Filipino Translation and Cross-cultural Adaptation of the Diabetic Foot Knowledge Subscale (DFKS) and Foot Self-Care Behavior Scale (FSCBS) and its Content Validation and Reliability Testing

Abstract

Background. Type 2 diabetes is the most common type of diabetes in the Philippines. Diabetic foot complications represent a prevalent and significant chronic concern for individuals with type 2 diabetes. This poses an immediate community health concern, as diabetic complications may threaten an individual's well-being.

Objective. This study intends to cross-culturally adapt the Diabetic Foot Knowledge Subscale (DFKS) and Foot Self-Care Behavior Scale (FSCBS) questionnaires into the Filipino language as an assessment tool among Filipinos with diabetes.

Methods. The study employed a psychometric research design, where it entailed Phase A and Phase B. Phase A involved the forward translation of the DFKS and FSCBS questionnaires, followed by the synthesis of the translations and backward translation. Subsequently, an expert committee reviewed the translations and concluded the final version. The final translated versions of the questionnaires ensured that it can be understood by an individual who has a Grade 6 level of reading proficiency. Phase B entailed the validity testing with the evaluation of the expert committee, and reliability testing of the said questionnaires with a sample size of 30 participants. A wash-out period of 24 hours was given for the test-retest reliability, followed by data analysis. The validity and reliability of the questionnaires were measured using the item and scale content validity indices and the internal consistency and test-retest reliability, respectively, to ensure their accuracy and appropriateness. The content validity of the questionnaires was evaluated individually by the experts using a Likert scale from 1-4, with 4 being the highest meaning the item was very relevant and succinct. Scores per item were between 3 and 4, which indicate that the translated version of the items were relevant and succinct or were relevant but needed minor revisions.

Results. The validity scores for the translated DFKS and FSCBS questionnaires were obtained using the Scale Content Validity Index (S-CVI) with a score of 0.96 and 0.92, respectively. Moreover, all items in the questionnaires obtained an Item Content Validity Index (I-CVI) of 0.88-1.00. The DFKS also has an acceptable internal consistency with a Cronbach’s alpha of 0.72, while the FSCBS has a good internal consistency with a Cronbach’s alpha of 0.85. The test-retest reliability shows an acceptable Spearman’s correlation at 0.76 for the DFKS and a strong positive Pearson correlation coefficient at 0.73 for the FSCBS.

Conclusion. The validity of the two questionnaires was acceptable and the test-retest reliability showed a strong positive correlation among the items thereby making the cross-cultural adaptation of the questionnaires successful. The Filipino versions of the DFKS and FSCBS questionnaires accurately measure the knowledge and behavior of individuals with type 2 diabetes, respectively.