Trunk Impairment Scale - Adaptation and Validation in French

Content validity

he validity of the content is evaluated at four levels, described in detail in the methodology section of the translation and cross-cultural adaptation phase: By the reading committee (for the translation, reconciliation, and back-translation phases) By a group of professional experts in the field (to approve or not the pre-final versions) By comparing the items of the original TIS with its back-translation, by Prof. Verheyden and his team By a cognitive interview with patients, to assess the proper understanding of each item.

intra-examiner reliability

The TIS is administered several times by the same examiner at different moments. It is also considered as "the degree to which patients' scores remain the same during repeated measurements under several conditions" over time (test-retest), by the same person at different moments (intra-examiner), and at the same moment by different observers (inter-examiner). Two indices are used: * Cohen's Kappa coefficient, which determines the level of agreement to compare results item by item. Kappa is used for dichotomous item results, and weighted Kappa for ordinal item results. According to Landis and Koch, agreement is considered strong above 0.6. * The intraclass correlation coefficient (ICC) to compare the sub-scores and total scores of the scale. An ICC above 0.8 indicates excellent reliability, between 0.8 and 0.6 good reliability, between 0.6 and 0.4 moderate reliability, and below 0.4 low reliability.

inter-examiner reliability

The TIS is administered at the same moment by different observers. It is also considered as "the degree to which patients' scores remain the same during repeated measurements under several conditions" over time (test-retest), by the same person at different moments (intra-examiner), and at the same moment by different observers (inter-examiner). Two indices are used: * Cohen's Kappa coefficient, which determines the level of agreement to compare results item by item. Kappa is used for dichotomous item results, and weighted Kappa for ordinal item results. According to Landis and Koch, agreement is considered strong above 0.6. * The intraclass correlation coefficient (ICC) to compare the sub-scores and total scores of the scale. An ICC above 0.8 indicates excellent reliability, between 0.8 and 0.6 good reliability, between 0.6 and 0.4 moderate reliability, and below 0.4 low reliability.

Internal Consistency

To assess the internal consistency of behavioral and clinical items. Internal consistency reflects the interrelationship between items and indicates whether each item measures the same underlying construct. Cronbach's alpha coefficient will be calculated. Values \> 0.7 indicate good internal consistency; values close to 1 may indicate redundancy.

Standard Error of Measurement

To calculate the Standard Error of Measurement (SEM) for behavioral and clinical scores. SEM quantifies the variability of repeated measurements and reflects measurement error. It can be influenced by the examiner, the measurement tool, or the patient. SEM is used to compute the Minimum Detectable Change (MDC).