Development process and psychometric testing of foot health assessment instrument

Aims and objectives To describe the development process of the foot health assessment instrument for the assessment of foot health in older people and to evaluate the psychometric properties of the foot health assessment instrument. Background In clinical nursing, assessment of foot health and recognition of foot problems in older people is fundamental for maintain older persons' independent functional ability. However, valid and reliable nurse-administered foot health assessment instruments are lacking. Design A cross-sectional methodological design. Methods The foot health assessment instrument was developed in 20082011 based on a literature review and expertise in podiatry and nursing. Content validity was evaluated in four expert panels. Inter-rater reliability between nurses' and researcher (MS) assessments was evaluated in the pilot test and in the empirical testing of the instrument with a sample of visiting home nurses. Inter-rater reliability was calculated with Cohen's kappa, internal consistency reliability was examined with Cronbach's alpha coefficients and item analysis, and construct validity was evaluated by principal component analysis with Varimax rotation and confirmatory factor analysis. Results Content validity was guaranteed by the expert analyses. Inter-rater reliability improved after pilot test. The Cronbach's alpha coefficient for the total foot health assessment instrument was satisfactory. Item-to-total correlations varied between but most of them were acceptable. Principal component analysis and confirmatory factor analysis supported the four component structure of the foot health assessment instrument. Conclusions The 23-item foot health assessment instrument showed preliminary acceptable psychometric properties. However, further modifications and testing are needed to strengthen the psychometric properties of the foot health assessment instrument. Relevance to clinical practice The existence of a foot health assessment instrument and its application would considerably improve the assessment of foot health in daily nursing practice. The foot health assessment instrument developed in this study is short and easy to administer.