Development and psychometric validation of a questionnaire assessing perception and acceptance of micronutrient-fortified bouillon cubes among non-index household members aged ≥ 15 years in northern Ghana

Background: Micronutrient deficiencies remain a major public health issue in West Africa, contributing to anaemia, impaired cognitive development, and increased infection risk. Bouillon cubes, widely consumed in the region, offer a culturally appropriate means of micronutrient delivery. However, no validated instrument exists to assess the psychosocial and behavioural factors influencing household acceptance of fortified bouillon cubes. This study aimed to develop and validate a questionnaire to assess perceptions and acceptance of micronutrient-fortified bouillon cubes among non-index household members (NIHMs) in northern Ghana. Methods: A 29-item questionnaire was developed based on the Theory of Planned Behaviour and the Health Belief Model. Development involved a literature review, expert consultation, and pretesting with 18 adults. The instrument included 26 five-point Likert-scale items and 3 categorical items. One NIHM (i.e., household members aged ≥ 15 years who were not enrolled as primary trial participants) was randomly selected per household using the Kish method. The questionnaire was administered to 742 NIHMs within 1–2 months of intervention initiation in a double-blind randomised controlled trial comparing multiple micronutrient-fortified versus iodine-only bouillon cubes in Kumbungu and Tolon districts. Of these, 731 NIHMs were retained for analysis, with the dataset divided into exploratory (n = 292) and confirmatory (n = 439) factor analyses. Psychometric properties were evaluated using Cronbach’s alpha, composite reliability (CR), and average variance extracted (AVE). Results: Participants (mean age = 40.8 ± 17.4 years) were 58.8% female, 74.8% without formal education, and 38.4% were the primary household cooks. Exploratory factor analysis identified two constructs, Perception (8 items) and Acceptance (11 items), explaining 56% of variance. Confirmatory factor analysis retained 18 items (Perception = 8; Acceptance = 10) and showed good model fit (chi-square/df = 1.91, root mean square error of approximation [RMSEA] = 0.04, comparative fit index [CFI] = 0.98, Tucker–Lewis index [TLI] = 0.98, and standardized root mean square residual [SRMR] = 0.06). Internal consistency was acceptable (Cronbach’s alpha: Perception = 0.71; Acceptance = 0.72; CR = 0.86 and 0.82, respectively). AVE was 0.52 for Perception and 0.46 for Acceptance. Discriminant validity was supported. Conclusion: The validated 18-item questionnaire shows acceptable psychometric properties and offers a standardised tool for assessing household perception and acceptance of fortified foods, suitable for programme design, evaluation, and behavioural monitoring in bouillon-consuming settings.