One of the most accepted footedness measure outcomes is the Waterloo Footedness Question-Revised (WFQ-R). The main advantage of WFQ-R against the other questionnaires of the same category is that it has been designed to assess both foot preference for mobilizing and stabilizing tasks. Therefore, it has been used in an extensive number of neurophysiology research and motor behavior research protocols.
Purpose: The purpose of this study is to translate and present the psychometric properties of the Greek version of WFQ-R in healthy people using translation protocols consistent with internationally recognised guidelines.
Methods: For the cross-cultural adaptation, the back-translation procedure was utilised, comprising forward and backward translations by 4 bi-lingual translators. In pilot study, questionnaire was completed from 30 healthy subjects for linguistic validation and understanding.
For the reliability testing, 278 subjects completed twice the questionnaire (140 females and 139 males, 35.9 ± 12.5 years old). The test-retest reliability was estimated as the degree of concordance between repeated administrations of WFQ-R (total scale – WFQ-Rt, mobility subscale – WFQ-Rm and stability subscale – WFQ-Rs) between the two weeks period of time whereas internal consistency was estimated as the extent to which items in each questionnaire's subscales (WFQ-Rm and WFQ-Rs) were correlated, thus measuring the same concept. For the validity testing, 86 subjects participated (40 females and 46 males, 22.7 ± 3.6 years old). Participants additionally performed four functional single leg hop tests. The degree of lateralisation was calculated using the logarithm of the odds ratio (log odds ratio) between the right (R) and left (L) lower limb performance: λ = ln(right limb score/left limb score). Concurrent validity was assessed by comparing the two WFQ-R subscales and construct validity by comparing the WFQ-R with the four different degrees of lateralisation given from the functional tests.
All data were tested for normal distribution using Kolmogorov–Smirnov test and accordingly, parametric or non-parametric tests were used. Spearman's correlations (rho) and Wilcoxon signed rank test was used for differences in questionnaire responses between the two weeks (test–retest reliability), Pearson's (r) correlation was used for concurrent validity and Cronbach's alpha (α) was used to estimate the internal consistency of the component grouped footedness tasks (mobility and stability items) by examining the average inter-item correlations, using the Statistical Package for the Social Sciences (SPSS, version 20.0).
Results: The distribution of the WFQ-R scale and subscales had no serious ceiling and floor effects. The results of the internal consistency calculations for both the mobility and stability items produced a high alpha value of 0.827 and 0.820 respectively. The Spearman correlation coefficient showed good correlation between the test–retest measurements for all three scales and both genders (p < 0.01). Results support moderate construct validity.
Conclusion(s): The Greek version of the WFQ-R has proven to be valid, reliable, comprehensible and acceptable for the Greek population tested.
Implications: The Greek version of WFQ-R is a valid and reliable tool for the assessment of footedness and could be used with confidence from researchers and clinicians assessing Greek-speaking population both healthy and patients.