Heroin assessment in Spanish population-based studies: a scoping review

Estimating the prevalence of use of substances such as heroin remains a challenge. The aim of this study is to identify the scientific publications in Spain that have used surveys to investigate heroin use, to describe their methodology and to contrast the formulation of the questions with users' input on key aspects associated with use.

A scoping review was conducted until November 2024 in MEDLINE (Ovid), EMBASE and Web of Science. The review included questionnaire-based research studies assessing heroin use in Spain. Information on study, population, data collection and consumption characteristics was compiled from each included study. In addition, in-depth interviews were conducted with Spanish heroin current users and ex-users.

Twenty-nine questionnaire-based research studies assessing heroin use in Spain were identified; none of them were specifically oriented to estimate and characterise heroin use at the population level. Most of the studies focused on specific population groups, mainly drug users, students, or inmates. The majority addressed lifetime, past-year, and past-month use, although users found the past 3 or 6 months more relevant. Few studies explored other use characteristics; however, interviews with heroin ex-users highlighted the importance of factors like route of administration and age of first use.

The studies identified in this review vary in terms of target population, geographic scope, reference time frame, and data collection methods. Moreover, questionnaires rarely address additional characteristics of use that are considered relevant by former users. This review identifies areas for improvement to guide future studies and refine methodological approaches.