Statistical validity and reliability of the Persian version of the Western Ontario Meniscal Evaluation Tool (WOMET) according to the COSMIN checklist

BACKGROUND: The Western Ontario Meniscal Evaluation Tool (WOMET) is the only questionnaire available to assess quality of life in patients with isolated meniscal injuries. The aims of this study were to prepare the Persian version of the WOMET (PWOMET) and validate it in Iranian patients with isolated meniscal tears. METHODS: In the first stage, the English version of WOMET was translated into Persian. Content validity, and qualitative and quantitative (impact score) face validity were tested by specialists and in a sample of 30 patients. In the second stage, PWOMET was assessed for the evaluation of psychometric properties in 100 patients with isolated meniscal injury and 50 healthy people based on the COSMIN checklist. Construct validity was tested based on structural validity (factor analysis) and hypothesis testing. Correlation with the total scores on the SF-36, IKDC and KOOS were used for concurrent criterion validity. Test-retest reliability and internal consistency were calculated using intraclass correlation coefficient (ICC) and Cronbach’s alpha, respectively. In addition the standard error of measurement (SEM) and smallest detectable change were calculated. Interpretability was investigated as the ceiling and floor effects and minimal important difference. RESULTS: The PWOMET had acceptable qualitative face validity and content validity. The impact score (quantitative face validity) was more than 1.5 for all items. For construct validity, structural validity (factor analysis) and hypothesis testing ability were confirmed. Correlations between the PWOMET total score and IKDC, SF-36, KOOS scores were 0.61, 0.54 and 0.63, respectively (p < 0.001), thus confirming concurrent criterion validity. The intraclass correlation coefficient, Cronbach’s alpha, SEM and smallest detectable change for the PWOMET were 0.73, 0.89, 9.43 and 26.13, respectively. The PWOMET had no ceiling or floor effects, and minimal important difference was 9.07. CONCLUSION: The PWOMET provides valid and reliable scores for assessment of the quality of life in patients with isolated meniscal injury.