Prevalence and risk factors for khat use among youth students in Ethiopia: systematic review and meta-analysis, 2018

Background Khat use is a widely spreading public health problem affecting the most economically productive population areas in Ethiopia. Khat use among students has been linked with mental, physical, social, and psychological problems. Reliable prevalence has not been recognized because of varying published rates. The objective of this systematic review and meta-analysis is to synthesize evidence on the prevalence and potential risk factors of khat use in Ethiopia. Methods We found 284 studies of which 266 were removed due to duplication, irrelevant topics, and other reasons, respectively. All studies conducted in Ethiopia on khat chewing among students irrespective of time frame were included. Subsequently, 18 studies were used for synthesis of prevalence. Figures were extracted from published reports, and any lost information was requested from investigators. The quality of the included literature was evaluated by using the Newcastle–Ottawa Scale (NOS). Prevalence was pooled using random-effects meta-analyses. The presence of association was declared using P-values and an odds ratio with a corresponding 95% CI. Results The pooled prevalence of khat use among students was 16.7% (13.7–19.7%). In the subgroup analysis, the highest prevalence was observed in the Oromia region, at 21.1% (15.5%, 26.7%), and an almost equal prevalence of 14.8% (10.6, 18.9) and 14.3% (10.3, 18.3) was observed in Amhara and the Southern Nation, Nationalities, and People’s Region of Ethiopia, respectively. Being male (OR: 2.43 (1.73, 3.13)), being a Muslim religion follower (OR: 2.22 (1.6, 2.8)), being an alcohol user (OR: 2.3 (1.5, 3.0)), khat use by a family member (OR: 1.8 (1.4, 2.2)), peer pressure (OR: 4.4 (3.1, 5.6)), and being a cigarette smoker (OR: 8.5 (5.3, 11.7)) were found to be risk factors for khat chewing. Conclusions Khat use is a common problem among students. Health promotion, awareness on effect of khat, set policy on khat and substance use on the male sex, Muslim religion, alcohol user, having a family-member khat user, peer pressure, and being a cigarette smoker as possible risk factors for khat use among students. Limitations Irrespective of time restriction, all studies conducted in Ethiopia are included and cross-sectional in nature. Protocol no. CRD-42017081886.

Khat has a stimulant effect on the body [5,6]. The fresh green leaves and young buds are chewed [7]. This stimulates both the peripheral and vital nervous system, causing, for instance, insomnia, alertness, anorexia, and increased respiration, body temperature, blood pressure, and heart rate [8]. The stimulant effect is mutually enhanced by caffeine use and cigarette smoking [9]. Khat use has appeared to be a male habit, but women practise it as well [10]. Users start chewing at an early age and develop an uncontrollable habit lasting throughout the lifespan [11]. It is practised based on local customs and traditions [12] and carried out in religious ceremonies [13,14].
Khat chewing is a familiar habit among students for staying alert, achieving higher concentration at work, socializing, and providing relaxation, relief from stress, and a desire to study for long hours [34][35][36][37].
Moreover, being male, having chewer friend(s), believing that chewing khat will boost performance, drinking alcohol, and having a family that cultivates khat were found to considerably increase the chewing practice [34,[38][39][40].
The literature includes studies conducted in Ethiopia among students. However, the literature shows a difference in prevalence and associated factors. Therefore, this systematic review and meta-analysis aim to estimate the pooled prevalence and associated factors of current use of khat chewing among students in Ethiopia.

Methods
PubMed/MEDLINE, Scopus, HINARI and EMBASE were searched for published studies. In addition, 10 pages were accessed using Google Scholar. All references in the relevant articles were reviewed in order to obtain other studies. Furthermore, for partial articles or those missing necessary information, the authors of the articles were contacted via email or other means of communication. For the PubMed search, the following terms were applied: 'khat chewing' , 'khat use' , 'chewing habit' , 'determinant factors*' , 'student' , 'college students' and 'Ethiopia' . An advanced search was conducted using these terms with the options 'MeSH terms' and 'all fields' selected and including ' AND' and 'OR' Boolean operators as appropriate. The rest of the electronic databases were searched using database-specific subject headings linked with the terms and keywords used in PubMed. "Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)" guidelines used [41]. To show the procedures used for the screening and selection processes, a PRISMA flow diagram was used. The findings of this meta-analysis are presented here in with the aid of figures.

Review and meta-analysis registration
This systematic review and meta-analysis were registered at the International Prospective Register of Systematic Reviews. The following represents the registration number: CRD-42017081886.

Eligibility criteria
Three investigators (WG, TA and WW) independently screened the selected articles using their titles and abstracts before retrieving the full-text papers. We use pre-specified inclusion criteria to screen the full-text articles. Disagreements between the investigators were discussed during a consensus meeting with a fourth reviewer (SS) in order to select the studies to be included in the systematic review and meta-analysis.

Inclusion criteria
• Cross-sectional studies. • Studies on khat chewing among students. • Studies published in English. • Studies reporting on the prevalence and/or determinants of khat chewing. • Studies conducted in Ethiopia.

Exclusion criteria
• Editorials, letters, reviews, commentaries and interventional studies. • Studies without access to the full data even after contacting the author(s). • Duplicate studies.

Data extraction
All the articles accessed using the databases and search engines were exported to EndNote (version 6), and we excluded duplicate articles. The remaining articles were evaluated based on the topic, language and study area. Next, studies conducted outside of Ethiopia, those not published in English and those on irrelevant topics were excluded. There were no time restrictions among the included studies. Finally, the abstracts and full text of the remaining articles were reviewed.

Outcome variable
Current khat use is defined as the proportion of students who are chewing for different purposes within 3 months of prior to data collection.

Data synthesis and quality assessment
After extracting and documenting the data in a Microsoft Excel spreadsheet, we exported it to Stata (version 14) for further analysis. All the analyses were conducted using Comprehensive Meta analysis software (version 3) [42]. The overall pooled prevalence of khat chewing was estimated using a random-effects meta-analysis [43]. First, using a fixed-effects model, heterogeneity among the studies was determined. A Q test and an I 2 heterogeneity test [43] were used to declare heterogeneity at p < 0.05. The prevalence of statistical heterogeneity between the studies was assessed using I 2 statistics, with 25%, 50% and 75% representing low, medium and high heterogeneity, respectively [44]. The quality of the included studies was evaluated using the Newcastle-Ottawa Scale [45] and tested based on sample size and representativeness, comparability between participants, ascertainment of khat chewing and statistical quality. To test the agreement between the three reviewers, the actual agreement and agreement beyond chance (unweighted kappa) were used. The values of reviewers' result 0, 0.01-0.20, 0.21-0.40, 0.41-0.60, 0.61-0.80, and 0.81-1.00 were used to represent poor, slight, fair, moderate, substantial, and almost perfect agreements, respectively [46]. A randomeffects model was used in the analysis. Meta-regression was conducted to explore the probable source of heterogeneity. A leave-one-out sensitivity analysis was also conducted to assess which studies majorly impacted between-study heterogeneity. A funnel plot and Egger's regression test were used to measure publication bias.

Search outcomes
The systematic literature search generated a total of 284 articles. In total, 55 were duplicated and 167 were irrelevant, and, as such, these were excluded. In addition, 44 were excluded (not measure outcome, measure not current use). The remaining 18 articles were used to determine the pooled prevalence of khat chewing in Ethiopia. All 18 articles were cross-sectional studies (Fig. 1).
All the included studies were conducted in Ethiopia (Table 1). Finally, the levels of agreements between the reviewers about the levels of bias for studies included in this meta-analysis we got from moderate to almost perfect (Kappa statistic range 0.60-1) ( Table 2).

Publication bias
There was no evidence of bias, as observed in the funnel plot. An Egger's regression test confirmed this (p = 0.53) (Fig. 5).

Factors associated with khat use
Khat use is common among high school, college and university students. There are many risk factors, but just we include those reported in more than one study. Being male is more likely to chew khat than females (OR: 2.43 (1.73, 3.13). In addition, khat chewing is predominantly practised by Muslims (OR: 2.22 (1.6, 2.8). Students with a family member who had a history of khat use or who currently uses khat are more likely to chew khat than students without such a family member (OR: 1.8 (1.4, 2.2).

Discussion
The objectives of this systematic review and meta-analysis were to assess the prevalence and associated factors of khat use among young students in Ethiopia. Young students who are habitual khat users believe that its use boosts alertness, concentration, imaginative abilities, and improves communication skills. To the best of our knowledge, this systematic review and meta-analysis is the first of its kind, assessing the pooled prevalence and factors that have an effect on the habitual use of khat among young students in Ethiopia. The overall pooled prevalence of khat use was found to be 16 ure-3). Clearly illustrated above, the subgroup analysis demonstrated that the pooled prevalence of khat use among young students is slightly different across different regions of Ethiopia. The possible reason for these variations could be environmental, religious, and/or cultural differences across the regions. For example, people residing in the Oromia region are Muslim followers. In addition to this, the higher prevalence of khat chewing in this region could be explained by the differences in settings across regions, such as access to khat and factors outside the university and high school environment.
A meta-analysis study previously completed on University students found that 23.22% (95% CI 19.5, 27.0%) of these students were chewers, which is a bit higher than our findings [43]. This discrepancy might be due to differences in study population, while ours considered young students on high school and university, the former one focused on university students, these students couldn't afford to buy the khat and they might not use.
Multiple factors have contributed to young students to be khat users. Being male, younger age, religion, ethnicity, khat use by family, family history of other substances use, living condition, peer pressure, other psychoactive substance use, having a family that cultivates khat, perceive khat use boosts performance, increased class workload, residency, having suicidal ideation, having ever had a sexual contact were found to be the most important associated factors.
Gender of students continued to be a significant factor affecting students' behaviour. Being male sex had a significant role to be user as compared to females. This finding is line with studies conducted in Ethiopia [2,36,[47][48][49][50][51]. This significant difference between male and female may be justified as; females are less exposed to chewing  practice than males. Moreover, we found that being Muslim by religion had a significant role to be user than others [2,36,41,43,51,52].
Having chewer friends was strong predictor of chewing which is similar to other studies [2,41,43,45,49,50,53], khat use by family member was associated with increased odds of use among participants. This finding was similar with studies conducted on substance abuse [2,36,48,49]. The possible cause for the association may be because of shared influence and peer pressure.
Furthermore, in this review, it has been observed that other substance use is common among study participants. Who had ever drunk alcohol and ever smoked cigarette were more likely to practise chewing as compared to no alcohol and cigarette users. This finding is supported by r studies conducted, ever drunk alcohol [52,54], and smoking cigarette [43,48,50,52,54]. These studies reported that history of alcohol consumptions and cigarette smoking was positively associated with chewing. This finding provides evidence on the prevalence of khat use on Ethiopian students with relevant data. Measures to reduce the use of khat should be taken and these should be considered as priority areas: awareness, family contribution, prevention and early intervention.

Conclusions
Khat use is prevalent among high school, college and university students. The prevalence of khat use appeared to be high. Particular attention should be given to male gender, Muslims religion follower, alcohol users, having family member khat user, peer pressure, being cigarette smoker. There is a need for early intervention that targets high school, college, and university students to reduce the health, financial and social consequences of khat use.

Limitations of the study
The limitation was that only English articles were considered to conduct this review. In addition, all of the studies included in this review were cross-sectional  Table 2 The quality and agreed level of bias and level of agreement on the methodological qualities of included studies in a meta-analysis based on sampling, outcome, response rate and method of analysis