Mental Disorders Associated with Khat Use: A Scoping Review and Meta- Analysis

Abstract

Background: Khat is the substance mainly used for its central nervous stimulation effects. The substance has been associated with several mental health problems, and there is an ongoing international concern about this causal relationship. Nevertheless, an effort to scope and systematically review mental health effects of khat based on the available studies is a much- ignored venture. Objective: The objective of the study is to map, summarize and pool effect size of the association between khat use and mental disorders Methods: The study has two phases. The first phase deals with the scoping review of the association between khat and mental disorders using PubMed, SCOPUS, Embase and CINAHL databases to map and clarify the existing published studies on the relationship between khat use and mental disorders. The second phase is a meta-analysis of the association between khat use and ‘non-specific psychological distress’ identified using scoping review as having rich evidence to warrant meta-analysis. Newcastle Ottawa Scale (NOS) is used to assess the qualities of studies used for meta-analysis. The meta-analysis employed RevMan version 5.4.1 and Comprehensive meta-analysis (CMA) software. Heterogeneity among estimates is quantitatively evaluated with the I 2 -statistic. The Hedges method of pooling odds ratios is plotted using forest plots and pooled odds ratio (OR) is calculated. Publication bias is investigated by construction of funnel plots and Egger’s test. Results: The initial online search of the four databases yielded a total of 7,121 articles and the search of gray literature produced 5 eligible articles. A total of N=108 are considered eligible for the scoping review. The studies are conducted in 12 different countries, a dramatic increase in the number of studies was observed only during the last ten years and the studies mostly employed cross-sectional design. Khat use is mostly measured using a single item ‘yes/no’ question and attention to study the ‘dose-dependent effect’ of khat use on mental health is not given much attention. About 14 different categories of mental disorders and related conditions have been identified as having association with khat use. The meta-analysis shows that the pooled effect size of psychological distress among people who use khat in the form of odds ratio (OR) using Trim and Fill the imputed point estimate is 2.09 (1.56, 2.78), as compared to those who don’t use khat. Conclusion: Although most of the studies associated khat use with mental disorder, the development of conclusive evidence about cause-effect relation is impossible given the cross- sectional design dominating most of the studies, contradictory findings and the limited number of studies employing advanced designs.