Prevalence and related factors of symptom-based sexually transmitted infections among men who inject drugs: findings from three nation-wide surveys in Iran, 2010-2023.

BACKGROUND

Sexually transmitted infections (STI) are a major public health concern and can increase HIV acquisition and transmission risk. People who inject drugs (PWID) may have elevated vulnerability due to overlapping sexual, injection-related and structural risk environments.

OBJECTIVE

To estimate the prevalence of symptom-based STI among PWID in 2010, 2014 and 2023 and explore factors associated with STI symptom reporting among men who inject drugs (MWID) in 2023.

DESIGN

Exploratory analysis of three repeated cross-sectional national bio-behavioural surveillance surveys.

SETTING

Major Iranian cities.

PARTICIPANTS

PWID aged ≥18 years who had injected in the past 12 months, resided in the study city and provided informed consent. Facility/outreach recruitment was used in 2010/2014, and respondent-driven sampling (RDS) was used in 2023.

PRIMARY OUTCOME: Self-reported pain/burning, genital ulcers, discharge or genital warts in the past 12 months defined symptom-based STI reporting. Data were collected by structured face-to-face interviews, followed by HIV testing.

RESULTS

Symptom-based STI prevalence among PWID was stable (2010: 10.1%; 2014: 10.5%; 2023: 10.3%). Among MWID in 2023, prevalence was 8.8% (95% CI 7.26 to 10.57). STI symptom reporting was associated with HIV and Hepatitis C Virus positivity. In exploratory multivariable analysis, STI symptom reporting was associated with being separated/widowed/divorced (AOR 2.56; 95% CI 1.14 to 5.7), multiple sexual partners (AOR 4.08; 95% CI 1.22 to 13.65), unprotected sex with casual partners (AOR 2.41; 95% CI 1.27 to 4.58), ever experienced sex with men (AOR 2.98; 95% CI 1.36 to 6.54), stimulant injection (AOR 2.57; 95% CI 1.08 to 6.14) and sharing injection equipment (AOR 2.84; 95% CI 1.53 to 5.27).

CONCLUSION

Symptom-based STI remain persistent among PWID in Iran. Findings highlight the importance of supporting integrated STI prevention, testing, condom provision, syndromic management and linkage to care within harm reduction services to improve STI control among PWID. Associations should be interpreted as hypothesis-generating, not causal.