The street cost of drugs and drug use patterns: relationships with sex work income in an urban Canadian setting

BACKGROUND

This study investigated the relationship between drug use and sex work patterns and sex work income earned among street-based female sex workers (FSWs) in Vancouver, Canada.

METHODS

We used data from a sample of 129 FSWs who used drugs in a prospective cohort (2007-2008), for a total of 210 observations. Bivariate and multivariable linear regression using generalized estimating equations was used to model the relationship between explanatory factors and sex work income. Sex work income was log-transformed to account for skewed data.

RESULTS

The median age of the sample at first visit was 37 years (interquartile range[IQR]: 30-43), with 46.5% identifying as Caucasian, 48.1% as Aboriginal and 5.4% as another visible minority. The median weekly sex work income and amount spent on drugs was $300 (IQR=$100-$560) and $400 (IQR=$150-$780), respectively. In multivariable analysis, for a 10% increase in money spent on drugs, sex work income increased by 1.9% (coeff: 0.20, 95% CIs: 0.04-0.36). FSWs who injected heroin, FSWs with higher numbers of clients and youth compared to older women (<25 versus 25+ years) also had significantly higher sex work income.

CONCLUSIONS

This study highlights the important role that drug use plays in contributing to increased dependency on sex work for income among street-based FSWs in an urban Canadian setting, including a positive dose-response relationship between money spent on drugs and sex work income. These findings indicate a crucial need to scale up access and availability of evidence-based harm reduction and treatment approaches, including policy reforms, improved social support and economic choice for vulnerable women.

Severe food insecurity is associated with elevated unprotected sex among HIV-seropositive injection drug users independent of HAART use

OBJECTIVE

Despite emerging evidence of a significant adverse relationship between food insecurity and sexual risk-taking, data have been primarily derived from resource-constrained settings and HIV-negative populations. To our knowledge, this study is the first to longitudinally evaluate the relationship between food insecurity and unprotected sex among HIV-seropositive people who inject drugs [injection drug users (IDUs)] both on and not on HAART.

DESIGN

Longitudinal analyses were restricted to HIV-positive IDUs who completed baseline and at least one follow-up visit in a prospective cohort (AIDS Care Cohort to evaluate Exposure to Survival Services, 2005-2009).

METHODS

We constructed a multivariate logistic model using generalized estimating equations (GEEs) to assess an independent relationship between severe food insecurity (e.g., hunger due to lack of access or means to acquire food) and unprotected vaginal/anal sex.

RESULTS

Among 470 HIV-positive IDUs, the median age was 42 years (interquartile range 36-47) with 61% men and 39% women. The prevalence of severe food insecurity was 71%, with no differences by HAART use. Severe food insecure IDUs were marginally less likely to have a suppressed HIV-1 RNA viral load (31 vs. 39%, P = 0.099). In multivariate GEE analyses, severe food insecurity [adjusted odds ratio = 2.68, 95% confidence interval 1.49-4.82] remained independently correlated with unprotected sex among HIV-positive IDUs, controlling for age, sex/gender, married/cohabitating partner, binge drug use, homelessness, and HAART use.

CONCLUSION

These findings highlight a crucial need for structural HIV interventions that incorporate targeted food assistance strategies for IDUs. Given recent evidence of poor virological response among food insecure individuals on HAART, innovative HIV care models should integrate targeted food security programs and early access to HAART.

Crystal methamphetamine use among female street-based sex workers: Moving beyond individual-focused interventions

Given growing concern of the sexual risks associated with crystal methamphetamine use and the dearth of research characterizing the use of methamphetamine among street-based sex workers (FSWs), this study aimed to characterize the prevalence and individual, social, and structural contexts of crystal methamphetamine use among FSWs in a Canadian setting. Drawing on data from a prospective cohort, we constructed multivariate logistic models to examine independent correlates of crystal methamphetamine among FSWs over a two-year follow-up period using generalized estimating equations. Of a total of 255 street-based FSWs, 78 (32%) reported lifetime crystal methamphetamine use and 24% used crystal methamphetamine during the two-year follow-up period, with no significant associations between methamphetamine use and sexual risk patterns. In a final multivariate GEE model, FSWs who used crystal methamphetamine had a higher proportional odds of dual heroin injection (adjOR=2.98, 95%CI: 1.35-5.22), having a primary male sex partner who procures drugs for them (adjOR=1.79, 95%CI: 1.02-3.14), and working (adjOR=1.62, 95%CI: 1.04-2.65) and living (adjOR=1.41, 95%CI: 1.07-1.99) in marginalized public spaces. The findings highlight the crucial need to move beyond the individual to gender-focused safer environment interventions that mediate the physical and social risk environment of crystal methamphetamine use among FSWs.

Prevalence and structural correlates of gender based violence among a prospective cohort of female sex workers

OBJECTIVE

To examine the prevalence and structural correlates of gender based violence against female sex workers in an environment of criminalised prostitution.

DESIGN

Prospective observational study.

SETTING

Vancouver, Canada during 2006-8.

PARTICIPANTS

Female sex workers 14 years of age or older (inclusive of transgender women) who used illicit drugs (excluding marijuana) and engaged in street level sex work.

MAIN OUTCOME MEASURE

Self reported gender based violence.

RESULTS

Of 267 female sex workers invited to participate, 251 women returned to the study office and consented to participate (response rate of 94%). Analyses were based on 237 female sex workers who completed a baseline visit and at least one follow-up visit. Of these 237 female sex workers, 57% experienced gender based violence over an 18 month follow-up period. In multivariate models adjusted for individual and interpersonal risk practices, the following structural factors were independently correlated with violence against female sex workers: homelessness (adjusted odds ratio for physical violence (aOR(physicalviolence)) 2.14, 95% confidence interval 1.34 to 3.43; adjusted odds ratio for rape (aOR(rape)) 1.73, 1.09 to 3.12); inability to access drug treatment (adjusted odds ratio for client violence (aOR(clientviolence)) 2.13, 1.26 to 3.62; aOR(physicalviolence) 1.96, 1.03 to 3.43); servicing clients in cars or public spaces (aOR(clientviolence) 1.50, 1.08 to 2.57); prior assault by police (aOR(clientviolence) 3.45, 1.98 to 6.02; aOR(rape) 2.61, 1.32 to 5.16); confiscation of drug use paraphernalia by police without arrest (aOR(physicalviolence) 1.50, 1.02 to 2.41); and moving working areas away from main streets owing to policing (aOR(clientviolence) 2.13, 1.26 to 3.62).

CONCLUSIONS

Our results demonstrate an alarming prevalence of gender based violence against female sex workers. The structural factors of criminalisation, homelessness, and poor availability of drug treatment independently correlated with gender based violence against street based female sex workers. Socio-legal policy reforms, improved access to housing and drug treatment, and scale up of violence prevention efforts, including police-sex worker partnerships, will be crucial to stemming violence against female sex workers.

High rates of homelessness among a cohort of street-involved youth

Using multivariate logistic regression, we examined the prevalence and correlates of homelessness among youth enrolled in a community-recruited prospective cohort known as the At-Risk Youth Study (ARYS), between September 2005 and October 2006. Of 478 individuals included in this analysis, 132 (27.6%) were female and 120 (25.1%) self-identified as Aboriginal. The median age was 22 (IQR: 20-24). In total, 284 (56.9%) participants reported baseline homelessness, with most living either at no fixed address, on the street, or in a hostel or shelter. Factors associated with homelessness included public injecting, frequent crack use, experienced violence, having less than a high-school education, and not having been in any addiction treatment. Homeless individuals were at-risk for various adverse health outcomes. These findings indicate the need for additional interventions, including residential addiction treatment, to address homelessness and drug use among youth.

CD4-dependent characteristics of coreceptor use and HIV type 1 V3 sequence in a large population of therapy-naive individuals

We investigated the associations between coreceptor use, V3 loop sequence, and CD4 count in a cross-sectional analysis of a large cohort of chronically HIV-infected, treatment-naive patients. HIV coreceptor usage was determined in the last pretherapy plasma sample for 977 individuals initiating HAART in British Columbia, Canada using the Monogram Trofile Tropism assay. Relative light unit (RLU) readouts from the Trofile assay, as well as HIV V3 loop sequence data, were examined as a function of baseline CD4 cell count for 953 (97%) samples with both phenotype and genotype data available. Median CCR5 RLUs were high for both R5 and X4-capable samples, while CXCR4 RLUs were orders of magnitude lower for X4 samples (p < 0.001). CCR5 RLUs in R5 samples (N = 799) increased with decreasing CD4 count (p < 0.001), but did not vary with plasma viral load (pVL) (p = 0.74). In X4 samples (N = 178), CCR5 RLUs decreased with decreasing CD4 count (p = 0.046) and decreasing pVL (p = 0.097), while CXCR4 RLUs increased with decreasing pVL (p = 0.0008) but did not vary with CD4 (p = 0.96). RLUs varied with the presence of substitutions at V3 loop positions 11, 25, and 6-8. The prevalence and impact of substitutions at codons 25 and 6-8 were CD4 dependent as was the presence of amino acid mixtures in the V3; substitutions at position 11 were CD4 independent. Assay RLU measures predictably vary with both immunological and virological parameters. The ability to predict X4 virus using genotypic determinants at positions 25 and 6-8 of the V3 loop is CD4 dependent, while position 11 appears to be CD4 independent.

HIV VprR77Q mutation does not influence clinical response of individuals initiating highly active antiretroviral therapy

VprR77Q has been associated with long-term nonprogressive (LTNP) HIV infection. We wished to investigate the prevalence, clinical correlates, and effect on treatment response of VprR77Q in a cohort of antiretroviral- naïve individuals initiating highly active antiretroviral therapy (HAART). Baseline plasma samples from 728 subjects were genotyped using RT-PCR and direct DNA sequencing. Cox proportional hazards regression was used to model the effects of VprR77Q on virologic and immunologic responses, and survival following initiation of HAART, over a median 4.5 years follow-up. We found that 308 subjects (42.3%) harbored VprR77Q alone or in combination with another amino acid, while 420 (57.7%) harbored an amino acid other than Q. A cross-sectional analysis found no correlation between R77Q and baseline plasma viral load (pVL), CD4 count, diagnosis of AIDS, or sociodemographic characteristics including age, gender, and history of injection drug use (p > 0.1). In multivariate analyses, no significant associations between VprR77Q and initial pVL and CD4 responses to HAART or survival following initiation of treatment were observed (p > 0.1). The high prevalence and the lack of association with pretherapy clinical parameters in this cohort argue against an association of R77Q with LTNP status. These results do not support an association between R77Q and HAART response.

Antiretroviral effect of two different dose regimens of ritonavir and saquinavir on HIV-infected adults in a population-based setting

OBJECTIVE

To characterize the antiviral effect and tolerability of higher dose (HD, 600 mg two times daily) and lower dose (LD, 400 mg two times daily) combination regimens of ritonavir and saquinavir in British Columbia (BC), Canada.

DESIGN

Intent-to-treat analysis with suppression of plasma viral load to levels below 500 copies/ml as the main outcome measure.

PATIENTS

Adult human immunodeficiency virus (HIV)-positive individuals in the province of British Columbia prescribed ritonavir and saquinavir in combination between 1 September 1996 and 30 June 1997, with a minimum of two plasma viral loads, one at baseline and one after the initiation of therapy.

RESULTS

A total of 84 participants [27 HD (32%) and 57 LD (68%)] were prescribed ritonavir and saquinavir. There was no difference at baseline in the two groups with respect to age (P=0.466), CD4 cell count (P=0.373) and baseline plasma viral load (P=0.656). However, LD were more likely to have had prior protease experience than HD participants (65 versus 40%, P=0.037). The median follow-up time was 9 months. A total of 44 (52%) subjects demonstrated a decrease in plasma viral load to levels <500 copies/ml. After adjusting for length of follow-up, baseline CD4 cell count and prior AIDS diagnosis, HD participants were as likely to be suppressed to <500 copies/ml as LD individuals (P=0.760). HD participants did report more adverse effects (P=0.042) than LD subjects.

CONCLUSION

Our results provide confirmatory evidence that lower doses of ritonavir and saquinavir in combination are better tolerated and as effective as the standard doses of these drugs. This response, however, is seriously compromised by prior exposure to protease inhibitors.

Discrepant results in the interpretation of HIV-1 drug-resistance genotypic data among widely used algorithms

OBJECTIVES

The aim of this study was to assess the concordance on the interpretation of HIV-1 drug-resistance genotypic data by three widely used algorithms: Stanford University Database (SU), TruGene (Visible Genetics, Canada) (VG) and VirtualPhenotype (Virco, Belgium) (VP).

METHODS

Genotypic data from 293 HIV-1-infected individuals with treatment failure was interpreted for 14 antiretroviral drugs by the three algorithms.

RESULTS

Complete concordant results among the three systems for all the drugs studied were found in 40/293 (13.7%) samples. Low concordance in the interpretation was observed for most nucleoside reverse transcriptase inhibitors (NRTIs), while results agreed highly for all nonnucleoside reverse transcriptase inhibitors (NNRTIs) and most protease inhibitors (PIs). In pair-wise comparisons, discordant interpretations between SU and VP were found in over 50% of the samples for didanosine, zalcitabine, stavudine and abacavir, and the level of disagreement between VG and VP exceeded 40% for the same drugs. Major discrepancies (high-level resistance interpretation by one algorithm with sensitive interpretation by another) were observed between VG and VP in over 10% of the cases for didanosine, zalcitabine, stavudine and abacavir. On the other hand, the three algorithms had concordant results for lamivudine in over 90% of the cases.

CONCLUSIONS

This work demonstrates the great level of discordance in the interpretation of genotyping results among algorithms, clearly showing the necessity for clinical validation. Moreover, these results suggest that a joint effort from the scientific community as well as national and international HIV societies is needed to achieve a consensus for the interpretation of genotypic data.

Management of HIV-infected Patients with Multidrug-resistant Virus

Heavily pretreated HIV-infected patients with multidrug-resistant virus remain a clinical challenge to the treating physician. While the goal of therapy in such patients is still controversial, sustained immunologic and clinical benefit have only been demonstrated with complete suppression of plasma viral load below detectable levels. Expert use of resistance testing may help in the selection of the salvage regimen, and monitoring of plasma drug levels may help optimize the potency and tolerability, especially of complex, multiple drug regimens where adherence remains a critical determinant of treatment outcome. The potential roles of newer agents, adjuvants, treatment interruptions, and immune-based therapies remain under investigation.

Symptomatic elevations of lactic acid and their response to treatment manipulation in human immunodeficiency virus-infected persons: a case series

Symptomatic lactic acidemia was seen in 5 human immunodeficiency virus-positive patients receiving combination therapy that included stavudine and > or =1 other nucleoside. Peak venous lactic acid levels of 3.1-7.4 mmol/L (normal range, 0.5-2.1 mmol/L) were associated with fatigue and rapid weight loss, whereas withdrawal of antiretrovirals led to normalization of venous lactic acid levels, symptomatic improvement, and weight gain. Resumption of an altered therapeutic regimen, which did not include stavudine but did include other nucleosides in 4 of 5 cases, did not result in recurrence of the syndrome after up to 126 days.

Industry-sponsored clinical research: a double-edged sword

Drug development has accelerated exponentially since the 1950s. It is difficult to estimate the relative contributions or rates of success of industry sponsored as opposed to government supported research in any field. However, it is clear that much of the therapeutic innovation of recent decades has emerged from biotechnology and pharmaceutical industry sponsored efforts. This sponsorship is leading to new stresses in the relationship between academic institutions and industry.

Rates of disease progression by baseline CD4 cell count and viral load after initiating triple-drug therapy

CONTEXT

Current recommendations for initiation of antiretroviral therapy in patients infected with human immunodeficiency virus type 1 (HIV) are based on CD4 T-lymphocyte cell counts and plasma HIV RNA levels. The relative prognostic value of each marker following initiation of therapy has not been fully characterized.

OBJECTIVE

To describe rates of disease progression to death and AIDS or death among patients starting triple-drug antiretroviral therapy, stratified by baseline CD4 cell count and HIV RNA levels.

DESIGN, SETTING, AND PARTICIPANTS

Population-based analysis of 1219 antiretroviral therapy-naive HIV-positive men and women aged 18 years or older in British Columbia who initiated triple-drug therapy between August 1, 1996, and September 30, 1999.

MAIN OUTCOME MEASURE

Cumulative mortality rates from the initiation of triple-drug antiretroviral therapy to September 30, 2000, determined using various CD4 cell and plasma HIV RNA thresholds.

RESULTS

As of September 30, 2000, 82 patients had died of AIDS-related causes, for a crude AIDS-related mortality rate of 6.7%. The product limit estimate (SE) of the cumulative mortality rate at 12 months was 2.9% (0.5%). In univariate analyses, a prior diagnosis of acquired immunodeficiency syndrome (AIDS), CD4 cell count, use of protease inhibitors, and HIV RNA level were associated with mortality. There was no difference in mortality by age or sex. Only CD4 cell count remained statistically significant in the multivariate analysis. After controlling for AIDS, protease inhibitor use, and plasma HIV RNA level at baseline, patients with CD4 cell counts of less than 50/microL were 6.67 (95% confidence interval [CI], 3.61-12.34) times and those with counts of 50/microL to 199/microL were 3.41 (95% CI, 1.93-6.03) times more likely to die than those with counts of at least 200/microL.

CONCLUSION

Our data demonstrate uniformly low rates of disease progression to death and AIDS or death among patients starting antiretroviral therapy with CD4 cell counts of at least 200/microL. In our study, disease progression to death and AIDS or death was clustered among patients starting therapy with CD4 cell counts less than 200/microL.

CCR5Delta32 and promoter polymorphisms are not correlated with initial virological or immunological treatment response

OBJECTIVE

Natural genetic polymorphisms within the CCR5 gene and promoter have been linked to patterns of HIV-1 clinical disease progression in untreated individuals. The objective of this retrospective study was to assess the influence of the CCR5Delta32 mutation and promoter polymorphisms on virological and immunological treatment outcome in 436 antiretroviral-naive individuals initiating their first therapy, over a mean follow-up time of 22 months.

METHODS

Genotypes for the CCR5Delta32 and promoter were determined by polymerase chain reaction amplification of human DNA from plasma, followed by gel electrophoresis for CCR5Delta32 or DNA sequencing for the promoter polymorphisms. Time to virological failure [defined as the second plasma viral load > or = 400 copies HIV-1 RNA/ml) and immunological failure (defined as time to achieve two successive CD4 cell counts below baseline) were analyzed by Kaplan-Meier methods.

RESULTS

The five most common CCR5 promoter polymorphisms were observed at positions 208(G/T), 303(A/G), 627(C/T), 676(A/G), and 927(C/T). Allele frequencies were 0.24(208T), 0.38(303G), 0.44(627T), 0.35(676G) and 0.18(927T). The CCR5Delta32 allele frequency was 0.08. The promoter polymorphisms existed in strong linkage disequilibrium with each other and the Delta32. No significant effect of the individual CCR5Delta32 or promoter polymorphisms could be demonstrated with respect to time to treatment failure as defined by virological or immunological parameters (P > or = 0.07). Similarly, when combined CCR5Delta32 and promoter genotypes were analyzed in order to account for linkage disequilibrium, no significant effect was observed on time to virological or immunological failure (P > 0.6).

CONCLUSION

CCR5Delta32 and promoter genotypes may not be of clinical relevance in predicting initial virological or immunological response to antiretroviral therapy.

World-wide variation in HIV-1 phenotypic susceptibility in untreated individuals: biologically relevant values for resistance testing

OBJECTIVES

To examine the natural phenotypic variability in drug susceptibility among recombinant HIV-1 isolates from a large number of untreated HIV-positive individuals from wide-ranging geographic locations, and to use this information to establish biologically relevant cut-off values for phenotypic antiretroviral susceptibility testing.

METHODS

Phenotypic susceptibility to 14 antiretroviral agents was determined for HIV-1 samples from > 1000 treatment-naive individuals in seven clinical trials. Samples were from the USA (n = 351), Germany (n = 306), Canada (n = 265), and South Africa (n = 358). Geometric mean fold-resistance and confidence intervals were determined relative to a standard laboratory wild-type virus.

RESULTS

Baseline fold-resistance was approximately log-normally distributed for all antiretroviral agents examined. There was no evidence of large geographical differences in average antiviral susceptibility. Geometric mean fold-resistance for each of 14 antiviral agents was similar (+/- 0.5-fold) for samples derived from the USA, Canada, Germany, or South Africa. The non-nucleoside reverse transcriptase inhibitors (NNRTI) exhibited the broadest distribution of susceptibility; approximately 97.5% of all isolates had < 2.5-4.0, < 3.0-4.5, and < 5-10 fold-decrease in susceptibility to five protease inhibitors, six nucleoside analogues, and three NNRTI, respectively. No consistent geographic pattern or clade effect (B versus C) in either the mean or the distribution of baseline antiretroviral susceptibility was observed.

CONCLUSIONS

Phenotypic drug susceptibility of HIV-1 in untreated individuals varies markedly from drug to drug, with broadly similar patterns world-wide. These results have important implications in defining the 'normal range' of phenotypic susceptibility to antiretroviral agents and establish biologically relevant cut-off values for this phenotypic drug susceptibility test.

Unsafe injection practices in a cohort of injection drug users in Vancouver: could safer injecting rooms help?

BACKGROUND

In several European countries safer injecting rooms have reduced the public disorder and health-related problems of injection drug use. We explored factors associated with needle-sharing practices that could potentially be alleviated by the availability of safer injecting rooms in Canada.

METHODS

The Vancouver Injection Drug User Study is a prospective cohort study of injection drug users (IDUs) that began in 1996. The analyses reported here were restricted to the 776 participants who reported actively injecting drugs in the 6 months before the most recent follow-up visit, during the period January 1999 to October 2000. Needle sharing was defined as either borrowing or lending a used needle in the 6-month period before the interview.

RESULTS

Overall, 214 (27.6%) of the participants reported sharing needles during the 6 months before follow-up; 106 (13.7%) injected drugs in public, and 581 (74.9%) reported injecting alone at least once. Variables independently associated with needle sharing in a multivariate analysis included difficulty getting sterile needles (adjusted odds ratio [OR] 2.7, 95% confidence interval [CI] 1.8-4.1), requiring help to inject drugs (adjusted OR 2.0, 95% CI 1.4-2.8), needle reuse (adjusted OR 1.8, 95% CI 1.3-2.6), frequent cocaine injection (adjusted OR 1.6, 95% CI 1.1-2.3) and frequent heroin injection (adjusted OR 1.5, 95% CI 1.04-2.1). Conversely, HIV-positive participants were less likely to share needles (adjusted OR 0.5, 95% CI 0.4-0.8), although 20.2% of the HIV-positive IDUs still reported sharing needles.

INTERPRETATION

Despite the availability of a large needle-exchange program and targeted law enforcement efforts in Vancouver, needle sharing remains an alarmingly common practice in our cohort. We identified a number of risk behaviours--difficulty getting sterile needles, needle sharing and reuse, injection of drugs in public and injecting alone (one of the main contributing causes of overdose)--that may be alleviated by the establishment of supervised safer injecting rooms.