This investigation into the psychometric qualities of the Arabic version of the FHSQ, conducted at a single center, followed its initial translation and cross-cultural adaptation for patients with plantar fasciitis. The FHSQ score is a tool that developed to evaluate the effect of foot surgery.9,13 It can also assess foot disorders and overall quality of life. It's the best tool for assessing Plantar Fasciitis and is important for patients to have a valid assessment across different cultures.14 To achieve this, the FHSQ should be available in many languages, including Arabic for cross-cultural comparison.
The translation followed translation and back translation method with a native Arabic speakers.17,18 The overall structure and format of the questionnaire was maintained during all stages of the translation and adaptation process. Agreement regarding the appropriate translation of phrases like "How often" was reached during the initial translation steps. Upon the completion of the translation process, we conducted a pre-test version of the Arabic FHSQ on 30 patients. The initial evaluation phase demonstrated that patients had a very good understanding of all questions, comments regarding inappropriate Likert scales was deemed and corrected with further 20 patients added to confirm the clarity of the newly edited Likert scales.
Foot Function domain was highest affected domain among our population while physical activity is the least one (70.5, 34.6 respectively). These results were lower than general population of Saudi Arabia as expected and in line with a study conducted in a population of PF patient.
Following the completion of the cross-cultural adaptation process, we proceeded to evaluate the Arabic version of the FHSQ in our patient population. This paper included considerations such as dimensionality, internal consistency, reproducibility (encapsulating both reliability and agreement), interpretability, and construct validity. The Principal Component Analysis (PCA) executed in our study brought forward a four-factor solution, accounting for a significant proportion of variance. Although this was somewhat inferior to the initial investigation,13 it rendered a satisfactory level of internal consistency, as well as indication of construct validity.
Internal consistency is a metric that quantifies the degree of correlation between items within a domain of a questionnaire, essentially signifying that they measure the same construct and exhibit homogeneity.25 The original investigation reported an internal consistency in the range of 0.851 to 0.884.13 However, the FHSQ-Ar demonstrated a Cronbach's alpha > 0.90 across all domains, except the Footwear domain which still showcased a good internal consistency of 0.70.
The Arabic adaptation of the FHSQ exhibited satisfactory reproducibility, presented through the calculated reliability and agreement. The reproducibility of a test refers to how consistent the results are when the same test is repeated multiple times on the same individuals under stable conditions. Reliability was assessed using ICCagreement, with the Footwear domain scoring the lowest (0.69) and the GFH domain scoring the highest (0.80). This concurs with the original authors' findings where the Footwear domain scored the lowest, a pattern that echoes in other transcultural adaptations of the FHSQ.13,34
Agreement was computed via the standard error of measurement (SEm) and the subsequent smallest detectable change (SDC) at both individual and group levels. Our analysis revealed SEm values ranging from 11.8 to 13.5 across the different FHSQ sub-scales, with Footwear and Foot Function domains yielding the lowest and highest SEms, respectively. The resulting SDC(individual) values for each domain varied from 32.7 to 37.4 at the individual level, implying that a change of at least 32.7 points in the Footwear domain or 37.4 points in the Foot Function domain can be discerned as a true change rather than a measurement error. These results suggest that the translated and validated FHSQ may not be optimal for application at the individual level due to the high SDC values. However, SEm and SDC were not calculated in the original study for comparison, although they were computed in the Dutch transcultural adaptation of the FHSQ which yielded analogous results.13,34 The calculated SDC(group) in this study ranged between 5.1 in Footwear to 5.8 in Foot Function domain, indicating that the FHSQ-Ar is suitable for conduction at the group level. The Minimal detectable change (MID) of the FHSQ is estimated to vary from − 0.3 to 13 across scales.35
The validity of the four-factor model was corroborated by their associations with the VAS0-100mm score. All four hypotheses were fulfilled. The Footwear domain wasn't anticipated to show a correlation since this domain gauges a construct hypothesized to be independent from heel pain intensity as per the original instrument.13 The fit indices associated with the CFA models were satisfactory for the FHSQ-Ar.
Limitations of this study include reliance on an internet-based survey, curtailing the feasibility of retesting patients under identical circumstances—a less than ideal scenario for evaluating reliability and measurement error.36 Furthermore, many respondents declined to be engaged in an online survey for a lack of trust contributing to a response rate that was below the desired numbers. Additionally, our sampled population may not accurately mirror the demographic suffering from plantar fasciitis in Saudi Arabia as there's an absence of comprehensive sociodemographic data for the region. The strengthes of this study includes the methodological assessments of the translation procedure and the inclusion of various psychometric properties aligned with standard guidelines. Adhering to these guidelines bolsters the credibility of our questionnaire's application. Lastly, though we've rendered the FHSQ into Arabic, its applicability needs further validation across other conditions, not limited to Plantar Fasciitis, in subsequent researches.