Testing for amphetamine-type stimulant (ATS) use to ascertain validity of self-reported ATS use among young female sex workers in Cambodia

Vannda Kab,Kimberly Page,Lisa Maher,Ellen Stein,Marie Claude-Couture,Neth Sansothy,Jennifer Evans

doi:10.1186/1940-0640-7-11

Abstract

ObjectiveTo assess concordance between self-reported amphetamine-type stimulant (ATS) use and toxicology results among young female sex workers (FSW) in Phnom Penh, Cambodia.MethodsCross-sectional data from the Young Women’s Health Study-2 (YWHS-2), a prospective study of HIV and ATS use among young (15 to 29 years) FSW in Phnom Penh, Cambodia, was analyzed. The YWHS-2 assessed sociodemographic characteristics, HIV serology, HIV risk, and ATS use by self-report and urine toxicology testing at each quarterly visit, the second of which provided data for this assessment. Outcomes include sensitivity, specificity, positive- and negative predictive values (overall and stratified by age), sex-work setting, and HIV status.ResultsAmong 200 women, prevalence of positive toxicology screening for ATS use was 14% (95% confidence interval [CI], 9.2, 18.9%) and concurrent prevalence of self-reported ATS was 15.5% (95% CI, 10.4, 20.6%). The sensitivity and specificity of self-reported ATS use compared to positive toxicology test results was 89.3% (25/28), and 96.5% (166/172), respectively. The positive predictive value of self-reported ATS use was 80.6% (25/31); the negative predictive value was 98.2% (166/169). Some differences in concordance between self-report and urine toxicology results were noted in analyses stratified by age group and sex-work setting but not by HIV status.ConclusionResults indicate a high prevalence of ATS use among FSW in Phnom Penh, Cambodia, and high concordance between self-reported and toxicology-test confirmed ATS use.

Highlights

Cambodia has the highest HIV prevalence of any Asian country, and over the last decade has experienced the most serious HIV/AIDS epidemic in Southeast Asia [1]
The Young Women’s Health Study-2 (YWHS-2) was led by HIV-research and HIV-prevention specialists from the Cambodian National Center for HIV, AIDS, Dermatology, and STDs (NCHADS), the Cambodian Women’s Development Association (CWDA), the University of California San Francisco (UCSF) in the United States, and the Kirby Center at the University of New South Wales (UNSW) in Australia
Positive predictive value of self-report Among 31 women who reported using amphetamine-type stimulant (ATS) use within the last 48 hours, 80.6% had positive urine toxicology tests

Summary

Introduction

Cambodia has the highest HIV prevalence of any Asian country, and over the last decade has experienced the most serious HIV/AIDS epidemic in Southeast Asia [1]. Amphetamine-type stimulants include a range of synthetic psychostimulants, including methamphetamine, amphetamine, and ecstasy, which can be injected, smoked, or taken orally. Effects of these drugs include euphoria, alertness, arousal, increased libido, increased sympathetic nervous responses, (heart rate, respiratory rate, blood pressure), and perceived increases in confidence, energy and physical strength [11]. In Cambodia, ATS are highly available both in pill and crystalline form and are generally ingested or smoked; injection use is uncommon [21]. The drug accounts for the majority of all drug seizures by authorities, and, in pill form, has been ranked as the leading drug of abuse for the past nine years with consistent increases since 2006 [20], at which time it was estimated that 30,000 tablets of yama were consumed orally or smoked there daily. Use is high among vulnerable populations, including FSW [3,9], men who have sex with men (MSM), and street children [12,20,21]

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Conclusion