Remarks y The term “drug use disorders”, “cannabis use disorders”, “stimulant use disorders”, “opioid use disorders” refers to diagnosis according to the ICD-10 or DSM-IV criteria or equivalent ICD-11 and DSM-5 diagnosis. y By the term “any drug use”, we refer to studies recruiting participants who use at least one psychoactive drug and are included in interventions targeting substance use reduction regardless of the primary drug. y The included digital interventions encompass unguided digital interventions, in which psychoeducation and psychotherapeutic techniques are provided for the individual to self-manage their symptoms without the help of a health worker. In guided digital interventions, additional guidance is provided to assist participants with technical or health-related questions via chat, email or telephone. y Studies that assess the reduction of any drug use via digital interventions compared with non-active comparators are usually recruiting individuals from settings in which brief interventions are conducted. These settings commonly include hospitals, primary care clinics and community health centres. The majority of those interventions consist of very brief screenings and brief interventions lasting up to 30 minutes. y The studies assessing the reduction of drug use via digital interventions compared with active comparators are usually recruiting individuals from specialized treatment facilities. The majority of those interventions combine the digital component with face-to-face treatments, such as TAU or CBT, and last 8–12 weeks. y Differences in findings between active/non-active comparators should be interpreted with caution. For the comparisons involving non-active comparators, the majority of individuals were recruited based on self-reported use patterns and not assessed for a substance use disorder. This is contrary to the studies involving active comparators that recruited participants after the diagnosis of a substance use disorder. For this reason, it is important to stress that different findings for active/non-active comparators are likely due to the different characteristics (such as severity) of the target group and intensity of the provided treatment. y While the evidence is limited, it is possible that individuals with a substance use disorder who receive TAU in addition to a digital intervention benefit more from the digital component. This is particularly relevant for individuals with drug use disorders. y While digital health interventions show effectiveness and can enhance access to health services, they should not be used to replace or detract from provision of other forms of interventions and should ensure patients’ free and informed consent, safety, confidentiality, privacy and security. y Any treatment or support for people using drugs or with drug use disorders should ensure ethical standards – including respect for human rights and the individual’s dignity, and never using humiliating or degrading interventions – in line with the WHO and UNODC International standards for the treatment of drug use disorders (147) (see Box 3.1).

Implementation considerations y Digital interventions can provide benefits to people using drugs and with drug use disorders, especially when provided in addition to TAU. They should not substitute provision of other types of conventional treatment (psychosocial or pharmacological) to people with drug use disorders. When face-to-face treatment is not available or acceptable, self-help digital interventions can be a feasible option to provide support. y There are concerns regarding potentially sensitive content and data privacy while using digital health interventions. Measures should be taken ensuring that digital interventions are provided under conditions of safety/security, confidentiality, informed consent and privacy of data. This can include the establishment of standard operating procedures that describe protocols for ensuring patient consent, data protection and storage, and verifying provider licensing and credentials. Further guidance can be found in the 2019 WHO guideline: recommendations on digital interventions for health system strengthening (31). y There might be an issue with potential digital divide across population groups having unequal access to and skills to use digital technologies. Access might be particularly difficult for certain population groups with poor access to network services, mobile devices or electricity, and/or with low literacy and digital literacy skills. Measures should be taken to address inequities in access to mobile devices so that further inequity is not perpetuated in accessing health information and services, including mechanisms to ensure individuals who do not have access to mobile devices can still receive appropriate services. y Country adaptation and translation of digital interventions tools is essential.