The filter of choice: filtration method preference among injecting drug users

BACKGROUND: Injection drug use syringe filters (IDUSF) are designed to prevent several complications related to the injection of drugs. Due to their small pore size, their use can reduce the solution's insoluble particle content and thus diminish the prevalence of phlebitis, talcosis.... Their low drug retention discourages from filter reuse and sharing and can thus prevent viral and microbial infections. In France, drug users have access to sterile cotton filters for 15 years and to an IDUSF (the Sterifilt(®)) for 5 years. This study was set up to explore the factors influencing filter preference amongst injecting drug users. METHODS: Quantitative and qualitative data were gathered through 241 questionnaires and the participation of 23 people in focus groups. RESULTS: Factors found to significantly influence filter preference were duration and frequency of injecting drug use, the type of drugs injected and subculture. Furthermore, IDU's rationale for the preference of one type of filter over others was explored. It was found that filter preference depends on perceived health benefits (reduced harms, prevention of vein damage, protection of injection sites), drug retention (low retention: better high, protective mechanism against the reuse of filters; high retention: filter reuse as a protective mechanism against withdrawal), technical and practical issues (filter clogging, ease of use, time needed to prepare an injection) and believes (the conviction that a clear solution contains less active compound). CONCLUSION: It was concluded that the factors influencing filter preference are in favour of change; a shift towards the use of more efficient filters can be made through increased availability, information and demonstrations.