed, and for fields in musculoskeletal medicine where valid PROMs are lacking. It is suggested that a targeted effort is made to develop valid PROMs for major conditions in musculoskeletal research. The current method is easier to practice compared with assessment after COSMIN guidelines.

Choosing the most appropriate patient‐reported outcome measure (PROM) for a clinical study is essential in order to achieve trustworthy results. This choice will depend on (a) the objective of the study and hence the research question; (b) the choice of a theoretical framework, such as the World Health Organization's International Classification of Functioning, Disability, and Health (ICF); (c) whether there currently is a PROM that possesses high content validity and high construct validity for the specific patient group and objective, and if not; (d) the decision on whether to use a suboptimal PROM or develop and validate a new PROM. This paper presents the steps that should be followed in order to assess the relevance of PROMs and suggests ways to enhance the choice depending on the goal of the study.