Edinburgh Napier University

  Background
Novel psychoactive substances (NPS) are new narcotic or psychotropic drugs that are not controlled by the United Nations drug convention that may pose a serious public health threat due to their wide availability for purchase on the internet and in so called “head shops.” Yet, the extent of their global use remains largely unknown. The aim of this study is to conduct a systematic review of the prevalence of NPS use in non-clinical populations.

Methods
This is a systematic review of observational studies. Embase, MEDLINE, PubMed, Cumulative Index to Nursing and Allied Health (CINAHL), Cochrane Library, Lilacs, Scopus, Global Health, PsychINFO, Web of Science, and the World Health Organization (WHO) regional databases will be searched for eligible prevalence studies published between 2010 and 2016. Data from cross-sectional studies that report the prevalence of NPS use (one or more types) in participants (of any age) from censuses or probabilistic or convenience samples will be included. Data will be extracted from eligible publications, using a data extraction tool developed for this study. Visual and statistical approaches will be adopted instead of traditional meta-analytic approaches.

Discussion
This review will describe the distributions of various types of prevalence estimates of NPS use and explore the impact of different population groups and study-related and tempo-geographical variables on characteristics of these distributions over the period of 2010 to 2016.

Systematic review registration
PROSPERO CRD42016037020