Psychometric validation of a knowledge questionnaire on micronutrients among adolescents and its relationship to micronutrient status of 15–19-year-old adolescent boys, Hyderabad, India

摘要

Abstract Objective To develop a psychometrically valid questionnaire for testing knowledge on micronutrients and to assess the relationship between knowledge and biomarkers of micronutrient status among adolescents. Design Cross-sectional, institution-based, validity and reliability study. Setting Seven higher secondary schools were covered in the limits of Greater Hyderabad Municipal Corporation, Hyderabad, India. Subjects Students aged 15a€“19 years, n 92 for the pre-test, n 108 for testa€“retest and n 109 for studying the relationship between knowledge and biomarkers of Fe, retinol, ascorbic acid, ?±-tocopherol, folic acid and vitamin B12 status. Results From an item pool of 106, thirty-one items were selected based on content validity. Statistical tools to obtain a valid and reliable questionnaire among adolescent boys and girls resulted in eighteen items with a difficulty index of 0?·11a€“0?·86, discrimination index of 0?·20a€“0?·72 and validity index (point bi-serial correlation) of 0?·10a€“0?·62. Reliability as measured by Cronbach's ?± was 0?·71 and the intra-class correlation coefficient was 0?·80. A Blanda€“Altman plot showed good agreement between test and retest scores. The mean response score to the eighteen-item questionnaire was 5?·2 (sd 2?·68). The mean values of serum retinol were significantly different (P = 0?·022) between groups below (24?·8 (sd 6?·64) ??g/dl) and above (28?·0 (sd 7?·67) ??g/dl) the 50th percentile of knowledge score. The relationship persisted after controlling for economic status as a covariate using analysis of covariance (P = 0?·018). Other micronutrients did not show any significant relationship. Conclusions A valid and reliable eighteen-item knowledge questionnaire was constructed and found to have a significant positive relationship with plasma retinol status alone.