Development and Validation of a Questionnaire to Predict Intention to Comply to Iron Supplement during Pregnancy

Introduction: The World Health Organisation (WHO) has recommended iron supplementation to overcome anaemia in pregnancy. In Malaysia, half of pregnant women with anaemia do not comply to iron supplement. The purpose of this study is to develop, assess psychometric properties (via Exploratory Factor Analysis) and validation (via Confirmatory Factor Analysis) of a questionnaire that evaluates attitude towards adherence to iron supplement based on Theory of Planned Behaviour (TPB). Methods: Based on the guidelines for construction of the TPB based questionnaire, 18 items were created initially by using the findings from a semi-quantitative survey, literature reviews and experts’ opinion. From content validity by 3 experts, 15 items with content validity ratio (CVR) of ≥0.99 were retained. From a pilot test for exploratory factor analysis (EFA), total of 12 items were retained, and classified into 3 components and termed as “Attitude”, “Subjective Norms” and “Perceived Behaviour Control”. Results: Cronbach Alpha for the 12 items was 0.814, and for each component were 0.844, 0.813 and 0.901 respectively, which indicates acceptable internal consistency. During the Confirmatory Factor Analysis (CFA), a final 10 items were retained. Conclusions: The construct validity was good where the Fitness Index have achieved the threshold (p-value 0.05, RMSEA 0.08, CFI 0.90 and the ChiSq/df ratio 3.00). The convergent validity and composite reliability were good i.e. Average Variance Extracted (AVE) ≥0.50, and Composite Reliability (CR) ≥0.60 respectively. As a conclusion, this newly developed questionnaire was validated and potentially reliable in assessing attitude and predicting adherence to iron supplement among pregnant women specifically in Malaysia.