Scoring treatment response in patients with relapsing multiple sclerosis.

BACKGROUND: We employed clinical and magnetic resonance imaging (MRI) measures in combination, to assess patient responses to interferon in multiple sclerosis. OBJECTIVE: To optimize and validate a scoring system able to discriminate responses to interferon treatment in patients with relapsing-remitting multiple sclerosis (RRMS). METHODS: Our analysis included two large, independent datasets of RRMS patients who were treated with interferons that included 4-year follow-up data. The first dataset ("training set") comprised of 373 RRMS patients from a randomized clinical trial of subcutaneous interferon beta-1a. The second ("validation set") included an observational cohort of 222 RRMS patients treated with different interferons. The new scoring system, a modified version of that previously proposed by Rio et al., was first tested on the training set, then validated using the validation set. The association between disability progression and risk group, as defined by the score, was evaluated by Kaplan Meier survival curves and Cox regression, and quantified by hazard ratios (HRs). RESULTS: The score (0-3) was based on the number of new T2 lesions (>5) and clinical relapses (0,1 or 2) during the first year of therapy. The risk of disability progression increased with higher scores. In the validation set, patients with score of 0 showed a 3-year progression probability of 24%, while those with a score of 1 increased to 33% (HR = 1.56; p = 0.13), and those with score greater than or equal to 2 increased to 65% (HR = 4.60; p < 0.001). CONCLUSIONS: We report development of a simple, quantitative and complementary tool for predicting responses in interferon-treated patients that could help clinicians make treatment decisions.

Combined MRI lesions and relapses as a surrogate for disability in multiple sclerosis.

OBJECTIVE: In multiple sclerosis (MS), the aim of therapies is to prevent the accumulation of irreversible disability. This is difficult to assess given the short time course of clinical trials. MRI markers and relapses are often used as surrogate of disability in MS studies, but their validity remains controversial. We sought to validate, at the individual patient level, MRI lesions and relapses as surrogates for disability progression over the course of MS trials. METHODS: Individual patient data from a large, placebo-controlled trial of interferon ß-1a in relapsing-remitting MS (RRMS) were analyzed. The Prentice criteria were applied to evaluate surrogacy of 1-year MRI active lesions and relapses for disability worsening (Expanded Disability Status Scale [EDSS]) over the 2-year follow-up. RESULTS: All Prentice criteria were satisfied. Treatment reduced by 31% the odds of having EDSS worsening over 2 years, reducing the mean number of MRI lesions by 61% and the mean number of relapses by 36% over 1 year. Both 1-year MRI lesion activity and relapses, when considered independently, accounted for more than 60% of the treatment effect on 2-year EDSS worsening. A combination of 1-year MRI lesion activity and relapses explained 100% of the treatment effect on EDSS worsening over 2 years. CONCLUSIONS: A combined measure of 1-year changes in MRI lesions and relapses after interferon therapy fully estimated the corresponding effect on 2-year EDSS worsening. This short-term combined measure appears to be a surrogate for disability progression over a longer term when evaluating the effect of interferon in RRMS.

Incidence of hepatitis C virus infection among injection drug users during an outbreak of HIV infection.

BACKGROUND: Beginning in 1994, Vancouver experienced an explosive outbreak of HIV infection among injection drug users (IDUs). The objectives of this study were to measure the prevalence and incidence of hepatitis C virus (HCV) infection in this context and to examine factors associated with HCV seroconversion among IDUs. METHODS: IDUs recruited through a study site and street outreach completed interviewer-administered questionnaires covering subjects' characteristics, behaviour, health status and service utilization and underwent serologic testing for HIV and HCV at baseline and semiannually thereafter. A Cox proportional hazards model was used to identify independent correlates of HCV seroconversion. RESULTS: As of Nov. 30, 1999, 1345 subjects had been recruited into the study cohort. The prevalence of anti-HCV antibodies was 81.6% (95% confidence interval [CI] 79.6% to 83.6%) at enrollment. Sixty-two HCV seroconversions occurred among 155 IDUs who were initially HCV negative and who returned for follow-up, for an overall incidence density rate of 29.1 per 100 person-years (95% CI 22.3 to 37.3). The HCV incidence remained above 16 per 100 person-years over 3 years of observation (December 1996 to November 1999), whereas HIV incidence declined from more than 19 to less than 5 per 100 person-years. Independent correlates of HCV seroconversion included female sex, cocaine use, injecting at least daily and frequent attendance at a needle exchange program. INTERPRETATION: Because of high transmissibility of HCV among those injecting frequently and using cocaine, the harm reduction initiatives deployed in Vancouver during the study period proved insufficient to eliminate hepatitis C transmission in this population.

Comparison of sexual behaviors, unprotected sex, and substance use between two independent cohorts of gay and bisexual men.

OBJECTIVE: To compare demographic characteristics, sexual practices, unprotected receptive and insertive anal intercourse, substance use and rates of HIV-1 seroconversion between two prospective cohorts of HIV-negative men who have sex with men. DESIGN: Comparative analysis of two independent cohorts. METHODS: Between May 1995 and April 1996, 235 HIV-negative Vanguard Project (VP) participants were enrolled and between January and December 1985, 263 HIV-negative participants in the Vancouver Lymphadenopathy AIDS Study (VLAS) completed a follow-up visit. The VP participants were compared with VLAS participants with respect to self-reported demographic variables, sexual behaviors, unprotected sex, substance use and rates of HIV-1 seroconversion during follow-up. RESULTS: In comparison with the VLAS participants the VP participants were younger (median age, 26 versus 34 years; P< 0.001), more likely to be non-Caucasian (75 versus 97%; P< 0.001), and were less likely to have attended university/college (35 versus 46%; P = 0.014). The VP participants reported a higher mean number of male sex partners in the previous year (15 versus 12; P= 0.026) and a higher mean number of regular partners (1.7 versus 0.6; P < 0.001). The VP participants were more likely to report engaging in receptive (92 versus 60%; P< 0.001) and insertive (90 versus 69%; P < 0.001) anal intercourse with regular partners and receptive anal intercourse with casual partners (62 versus 38%; P< 0.001). The VLAS participants were more likely to report never using condoms during insertive and receptive anal intercourse with both regular and casual partners. The VP participants were less likely to report using nitrite inhalants (34 versus 43%; P= 0.033), but more likely to report the use of cocaine (30 versus 8%; P< 0.001), LSD (21 versus 3%; P < 0.001), amphetamine (11 versus 1%; P< 0.001), heroin (3 versus 0%; P= 0.010) and methyldiamphetamine (17 versus 10%; P= 0.034). The VLAS participants were nine times more likely to report high-risk sexual behavior, after controlling for differences in age, ethnicity, substance use, and method of recruitment between cohort members. After adjustment for differences in demographics, sexual behaviors, and level of substance use, the risk ratio for seroconversion among VLAS participants remained significantly elevated compared with VP participants. CONCLUSION: These data provide evidence that men who have sex with men who were enrolled in the VP were more sexually active than their VLAS counterparts were 10 years ago as measured by self-reported numbers of regular and casual partners and frequency of anal intercourse with these partners. However, condom use appears to be significantly higher among VP participants, which has contributed to a lower rate of HIV-1 infection.

The impact of zidovudine on dementia-free survival in a population of HIV-positive men and women on antiretroviral therapy.

Our objective was to characterize the effect of zidovudine therapy on AIDS dementia complex (dementia) free survival among HIV-infected men and women in a population-based cohort with free access to antiretroviral therapy in the province of British Columbia. Time to diagnosis of dementia among individuals was examined on the basis of zidovudine duration, CD4+ cell count at first treatment, gender, and transmission group [men having sex with men (MSM), intravenous drug users (IDU), heterosexuals]. We restricted the analysis to subjects with CD4+ cells counts within 12 months prior to treatment start date. Among 641 participants eligible for analysis, median duration of follow-up was 3.6 years, under which 86 (9.3%) events of dementia occurred. Participants were less likely to develop dementia with: increased zidovudine exposure (OR=0.26, 95% CI: 0.14-0.49), at least 260 CD4+ cells/mm3 (median) (OR=0.52, 95% CI: 0.34-0.78), and MSM risk group (OR=0.57, 95% CI: 0.35-0.94). Those infected through heterosexual contact had an increased risk (RR=2.04, 95% CI: 1.02-4.07). Using Cox's proportional hazards model, controlling for CD4+ cell count at treatment start date, independent predictors of dementia-free survival were: duration of zidovudine (OR=0.28, 95% CI: 0.15-0.52) and MSM transmission group (OR=0.61, 95% CI: 0.37-1.00). In this observational treatment cohort, factors associated with dementia-free survival include duration of zidovudine (AZT) therapy and MSM transmission group. It is not clear from these data whether the AZT protective effect is exclusive to this agent or whether other therapies might offer a similar protective effect.

HIV infection and risk behaviours among young gay and bisexual men in Vancouver.

BACKGROUND: Young gay and bisexual men may perceive that the consequences of HIV infection have dramatically improved with the availability of highly active antiretroviral therapy. We therefore sought to identify trends in HIV infection rates and associated risk behaviours among young gay and bisexual men in Vancouver. METHODS: Prospective cohort study involving gay and bisexual men aged 18-30 years who had not previously tested HIV positive. Subjects were recruited through physicians, clinics and community outreach in Vancouver. Annually participants were tested for HIV antibodies and asked to complete a self-administered questionnaire pertaining to sociodemographic characteristics, sexual behaviours and substance use. Prevalence of HIV infection and risk behaviours were determined for eligible participants who completed a baseline questionnaire and HIV testing as of May 1998. The primary outcome was the proportion of men who reported having protected sex during the year before enrollment and who reported any episode of unprotected sex by the time of the first follow-up visit. RESULTS: A total of 681 men completed a baseline questionnaire and HIV testing as of May 1998. The median duration between baseline and the first follow-up visit was 14 months. The median age was 25 years. Most of the subjects were white and of high socioeconomic status. The majority (549 [80.6%]) reported having sex only with men; 81 (11.9%) reported bisexual activity. Of the 503 men who had one or more regular male partners, 245 (48.7%) reported at least one episode of unprotected anal sex in the year before enrollment; the corresponding number among the 537 who had one or more casual male partners was 140 (26.1%). The prevalence and incidence of HIV seropositivity were 1.8% (95% confidence interval [CI] 0.8%-2.8%) and 1.7 per 100 person-years [95% CI 0.7-2.7], respectively. Fifty-two (26.5%) of the 196 and 55 (29.7%) of the 185 men with regular partners who reported having practiced protected insertive and receptive anal sex in the year before the baseline visit reported engaging in these activities without a condom at the follow-up visit; the corresponding numbers among the 232 and 242 men with causal partners who had practiced protected insertive and receptive anal sex before the baseline visit were 43 (15.5%) and 26 (9.4%) respectively at follow-up. INTERPRETATION: The incidence of HIV infection is unacceptably high among this cohort of young gay and bisexual men. Preliminary results suggest a disturbing trend toward increasing levels of unprotected anal intercourse.

The social determinants of emergency department and hospital use by injection drug users in Canada.

OBJECTIVE: The aim of this study was to describe the relationship between sociodemographic characteristics and human immunodeficiency (HIV) status of a cohort of injection drug users (IDUs) on their self-reported health service utilization. DESIGN: Interviewer-administered questionnaire. METHODS: IDUs who had injected illicit drugs within the previous month were recruited through street outreach. They underwent serology for HIV-1 and questionnaires on demographics, drug using behaviors, housing status, and health service utilization (hospitalization overnight and emergency department visits) in the previous 6 months. Logistic regression analysis was used to identify independent associations with the use of health services. RESULTS: Of 1,103 cohort participants, 65% were male, 63% were white, and 23% were HIV positive. Cocaine was the most frequently injected drug used. Almost half (47%) had used health services in the previous 6 months. The following variables were associated independently with health service utilization (adjusted odds ratio; 95% confidence interval): unstable housing, defined as living primarily in a hotel, boarding room, or transition house or on the street in the past 6 months (1.44; 1.11-1.86); female gender (1.45; 1.11-1.89); HIV-positive status (1.43; 1.06-1.92); injection of cocaine (1.50; 1.12-2.02); and primary care I physician visit in past 6 months (1.91; 1.39-2.64). CONCLUSION: IDUs with unstable housing were more likely to report emergency department and hospital use, which may be a reflection of their disorganized lifestyle or poorer health status. Further studies are required to assess the effect on the health status and health care use of IDUs of interventions that increase the availability of safe, affordable housing.

HIV-associated risk factors among young Canadian Aboriginal and non-Aboriginal men who have sex with men.

Young Aboriginal men face marginalization distinct in cause but similar in pattern to those seen among men who have sex with men (MSM) and may be at increased risk for HIV infection. We compared sociodemographic characteristics and risk taking behaviours associated with HIV infection among MSM of Aboriginal and non-Aboriginal descent. Data for this comparison were gathered from baseline questionnaires completed by participants in a cohort study of young MSM. Data collection included: demographic characteristics such as age, length of time residing in the Vancouver region, housing, employment, income and income sources; mental health and personal support; instances of forced sex and sex trade participation and; sexual practices with regular and casual male sex partners. Data were available for 57 Aboriginal and 624 non-Aboriginal MSM. Aboriginal MSM were significantly less likely to be employed, more likely to live in unstable housing, to have incomes of <$10,000 and to receive income assistance than non-Aboriginals (all P<0.01). Aboriginals also had higher depression scores (P<0.01), were more likely to report non-consensual sex (P=0.03), sexual abuse during childhood (P=0.04) and having been paid for sex (P<0.01). In the past year they were no more likely to have had sex with a male partner they knew to be HIV positive, to have had more than 50 male partners or to have unprotected anal insertive or receptive intercourse with their male partners (all P>0.05). Our data indicate that among MSM, Aboriginal men are at increased risk of antecedent risk factors for HIV infection including sexual abuse, poverty, poor mental health and involvement in the sex trade.

Do needle exchange programmes increase the spread of HIV among injection drug users?: an investigation of the Vancouver outbreak.

OBJECTIVE: An association between needle exchange attendance and higher HIV prevalence rates among injecting drug users (IDU) in Vancouver has been interpreted by some to suggest that needle exchange programmes (NEP) may exacerbate HIV spread. We investigated this observed association to determine whether needle exchange was causally associated with the spread of HIV. DESIGN AND METHOD: Prospective cohort study of 694 IDU recruited in the downtown eastside of Vancouver. Subjects were HIV-negative at the time of recruitment and had injected illicit drugs within the previous month. RESULTS: Of 694 subjects, the 15-month cumulative HIV incidence was significantly elevated in frequent NEP attendees (11.8+/-1.7 versus 6.2+/-1.5%; log-rank P = 0.012). Frequent attendees (one or more visits per week) were younger and were more likely to report: unstable housing and hotel living, the downtown eastside as their primary injecting site, frequent cocaine injection, sex trade involvement, injecting in 'shooting galleries', and incarceration within the previous 6 months. The Cox regression model predicted 48 seroconversions among frequent attendees; 47 were observed. Although significant proportions of subjects reported obtaining needles, swabs, water and bleach from the NEP, only five (0.7%) reported meeting new friends or people there. When asked where subjects had met their new sharing partners, only one out of 498 respondents cited the needle exchange. Paired analysis of risk variables at baseline and the first follow-up visit did not reveal any increase in risk behaviours among frequent attendees, regardless of whether they had initiated drug injection after establishment of the NEP. CONCLUSIONS: We found no evidence that this NEP is causally associated with HIV transmission. The observed association should not be cited as evidence that NEP may promote the spread of HIV. By attracting higher risk users, NEP may furnish a valuable opportunity to provide additional preventive/support services to these difficult-to-reach individuals.

Experience in treating persons with HIV/AIDS and the legalization of assisted suicide: the views of Canadian physicians.

The objective of this study is to determine the opinions of a random sample of Canadian family physicians and a population of non-specialist physicians known to provide care to persons with HIV/AIDS about the legalization of physician assisted suicide for persons with HIV disease. In addition, we have attempted to ascertain the physician characteristics that may be associated with a favourable or negative opinion. Self-administered, anonymous questionnaires were mailed to 2,890 family physicians across Canada. Logistic regression analysis was used to determine whether physician characteristics were predictive of agreement with the legalization of physician assisted suicide. Of the respondents who had an opinion, 60% agreed with the legalization of physician assisted suicide. Multivariate analyses indicated that physicians who were living in the provinces of British Columbia (BC), Ontario, or Québec (OR = 1.63, 95% CI: 1.10, 2.43) and who provided routine follow-up care (OR = 1.85, 95% CI: 1.30, 2.63) or palliative care (OR 1.66, 95% CI: 1.13, 2.44) to those with HIV disease were more likely to agree with legalization of physician assisted suicide. This analysis demonstrates a strong support for the legalization of physician assisted suicide for persons with HIV disease among physicians experienced in providing care to those affected.

Determinants of sexual risk-taking among young HIV-negative gay and bisexual men.

Data from a cohort of young HIV-negative gay and bisexual men were analyzed to identify determinants of sexual risk-taking at baseline. Gay/bisexual men aged between 18 and 30 completed a self-administered questionnaire including demographics, depression, social support, substance use, and consensual versus nonconsensual sex. Risk-takers were defined as those who had unprotected anal sex with casual male sex partners in the previous year; non-risk-takers were defined as those who reported consistent condom use during anal sex with all male partners in the previous year. Logistic regression was used to identify independent predictors of sexual risk-taking. Of 439 men studied, risk-takers had less education, a higher depression score, less social support, and were more likely to report nonconsensual sex and recreational drug use relative to non-risk-takers. Independent predictors of sexual risk-taking were low education, nitrite use, low social support (adjusted odds ratio [AOR]=1.65; 95% CI, 1.04-2.59), and nonconsensual sex experienced as a youth or adult (AOR=1.85; 95% CI, 1.15-2.96). Young gay/bisexual men reporting nonconsensual sex, low social support, or nitrite use were significantly more likely to have recently had unprotected anal sex with casual partners. HIV prevention programs aimed at young gay/bisexual men should include sexual abuse counselling and foster community norms supporting safer sex practices.

Models of survival in HIV infection and their use in the quantification of treatment benefits.

Because acquired immunodeficiency syndrome (AIDS) is a shifting endpoint and sufficient follow-up data now allow modeling of survival time (i.e., time from human immunodeficiency virus (HIV) seroconversion to death), the authors evaluated non-parametric and parametric models of mortality with the use of data from 554 seropositive participants in the Vancouver Lymphadenopathy-AIDS Study. The authors then applied these models to quantify treatment benefits at the national level in Canada, using back-calculation and forward-projection based on death registries. The study revealed that the lognormal model better describes survival time than the Weibull model. Relative to observations prior to 1987, later observations (in the era of treatment) revealed a statistically significant change in disease progression: the median survival time increased from 10.1 to 12.0 years, but no further survival improvements were observed in the early 1990s. Concurrent with the increase in availability of treatment, the authors have observed pronounced treatment benefits at the national level: prior to 1995, approximately 1,500 deaths were prevented and 4,200 person-years of life were saved. Also, mortality rates were observed to level off in the mid-1990s due to the shape of the historical HIV infection curve and the accumulating availability of treatment in Canada.

Accuracy of oxygen delivery by liquid oxygen canisters.

The oxygen flow rate delivered by liquid oxygen canisters may be less than intended, owing to inaccuracies of the set flow rates and/or as a result of the outflow resistance caused by the humidifier, oxygen tubing, delivery or conserving device. The aim of this study was to investigate the accuracy of oxygen delivery by liquid oxygen canisters at different flow rates and levels of outflow resistance. Four stationary and 18 portable liquid oxygen canisters from three manufacturers were tested. All flows were measured using a Timemeter RT 200 Calibration Analyser. An adjustable obstruction was used to calculate the effect of the outflow resistance on the delivered flow rate. The measured and set flow rates of both stationary and portable canisters were strongly correlated. Expressed as a percentage of the set flow rate, the measured flow rate of the canisters varied from 36-128%, with the lowest values at flow rates <1 L x min(-1). Sixty-two (26%) of the measured flow rates differed > or =10% from the set flow rate. A difference of 0.5-1.0 L x min(-1) occurred in 16 (7%) of the measurements, but only at set flow rates >2 L x min(-1). Irrespective of the set flow rate, the measured flow rate was hardly affected by the outflow resistance. We conclude that the accuracy of oxygen delivery by liquid oxygen canisters depends on the inaccuracy of the set flow rates rather than on the outflow resistance, even at high flow rates. Although the differences between the measured and set flow rates were mostly small, they may have clinical significance, particularly in patients with chronic obstructive pulmonary disease. To prevent inaccuracy, monthly checks of the canisters by the oxygen provider at the patient's home are more important than yearly maintenance.

Barriers to use of free antiretroviral therapy in injection drug users.

CONTEXT: In British Columbia, human immunodeficiency virus (HIV)-infected persons eligible for antiretroviral therapy may receive it free but the extent to which HIV-infected injection drug users access it is unknown. OBJECTIVE: To identify patient and physician characteristics associated with antiretroviral therapy utilization in HIV-infected injection drug users. DESIGN: Prospective cohort study with record linkage between survey data and data from a provincial HIV/AIDS (acquired immunodeficiency syndrome) drug treatment program. SETTING: British Columbia, where antiretroviral therapies are offered free to all persons with HIV infection with CD4 cell counts less than 0.50 x 10(9)/L (500/microL) and/or HIV-1 RNA levels higher than 5000 copies/mL. SUBJECTS: A total of 177 HIV-infected injection drug users eligible for antiretroviral therapy, recruited through the prospective cohort study since May 1996. MAIN OUTCOME MEASURES: Patient use of antiretroviral drugs through the provincial drug treatment program and physician experience treating HIV infection. RESULTS: After a median of 11 months after first eligibility, only 71 (40%) of 177 patients had received any antiretroviral drugs, primarily double combinations (47/71 [66%]). Both patient and physician characteristics were associated with use of antiretroviral drugs. After adjusting for CD4 cell count and HIV-1 RNA level at eligibility, odds of not receiving antiretrovirals were increased more than 2-fold for females (odds ratio [OR], 2.53; 95% confidence interval [CI], 1.08-5.93) and 3-fold for those not currently enrolled in drug or alcohol treatment programs (OR, 3.49; 95% CI, 1.45-8.40). Younger drug users were less likely to receive therapy (OR, 0.47/10-y increase; 95% CI, 0.28-0.80). Those with physicians having the least experience treating persons with HIV infection were more than 5 times less likely to receive therapy (OR, 5.55; 95% CI, 2.49-12.37). CONCLUSIONS: Despite free antiretroviral therapy, many HIV-infected injection drug users are not receiving it. Public health efforts should target younger and female drug users, and physicians with less experience treating HIV infection.

Is AIDS a floating point between HIV seroconversion and death? Insights from the Tricontinental Seroconverter Study.

OBJECTIVE: To investigate the significance of the time from seroconversion to AIDS (incubation time) and other covariates for survival from AIDS to death. METHODS: In survival analysis, survival from AIDS to death was compared for different categories of length of incubation time adjusted and unadjusted for other covariates, and significant predictors for survival from AIDS to death were investigated. RESULTS: Survival after AIDS was not affected by the incubation time in univariate as well as in multivariate analyses. Predictive factors for progression from AIDS to death were age at seroconversion, type of AIDS diagnosis, and CD4 cell count at AIDS. The relative hazard for age at seroconversion increased 1.38-fold over 10 years. Men with a CD4 cell count at AIDS of <130 x 10(6)/l had a twofold higher risk in progression to death than men with higher CD4 cell counts. Persons diagnosed with lymphoma had a sixfold higher risk of progression to death than persons with Kaposi's sarcoma or opportunistic infections. CONCLUSIONS: The incubation time as well as other factors before AIDS did not affect survival after AIDS. Survival from AIDS to death can be predicted by data obtained at the time of AIDS diagnosis, such as type of diagnosis, age and CD4 cell count. AIDS seems to be a significant point in progression to death, and not just a floating point between infection and death affected by prior factors for persons who did not receive effective therapy and did not have long incubation times.

Needle exchange is not enough: lessons from the Vancouver injecting drug use study.

OBJECTIVE: To describe prevalence and incidence of HIV-1, hepatitis C virus (HCV) and risk behaviours in a prospective cohort of injecting drugs users (IDU). SETTING: Vancouver, which introduced a needle exchange programme (NEP) in 1988, and currently exchanges over 2 million needles per year. DESIGN: IDU who had injected illicit drugs within the previous month were recruited through street outreach. At baseline and semi-annually, subjects underwent serology for HIV-1 and HCV, and questionnaires on demographics, behaviours and NEP attendance were completed. Logistic regression analysis was used to identify determinants of HIV prevalence. RESULTS: Of 1006 IDU, 65% were men, and either white (65%) or Native (27%). Prevalence rates of HIV-1 and HCV were 23 and 88%, respectively. The majority (92%) had attended Vancouver's NEP, which was the most important syringe source for 78%. Identical proportions of known HIV-positive and HIV-negative IDU reported lending used syringes (40%). Of HIV-negative IDU, 39% borrowed used needles within the previous 6 months. Relative to HIV-negative IDU, HIV-positive IDU were more likely to frequently inject cocaine (72 versus 62%; P < 0.001). Independent predictors of HIV-positive serostatus were low education, unstable housing, commercial sex, borrowing needles, being an established IDU, injecting with others, and frequent NEP attendance. Based on 24 seroconversions among 257 follow-up visits, estimated HIV incidence was 18.6 per 100 person-years (95% confidence interval, 11.1-26.0). CONCLUSIONS: Despite having the largest NEP in North America, Vancouver has been experiencing an ongoing HIV epidemic. Whereas NEP are crucial for sterile syringe provision, they should be considered one component of a comprehensive programme including counselling, support and education.

Determinants of HIV seroconversion in injection drug users during a period of rising prevalence in Vancouver.

To identify determinants of HIV seroconversion among injection drug users (IDUs) during a period of rising prevalence, a case-control investigation was conducted. Cases were IDUs with a new positive test after 1 January 1994, and a negative test within the prior 18 months. Controls required 2 negative tests during the same period. Subjects completed a questionnaire on demographic, psychosocial, and behavioural factors. Eighty-nine cases and 192 controls were similar with respect to gender, age, ethnicity and inter-test interval. Multivariate analyses of events during the inter-test interval showed borrowing syringes (adj. OR = 2.96; P < 0.006), unstable housing (adj. OR = 2.01; P = 0.03) and injecting > or = 4 times daily (adj. OR = 1.71; P = 0.06) to be independently associated with seroconversion. Protective associations were demonstrated for sex with opposite gender (adj. OR = 0.36; P = 0.001) and tetrahydrocannabinol use (adj. OR = 0.41; P = 0.001). There is a need to evaluate programmes dealing with addiction, housing and the social underpinnings of risk behaviours in this population.

Determinants of complementary therapy use in HIV-infected individuals receiving antiretroviral or anti-opportunistic agents.

OBJECTIVE: To identify sociodemographic and clinical characteristics of persons using complementary therapy in an HIV/AIDS drug treatment program and to evaluate the associations between complementary therapy use and participant characteristics. METHODS: A cross-sectional study using program participants who completed an annual participant survey between 09/95 and 06/96. Surveys gathered data on use and motivations for use of complementary therapies. Complementary therapies included dietary, medicinal, tactile, and relaxation therapies. Statistical analyses were carried out using parametric and nonparametric measures and multivariate logistic analyses. Multivariate modeling considered age, income, education, time spent out of bed, and degree of pain as independent variables against complementary therapy use (Yes versus No). All reported p values are two-sided. RESULTS: A total of 657 participants completed an annual participant survey within the study period. Of these, 256 participants (39%) had ever used complementary therapies. Univariate analysis indicated that 195 patients (30%) had used dietary supplements, 141 (22%) had used herbal and other medicinal therapies, 145 (22%) had used tactile therapies, and 128 (20%) had used mental relaxation techniques. Multivariate analysis indicated that complementary use was independently associated with younger median age (p = .003), income >$7,300 U.S. (p = .014), having greater physical pain (p = .003), and a university education (p = .002). CONCLUSION: Use of complementary therapies in conjunction with HIV/AIDS medications appears to be most prevalent in young and highly educated individuals and to be associated with the debilitating and chronic nature of HIV disease.

Determinants of HIV-related high risk behaviours among young offenders: a window of opportunity.

PURPOSE: To study HIV-associated risk behaviours among young offenders. METHODS: Juveniles aged 12 to 19 years entering correctional facilities in British Columbia volunteered in an unlinked anonymous study. Logistic regression was used to identify factors associated with high-risk sexual behaviours and injection drug use (IDU). RESULTS: Despite low HIV prevalence (0.25%), patterns of risk behaviour were evident. IDU and homosexual/bisexual activity were equally prevalent among youth aged 12 to 15 and 16 to 19 years. For both age groups, IDU and female gender were significant predictors of sex for trade and sex with another drug user. Natives aged 12 to 15 years were five times more likely to inject drugs than non-Natives. However, predictors of IDU differed for older vs. younger youth. CONCLUSIONS: Patterns of high-risk activity begin early and selective pressures may differ for younger vs. older young offenders. Youth in detention provide a window of opportunity for enhanced HIV/AIDS education.

Social determinants predict needle-sharing behaviour among injection drug users in Vancouver, Canada.

Despite the fact that needle exchange was introduced in Vancouver as early as 1988, needle sharing remains common. An analysis was conducted to identify determinants of borrowing used needles among subjects participating in a case-control study. IDUs had a documented HIV seroconversion after 1 January, 1994 (n = 89), or repeatedly tested HIV-seronegative after this date (n = 192). Interviewer-administered questionnaires focused on drug use, sexual behaviours, source of needles and depression. Subjects were asked if they had "ever been forced to have sex" as a child, youth or adult. Logistic regression identified determinants of borrowing needles. After controlling for HIV serostatus, factors independently associated with borrowing were injecting > 4 times/day, polydrug use, and ever experiencing non-consensual sex (AOR = 3.4, 95% CI: 1.8, 6.5). Depression was associated with borrowing, although not independently so. Homosexual activity was independently associated with borrowing among males, whereas living with a sexual partner was an independent predictor for females. Access or barriers to clean needle use were not associated with borrowing. Social determinants, particularly a history of sexual abuse, are among the most significant predictors of needle borrowing among Vancouver's IDUs. Early identification of these factors should be a component of HIV prevention programmes.