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Studying complex interactions among determinants of healthcare-seeking behaviours: self-medication for sexually transmitted infection symptoms in female sex workers
  1. Gabriela B Gomez1,
  2. Pablo E Campos2,
  3. Clara Buendia2,
  4. Cesar P Carcamo2,
  5. Patricia J Garcia2,
  6. Patricia Segura3,
  7. William L Whittington4,
  8. James P Hughes5,
  9. Helen Ward1,
  10. Geoffrey P Garnett1,
  11. King K Holmes4,6,7
  1. 1Department of Infectious Disease Epidemiology, Imperial College London, London, UK
  2. 2Epidemiology, STI and HIV/AIDS Unit, Universidad Peruana Cayetano Heredia, Lima, Perú
  3. 3INMENSA, Lima, Perú
  4. 4Department of Medicine, University of Washington, Seattle, Washington, USA
  5. 5Department of Biostatistics, University of Washington, Seattle, Washington, USA
  6. 6Centre for AIDS and STD, Seattle, Washington, USA
  7. 7Department of Global Health, University of Washington, Seattle, Washington, USA
  1. Correspondence to Dr Gabriela B Gomez, Institute for Global Health, Imperial College London, South Kensington Campus, 15 Prince's Gardens, London SW7 1NA, UK; g.gomez{at}


Objectives To describe the frequency and determinants of self-medication for symptoms of sexually transmitted infections (STI) in a female sex worker (FSW) population. To present a methodology exploring the best predictors as well as the interactions between determinants of self-medication.

Methods A cross-sectional survey of 4153 FSW carried out in Peru. The prevalence of self-medication was estimated from the subsample of participants who had experienced symptoms of STI in the past 12 months (n=1601), and used successive logistic regression models to explore the determinants.

Results Self-medication prevalence for a reported symptomatic episode during the past 12 months was 32.1% (95% CI 29.8 to 34.6). It was negatively correlated with work in brothels (adjusted odds ratio (OR) 0.51, 95% CI 0.28 to 0.93; p=0.028) and awareness of STI services available for FSW (adjusted OR 0.49, 95% CI 0.29 to 0.81; p=0.006). Other determinants were organised at different levels of proximity to the outcome creating pathways leading to self-medication.

Conclusions The importance of the staggered analysis presented in this study resides in its potential to improve the understanding of associations between determinants and, consequently, the targeting of interventions. The awareness of STI services available for FSW increases access to health care, which in turn decreases self-medication. In addition, the sharing of information that takes place between brothel-based FSW was also related to a diminishing prevalence of self-medication. These two main predictors provide an opportunity for prevention programmes, in particular those designed to be led by peers.

  • Epidemiology
  • female sex worker
  • Peru
  • prostitution
  • self-medication
  • self-treatment
  • sexually transmitted infections
  • social epidemiology

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  • Funding The PREVEN study is funded by the Wellcome Trust Foundation, (#GR-078835), National Institutes of Health CIPRA (#AI-053218) and NIH/NIAID UW STI/Topical Microbicide Cooperative Research Center (#AI-031448). GBG was funded by the Medical Research Council, UK.

  • Competing interests HW is co-editor of the journal Sexually Transmitted Infections. All other authors declare no conflicts of interest.

  • Patient consent Obtained.

  • Ethics approval The PREVEN study obtained ethics approval from institutional review boards at the Universidad Peruana Cayetano Heredia, the University of Washington in Seattle and the US Navy Medical Research Center Detachment in Lima, which has been renewed every year.

  • Provenance and peer review Not commissioned; externally peer reviewed.