Background People who use drugs (PWUD) are considered as one of the main at-risk populations for Hepatitis B virus (HBV) infection. We conducted a systematic review on the prevalence of HBV infection among PWUD in Iran. Methods Consistent with PRISMA guideline, international (Medline, Web of Science, Scopus, and Embase) and national (Scientific Information Database) databases were searched using a comprehensive search strategy up to September 2019. The retrieved records were reviewed, and experts were contacted for unpublished studies. Studies on Iranian PWUD reporting HBV surface Antigen (HBsAg) prevalence among people who inject drugs (PWID) and non-injecting PWUD were included. HBsAg prevalence was pooled for PWID and non-injecting PWUD and for other subgroups using random-effects model meta-analysis. The trend of HBV prevalence over time was investigated using meta-regression analysis. Results Overall, 35 studies reported data on HBV infection among PWID (33 studies) and non-injecting PWUD (11 studies). The pooled prevalence of HBsAg among PWID was 4.8% (95% CI 3.7–6.2). The only risk factor significantly associated with the odds of positive HBsAg in PWID was the previous history of imprisonment (OR 1.72, 95% CI 1.29–2.30, p value = 0.000). The pooled estimate of HBsAg among non-injecting PWUD was 2.9% (95% CI 2.5–3.2). Time trend analyses showed significant decrease in HBV prevalence among PWID reaching from 8.2% (95% CI 3.9–16.5) in 2004–2006 to 3.1% (95% CI 2.3–4.1) in 2016 and later (b = -0.07; p value = 0.05). No significant trend was detected for non-injecting PWUD. Conclusion The prevalence of HBV infection among non-injecting PWUD and even PWID was not considerably higher than the Iranian general population. This might be the result of extensive harm reduction interventions in Iran. However, it seems that there are subgroups of PWID, who do not adequately benefit from existing harm reduction interventions. Future programs should more specifically target these high-risk groups.

Background and aims Cannabis is the most widely used illicit substance globally. In this systematic review, we examined the prevalence and trends of cannabis use and cannabis use disorder in Iran. Methods We searched International and Iranian databases up to March 2021. Pooled prevalence of use among sex subgroups of the general population, university and high school students, combined youth groups, and high-risk groups was estimated through random-effects model. Trends of various use indicators and national seizures were examined. Results Ninety studies were included. The prevalence estimates of last 12-month cannabis use were 1.3% (95%CI: 0.1–3.6) and 0.2% (95%CI: 0.1–0.3) among the male and female Iranian general population, respectively. The prevalence of cannabis use disorder among general population in national studies rose from 0% in 2001 to 0.5% in 2011. In the 2016–2020 period, the pooled prevalence estimates of last 12-month cannabis use were 4.9% (95% CI: 3.4–6.7) and 0.3% (95% CI: 0.0–1.3) among males and females of “combined youth groups”, respectively. The linear trend of last 12-month cannabis use among males of "combined youth groups" and among female university students increased significantly from 2000 to 2020. Conclusions Prevalence of cannabis use in Iran is low compared to many countries. However, there is strong evidence of an increase in cannabis use among the youth and some evidence for an increase in cannabis use disorder.

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