Fluid Intake Appraisal Inventory: Development and psychometric evaluation of a situation-specific measure for haemodialysis patients' self-efficacy to low fluid intake

ObjectiveSelf-efficacy is an important determinant of health behaviour and reflects a person's belief about their capability to complete a given task. The relationship between self-efficacy and fluid adherence has been investigated, although limited attention has been given to measurement issues. The purpose of this study was to develop a measure of situation-specific self-efficacy for constructive fluid intake behaviour in haemodialysis patients, the Fluid Intake Appraisal Inventory (FIAI).MethodsItems were generated from an analysis of empirical studies available in the literature and exposed to an interpretability critique before haemodialysis patients confirmed sufficiency of each item. In a multi-centre study, data from 144 haemodialysis patients were collected regarding general self-efficacy, situation-specific self-efficacy, and estimated fluid consumption. Internal consistency, criterion-related validity, and structural validity were tested.ResultsThe FIAI was found to have high internal consistency (Cronbach alpha 0.96) and the theoretical assumptions for criterion-related validity and known-group validity were supported. Structural validity was not confirmed, however, because the theoretically hypothesized four-factor model was not the prime structure.ConclusionThe FIAI was revealed to have satisfactory psychometric properties. The scale may be used in research or in clinical settings to study the mediating effects of self-efficacy or to modify haemodialysis patients' fluid-intake behaviour. Although this first validity study is promising, further validation focusing on reliability and cultural validity is needed.