RESUMEN
BACKGROUND: The average age of using illicit drugs for the first time in adolescents has decreased in Iran over the past years. Studies show that family and environment play a notable role in keeping adolescents away from substances. AIMS: The present study is an attempt to develop and validate a model-based questionnaire to measure parental factors related to substance use prevention in adolescents. METHODS: This methodological study was carried out on 336 parents of high school students in Sabzevar- Iran, in 2018. The first draft of the questionnaire, including 136 items, was developed based on the constructs of the Health Promotion Model (HPM) using similar questionnaires, literature review, and interviewing 9 qualified experts. The validity of the questionnaire was measured through face validity (qualitative and quantitative), content validity (qualitative and quantitative), and construct validity (confirmatory factor analysis). The reliability of the questionnaire was measured by internal consistency and test-retest reliability. SPSS ver. 16 and LISREL ver. 8.2 software was used for statistical analysis. RESULTS: Throughout the validation process, 35 items were omitted, and the final version of the questionnaire consisting of 101 items was developed. The overall content validity ratio was 0.81, which indicates the proper and understandable content of the items. The overall content validity index was 0.96, which indicates excellent expert validity. The Cronbach's alpha coefficient of the questionnaire was 0.85 (constructs range= 0.73-0.96), and the intraclass correlation coefficient of the questionnaire was 0.78 (constructs range= 0.46-0.91), which indicates that the questionnaire has good internal consistency and test-retest reliability. Further, the confirmatory factor analysis yielded an appropriate fit for the model (RMSEA= 0.069, χ2/df= 2.77, GFI= 0.60, AGFI= 0.83, CFI= 0.83, NNFI= 0.83). CONCLUSION: The validity and reliability of the HPM-based questionnaire were supported. Therefore, the questionnaire can be used by health educators and health policymakers in empowerment programs for parents to improve their behavioral skills concerning the prevention of substance use in their adolescents.