Research Article: Polydrug Use and Heterogeneity in HIV Risk Among People Who Inject Drugs in Estonia and Russia: A Latent Class Analysis

Date Published: July 11, 2017

Publisher: Springer US

Author(s): Isabel Tavitian-Exley, Marie-Claude Boily, Robert Heimer, Anneli Uusküla, Olga Levina, Mathieu Maheu-Giroux.


Non-medical drug injection is a major risk factor for HIV infection in Russia and Estonia. Multiple drug use (polydrug) has further been associated with increased harms. We compared HIV, injecting and sexual risk associated with polydrug use among people who injected drugs (PWID) in 2012–2013 in Kohtla-Järve (Estonia, n = 591) and St Petersburg (Russia, n = 811). Using latent class analysis, we identified five (poly)drug classes, the largest consisting of single-drug injectors among whom an opioid was the sole drug injected (56% of PWID). The four remaining polydrug classes included polydrug-polyroute injectors who injected and used opiates and stimulants (9%), opiate-stimulant poly-injectors who injected amphetamine-type-stimulants with a primary opiate (7%) and opiate-opioid poly-injectors who injected opioids and opiates (16%). Non-injection stimulant co-users were injectors who also used non-injection stimulants (12%). In multivariable multinomial regressions, all four polydrug classes were associated with greater injection risks than single-drug injection, while opiate-stimulant and opiate-opioid poly-injection were also associated with having multiple sex partners. Riskier behaviours among polydrug-injectors suggest increased potential for transmission of blood-borne and sexually-transmitted infections. In addition to needles/syringes provision, services tailored to PWID drug and risk profiles, could consider drug-appropriate treatment and sexual risk reduction strategies to curb HIV transmission.

Partial Text

Non-medical drug injection has been a driver of HIV and hepatitis C (HCV) epidemics in Eastern Europe and central Asia, where people who inject drugs (PWID) were estimated to account for half of new HIV and a majority of HCV infections in 2014 [1–5]. Estonia and Russia in particular have reported some of the highest HIV prevalence in key populations–populations disproportionately affected by HIV—outside of sub-Saharan Africa [1, 6–11]. HIV sero-positivity among PWID was 53% in Tallinn, the capital of Estonia, and 70% in Kohtla-Järve, the fifth largest city in the country in 2007 [12–14]. In the Russian Federation, HIV prevalence ranged from 9% to 64% among PWID and was 59% among PWID in St Petersburg in 2009 [15, 16].

Our study included 1402 active PWID who had injected drugs in the previous 4 weeks, were 18 years or older and lived in Kohtla-Järve (n = 591) or St Petersburg (n = 811). Sample characteristics were previously described [10, 16, 45–47] and are summarised in Table S1. RDS recruitment measures are shown in Table S2. Most PWID were male (76%), of Russian ethnicity (90%), had completed basic education (i.e. up to 9th grade) (68%) and injected for over 5 years (93%). Almost half had a non-regular income (47%) and 38% were under 30 years old. Past month contact with an NSP was 43% with more PWID reporting contact in Kohtla-Järve than in St Petersburg (Table S1).

Our study found that polydrug use was substantial among PWID in Kohtla-Järve and St Petersburg, 44% of whom belonged to one of four polydrug classes. It also uncovered considerable differences in HIV risk behaviours with significantly greater injecting and sexual risk among polydrug than single-drug injectors (Table 4). Despite non-significant differences in HIV and HCV prevalence, riskier behaviours found among polydrug injectors suggest increased potential for continuing transmission of blood borne and sexually transmitted infections. Among polydrug classes, polydrug-polyroute injectors engaged in more frequent injecting and sharing risk behaviours than exclusive injectors. However, opiate-stimulant poly-injectors and opiate-opioid poly-injectors both reported more injecting and sexual risk behaviours than single drug injectors, with opiate-opioid poly-injectors also reporting sex partners who injected drugs. Non-injection stimulant co-users differed less from single-drug injectors but were more likely to back-load syringes and have had sex in the last six months (Table 4).Table 4Summary of associations between demographic, injecting and sexual risk behaviours and latent poly(drug) use classes as compared to single drug injectorsClass 1 Polydrug polyroute injectionClass 2 Opiate-stimulant poly-injectionClass 3 Non-injection stimulant co-useClass 4 Opiate-opioid poly-injection–↑ <30 years old↑ <30 years old↑ <30 years old↑ non- Russian ethnicity––↑ non- Russian ethnicity––↓ Secondary education–––↑ Non-regular income–––––↑ Kohtla-Järve–↑ Kohtla-Järve↑ St Petersburg↑ Frequent injecting↑ Frequent injecting–=Frequent injecting↑ Intense injecting↑ Intense injecting–↑ Intense injecting↑ Shared needles/syringes↑ Shared needles/syringes–↑ Shared needles/syringes↑ Sharing paraphernalia↑ Sharing paraphernalia––↑ Back-loaded↑ Back-loaded↑ Back-loaded––↑ Any sex last 6 months↑ Any sex last 6 months––↑ Multiple sex partners–↑ Multiple sex partners–––↑ Regular sex partner injects–––↑ Casual sex partner injects“↑and ↓” indicate positive and negative associations, respectively. “=” positive direction but non-significant association   Source:


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