Safe sex norm questionnaire for female sex workers: development and validation study in Iran

The aim of the present study was to develop and validate a safe sex norm questionnaire as an appropriate instrument which would be adaptable to the female sex worker (FSW) population. A mixed method study. Appropriate content was prepared through a literature review. Content validation indices were assessed using interviews with content experts and lay experts. A conservative approach was used to assess the inter-rater agreement among the participants about the instrument relevance and clarity. The scale content validity index was computed using the average method. Non-parametric Mokken scale analysis was used for assessing scalability and unidimensionality of the questionnaire in a sample of 170 FSWs in Tehran. To evaluate the reliability and internal consistency of the questionnaire intra-class correlation and Cronbach's alpha were employed. A list of 34 items was finalized, with subscales for actual behavioral norms and for perceived norms. The relevance of the actual and perceived norms subscales in the final questionnaire was higher than 96%; clarity of the subtests was 99% and higher. The comprehensiveness of the actual and perceived norms subscales was 85% for both. Mokken scale analysis showed that the two subscales were distinct constructs, and all items are good indicators for the constructs. Our findings support that the safe sex norm questionnaire is a valid and reliable measure that would be useful to harm reduction programs and help effective HIV prevention among female sex workers. •A content valid and reliable questionnaire was developed to evaluate safe sex norm in female sex workers (FSWs).•The Safe Sex Norm Questionnaire (SSNQ) composed of two subscales, actual and perceived norms.•The SSNQ would be useful for application in harm reduction programs and may help effective HIV prevention among FSWs.•SSNQ could be used in other contexts with similar populations; however, for such purposes it may need contextual adaptation.