Developing and testing of an interactive internet-based intervention to reduce sexual harm of sexualised drug use ('chemsex') among men who have sex with men in Hong Kong: a study protocol for a randomised controlled trial

Background: Sexualised drug use, known as 'chemsex' or 'chemfun,' is the practice of intentionally using illicit drugs before or during sexual activates to enhance sexual arousal and pleasure. International and local data have both suggested that chemsex is common among men who have sex with men (MSM). Chemsex is generally seen with the engagement of risky sexual activities and therefore poses a threat regarding the potentially increased spread of human immunodeficiency virus and other sexually transmitted infections. However, little work has been done on the primary prevention of chemsex among MSM. Therefore, the aim of this study is to develop and evaluate an interactive internet-based intervention in reducing the sexual harms of chemsex among MSM in Hong Kong, METHODS: A two-armed, randomised, parallel-group trial with a three-month follow-up period will be conducted. 250 MSM aged 18 years or the above will be recruited through local non-governmental organisations, social media and by snowballing in Hong Kong. Participants will be randomly allocated into either the intervention (n = 125) or control group (n = 125). The interactive internet-based intervention will be developed based on the theory of planned behaviours. Participants in the control group will receive a web-based intervention without any sexual health information and without any interactive components. The primary outcomes will be self-efficacy in refusing risky sexual behaviours and chemsex, as measured by the Drug Avoidance Self-Efficacy Scale, the Self-Efficacy for Sexual Safety and the Condom Self-Efficacy Scale. Subjects in both groups will be evaluated at baseline and 3 months after baseline.

Discussion: To the best of our knowledge, this will be the first interactive internet-based intervention to specifically target chemsex among MSM. This project can help in the development and testing of culturally relevant health promotion programmes that reduce chemsex among MSM. Using an online delivery mode, the intervention is capable of reaching a large population of targets at a relatively low cost and thus has the potential to reduce the public health burden of chemsex and other risky sexual behaviours among MSM in a cost-effective manner.

Trial registration: International standard randomized controlled trial number (ISRCTN) registry: ISRCTN20134522 registered on 17 March 2021.