Abstract
Objectives
Nonoccupational post-exposure prophylaxis (nPEP) is a strategy to reduce the risk of HIV infection in those with high-risk exposure. This study characterized nPEP awareness among gay, bisexual and other men who have sex with men (MSM) in Metro Vancouver, British Columbia, Canada after a pilot nPEP programme established in 2012.
Methods
Momentum Health Study participants were MSM aged >16 years recruited via respondent-driven sampling (RDS) who completed a computer-assisted self-interview. Stratifying patients by HIV status, we used multivariable logistic regression with backward selection to identify factors associated with nPEP awareness. All analyses were RDS-adjusted.
Results
A total of 51.9% (112 of 173) of HIV-positive and 48.5% (272 of 500) of HIV-negative participants had heard of nPEP. Only 3% (five of 106) of HIV-negative participants who reported recent high-risk sex used nPEP. Generally, nPEP awareness was higher for participants who engaged in sexual activities with increased HIV transmission potential. Other factors associated with greater awareness among HIV-negative participants included recent alcohol use, higher communal sexual altruism, previous sexually transmitted infection (STI) diagnosis, and greater perceived condom use self-efficacy. Factors associated with greater awareness among HIV-negative participants included white race/ethnicity, gay sexual identity, more formal education, higher personal sexual altruism, and Vancouver residence. Greater nPEP awareness among HIV-positive participants was associated with greater perceived agency to ask sexual partners’ HIV status and more frequently reporting doing so, a higher number of lifetime receptive sex partners, and greater access to condoms.
Conclusions
Following implementation of an nPEP pilot programme, nPEP awareness among HIV-negative MSM was 51% and use was 3%. These data support the need to expand access to and actively promote nPEP services.
Keywords: HIV/AIDS prevention, nonoccupational post-exposure prophylaxis, gay and bisexual men, men who have sex with men, clinical health services and promotion
Introduction
Despite widespread promotion of HIV prevention measures, including the expanded access to antiretroviral treatment in Canada, the number of new HIV infections in Canada remains relatively stable at over 3000 new infections per year [1,2]. Gay, bisexual and other men who have sex with men (MSM) remain disproportionally represented compared with other exposure categories, and this population comprised half of all estimated new HIV infections in 2013 [1,3]. The total direct and indirect lifetime economic cost attributed to treatment, loss of productivity and loss of quality of life related to HIV/AIDS over the lifetime of new cases infected in 2009 was an estimated $4 billion Canadian dollars [4]. These current trends point to the need for a combination approach to HIV prevention that draws on the complementary strengths of behavioural, structural and biomedical interventions [5].
Post-exposure prophylaxis (PEP) to reduce the risk of acquiring HIV infection after a single high-risk exposure consists of initiating antiretroviral medications (ARVs) within 72 h and continuing the treatment for 28 consecutive days [6]. Since 1998, PEP has been recommended and used in the USA after occupational exposures, such as a needle-stick injury, for health care providers [6]. This recommendation was based on evidence from a case–control study where an 81% decrease in the risk of acquiring HIV was observed in health care providers after prompt initiation of treatment compared with those who did not initiate treatment [7]. After 2005, PEP was also recommended and used in major US cities in other populations, including MSM, after nonoccupational exposures, such as unprotected sexual activity, nonconsensual sex and condom failures [8]. However, awareness and use of nonoccupational PEP (nPEP) remain relatively low in MSM populations. Previous studies in the USA, Europe and Australia conducted between 2000 and 2012 found that only 28-48% of MSM had heard of nPEP [10-17] and only 1-7% of MSM reported having previously used nPEP [11,12,15,17]. Three of these studies specifically sampled HIV-negative men [10,12,13], whereas the rest of the studies did not sample on the basis of serotype [11,14-17]. The majority of the studies used convenience sampling, with the exception of two studies which used a mixture of convenience sampling and representative sampling [13] and a modified version of respondent-driven sampling [12]. Two Canadian studies on nPEP both focused on clinical factors related to patients who accessed nPEP treatment, rather than nPEP awareness in the overall population [18,19]. Although the true efficacy of PEP in preventing HIV transmission is unknown, it is not thought to be 100% effective and timely access and strict adherence to the treatment regimen are believed to be crucial to maximize this efficacy [8, 9]. Therefore, it should not be used in isolation as a population-based prevention strategy, but rather as one approach within a broader strategy for reducing HIV transmission [20].
We designed a study to describe the sociodemographic, behavioural and psychosocial factors associated with nPEP awareness among MSM in Metro Vancouver, Canada following the implementation of a publicly funded nPEP pilot programme across the region in 2012.
Methods
The nPEP programme began in July 2012 as a pilot between the BC Centre for Excellence in HIV/AIDS and several community health clinics across Metro Vancouver. BC has adopted treatment as prevention (TasP) as a critical public health strategy to reduce HIV morbidity, mortality and onward transmission by suppressing population-level viral load [21]. TasP operates via the Seek and Treat for Optimal Prevention (STOP) programme funded by the BC Ministry of Health, which has provided dedicated funding to increase HIV testing, care and treatment for individuals with HIV/AIDS across all of BC [22].
We analysed data for participants enrolled in the Momentum Health Study, a longitudinal bio-behavioural prospective cohort study of HIV-positive and HIV-negative MSM (≥16 years) in Metro Vancouver, Canada. We used RDS, a novel peer-recruited sampling method that leverages network connections to recruit a diverse and potentially more representative sample of MSM [23]. Seeds were selected from the community through local agencies and online through popular socio-sexual mobile apps. After providing informed consent and completing their study visit, seeds were given up to six coupons to recruit peers into the study. New eligible recruits who completed the baseline visit were then given up to six coupons to recruit their peers; this peer chain recruitment continued wave after wave. Participants were provided with $50 for completing each study visit, and $10 for every eligible peer recruited who completed a baseline study visit. Participants were followed every 6 months with a computer-assisted, self-administrated (CASI) questionnaire and serological testing for HIV, hepatitis C virus and syphilis. The Momentum Health Study received ethical approval from its investigators’ institutional Research Ethics Boards.
Data for this analysis were collected from participants’ first response to the nPEP questions, irrespective of the study visit at which this occurred. As such, questions regarding nPEP were first added in November 2012. All responses received were included up until the end of February 2014, when the last study participant was enrolled. Participants were prompted with a definition of nPEP (“‘PEP’ stands for Post-Exposure Prophylaxis. It’s a treatment that may stop you from contracting HIV after risky sex”) and asked, “Have you ever heard of PEP?” The primary outcome in this study was nPEP awareness (yes versus no). Among those aware of nPEP, a series of subsequent questions were asked that provide additional description and detail regarding MSM’s awareness of nPEP.
Independent variables included sociodemographics, sexual and substance use behaviours, prevention strategies employed, awareness of other HIV prevention strategies in BC, sexual health, and attitudes and beliefs regarding HIV treatment, prevention and condoms. Previously validated scales such as the HAART Treatment Optimism Scale [24], the Sexual Altruism (Personal and Communal) Scale [25], and the Sexual Sensation Seeking Scale – Revised [26] were used. The Sexual Altruism Personal subscale assesses a participant’s values, motivations, and practices of caretaking in their own sexual behaviour to protect their sexual partner(s) from HIV infection, and the Communal subscale assesses the participant’s role in protecting the collective wellbeing of the gay community in relation to HIV prevention [25]. All analyses were conducted using sas version 9.3 (SAS Institute, Cary, NC) and adjusted by weights generated using rdsat version 7.1.46 given use of RDS. We performed descriptive statistics including both crude frequencies and RDS-adjusted population parameters. Bivariate and multivariable logistic regression was used to identify covariates of nPEP awareness, stratified by self-identified HIV status: (1) HIV-positive and (2) HIV-negative or unknown status. Model selections were conducted using a backward elimination technique based on two criteria [Akaike information criterion (AIC) and Type III P-values] until each final model reached the optimum (minimum) AIC [27]. All statistical tests were two-sided and considered significant at α<0.05.
Results
A total of 719 participants were recruited in this study. After RDS adjustment, 68.3% identified as white, 80.3% of all participants identified as gay, 76.7% were HIV-negative at baseline and 23.1% were HIV-positive, the median age was 33 years (1st–3rd quartile 26-47 years), and 51.8% of respondents lived in downtown City of Vancouver. Overall, 65.7% of the sample had education levels higher than high school, 19.1% were currently a student, and 74.1% had an annual income of < $30 000 CDN ($23 000 USD). Other descriptive information on substance use and sexual behaviour, partner characteristics, sexual health and attitudes and beliefs is shown in Table 1.
Table 1.
Sample demographics and descriptive statistics for factors associated with nPEP awareness at univariable Level (p<0.05) for both HIV-negative/unknown MSM (n=524) and HIV-positive MSM (n=195)
| All participants | HIV-negative or unknown | HIV-positive | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | RDS % | RDS 95% CI | n | RDS % | RDS 95% CI | n | RDS % | RDS 95% CI | ||||
| DEMOGRAPHICS | ||||||||||||
| Age (median) | (33) | (29) | (47) | |||||||||
| < 30 | 275 | 33.5 | 25.0 | 42.3 | 267 | 49.0 | 43.0 | 55.1 | 8 | 3.7 | 0.6 | 6.8 |
| ≥ 30 | 444 | 66.5 | 57.7 | 75.0 | 257 | 51.0 | 44.9 | 57.0 | 187 | 96.3 | 93.2 | 99.4 |
| White Ethnicity | ||||||||||||
| Yes | 539 | 68.3 | 61.4 | 74.5 | 390 | 69.8 | 63.9 | 75.7 | 149 | 68.1 | 57.4 | 78.8 |
| No | 180 | 31.7 | 25.5 | 38.6 | 134 | 30.2 | 24.3 | 36.1 | 46 | 31.9 | 21.2 | 42.6 |
| Sexual Identity | ||||||||||||
| Gay | 612 | 80.3 | 75.8 | 85.0 | 445 | 82.2 | 77.3 | 87.0 | 167 | 82.7 | 74.2 | 91.2 |
| Bisexual/Other | 107 | 19.7 | 15.0 | 24.2 | 79 | 17.8 | 13.0 | 22.7 | 28 | 17.3 | 8.8 | 25.8 |
| Education | ||||||||||||
| Greater than high school | 537 | 65.7 | 58.3 | 72.2 | 407 | 71.0 | 64.9 | 77.0 | 130 | 66.0 | 55.6 | 76.5 |
| Some/completed high school | 168 | 34.3 | 27.8 | 41.7 | 107 | 29.0 | 23.0 | 35.1 | 61 | 34.0 | 23.5 | 44.4 |
| Heard of TasP | ||||||||||||
| No | 351 | 53.8 | 47.6 | 59.4 | 299 | 59.1 | 53.2 | 65.0 | 52 | 30.3 | 20.0 | 40.5 |
| Yes | 366 | 46.2 | 40.6 | 52.4 | 224 | 40.9 | 35.0 | 46.8 | 142 | 69.7 | 59.5 | 80.0 |
| SEXUAL BEHAVIOR | ||||||||||||
| Male Anal Number in P6M | ||||||||||||
| 1 | 107 | 19.5 | 14.7 | 25.5 | 80 | 18.3 | 13.1 | 23.4 | 27 | 20.2 | 11.2 | 29.2 |
| 2-5 | 290 | 35.6 | 30.3 | 41.7 | 225 | 40.8 | 35.1 | 46.6 | 65 | 27.9 | 19.1 | 36.6 |
| 6-19 | 146 | 18.3 | 13.3 | 22.8 | 113 | 19.8 | 14.8 | 24.8 | 33 | 16.8 | 9.3 | 24.3 |
| 20+ | 86 | 12.5 | 7.9 | 17.0 | 41 | 8.4 | 4.5 | 12.2 | 45 | 19.8 | 10.1 | 29.4 |
| 0 | 89 | 14.0 | 10.1 | 18.8 | 65 | 12.7 | 8.8 | 16.6 | 24 | 15.4 | 7.2 | 23.5 |
| Life Time Receptive Anal Sex | ||||||||||||
| < 10 | 294 | 47.8 | 41.7 | 54.2 | 260 | 54.7 | 48.7 | 60.7 | 34 | 27.4 | 16.7 | 38.2 |
| ≥ 10 | 425 | 52.2 | 45.8 | 58.3 | 264 | 45.3 | 39.3 | 51.3 | 161 | 72.6 | 61.8 | 83.3 |
| PREVENTION STRATEGIES | ||||||||||||
| Strategic Positioning | ||||||||||||
| No | 506 | 76.3 | 71.7 | 81.0 | 382 | 77.2 | 72.6 | 81.8 | 124 | 67.9 | 58.2 | 77.5 |
| Yes | 209 | 23.7 | 19.0 | 28.3 | 138 | 22.8 | 18.2 | 27.4 | 71 | 32.1 | 22.5 | 41.8 |
| Serosorting for condomless anal sex |
||||||||||||
| No | 431 | 67.1 | 61.1 | 72.9 | 338 | 69.4 | 64.1 | 74.6 | 93 | 53.2 | 42.5 | 63.8 |
| Yes | 284 | 32.9 | 27.1 | 38.9 | 182 | 30.6 | 25.4 | 35.9 | 102 | 46.8 | 36.2 | 57.5 |
| No condoms only if HIV- positive partner has a low viral load or is on treatment |
||||||||||||
| No | 596 | 87.2 | 82.4 | 90.9 | 469 | 91.8 | 88.7 | 94.9 | 127 | 69.2 | 59.6 | 78.7 |
| Yes | 119 | 12.8 | 9.1 | 17.6 | 51 | 8.2 | 5.1 | 11.3 | 68 | 30.8 | 21.3 | 40.4 |
| SEXUAL HEALTH | ||||||||||||
| Previously diagnosed with STI | ||||||||||||
| No | 291 | 47.1 | 40.9 | 53.9 | 275 | 55.8 | 49.8 | 61.9 | 30 | 21.6 | 12.0 | 31.2 |
| Yes | 428 | 52.9 | 46.1 | 59.1 | 249 | 44.2 | 38.1 | 50.2 | 165 | 78.4 | 68.8 | 88.0 |
| ATTITUDES & BELIEF | ||||||||||||
| Sexual Personal Altruism Scale Average, n=606 (median) |
(3.4) | (3.6) | (3.4) | |||||||||
| < 3.4 | 253 | 40.9 | 32.8 | 48.3 | 170 | 40.8 | 34.1 | 47.4 | 83 | 40.7 | 29.6 | 51.9 |
| ≥ 3.4 | 353 | 59.1 | 51.7 | 67.2 | 264 | 59.2 | 52.6 | 65.9 | 89 | 59.3 | 48.1 | 70.4 |
RDS = Respondent-Driven Sampling; 95% CI = 95% Confidence Interval; P6M = Past 6 Months; STI = sexually transmitted infection
Of 673 participants who answered questions regarding nPEP awareness, 45.4% had heard of nPEP. Among HIV-positive participants, 51.9% had heard of nPEP and almost a quarter (23.9%) had talked about it with friends or sexual partners in the past 6 months. For HIV-negative participants, 48.5% had heard of nPEP and a third (30.5%) had talked about it with friends or sexual partners in the past 6 months. Only eight HIV-negative participants [2.9%; 95% confidence interval (CI) 0.00-8.30%] had previously used nPEP; seven of these eight participants obtained the treatment from the nPEP pilot programme. Among HIV-negative participants who reported high-risk sex in the past 6 months (n=106), only five (3.3%; 95% CI 0.00-6.83%) had previously used nPEP; all but one obtained the treatment from the nPEP pilot programme (n=4 of 5). A third of HIV-positive participants (30.4%) and HIV-negative participants (33.2%) reported that they knew “not much, or nothing at all” about nPEP. There was not a statistically significant increase in nPEP awareness over the course of the study period among HIV-negative or unknown participants (p=0.25) but there was a significant increase over the same study period for HIV-positive participants (p<0.005). Tables 2a and b show the RDS-adjusted prevalence of nPEP awareness and univariable associations for all independent variables of interest for MSM (n=673), stratified by HIV status. The adjusted multivariable logistic regression models are shown in Table 3.
Table 2a.
Descriptive statistics and univariable associations of nPEP Awareness for HIV-negative/unknown MSM (n=500)
| Aware of nPEP (n=272) |
Univariable Associations Adjusted for Visit and Time |
||||||
|---|---|---|---|---|---|---|---|
| n | RDS% | RDS 95% CI | AOR | 95% CI | |||
| DEMOGRAPHICS | |||||||
| Age, years (median) | (29) | 0.99 | 0.98 | 1.01 | |||
| Non-White Ethnicity (reference group: White) | 49 | 29.5 | 18.7 | 40.3 | 0.37 | 0.25 | 0.56 |
| Bisexual/Other Sexual Identity (reference group: gay) | 31 | 21.3 | 11.8 | 30.7 | 0.30 | 0.18 | 0.51 |
|
Education: Some/completed high school (reference group: Greater
than high school) |
33 | 32.0 | 18.8 | 45.2 | 0.55 | 0.36 | 0.82 |
|
Heard of Seek and Treat for Optimal Prevention (STOP)
(reference group: No) |
71 | 68.2 | 55.4 | 81.1 | 3.03 | 1.85 | 4.97 |
| Heard of Treatment as Prevention (TasP) (reference group: No) | 149 | 62.2 | 52.2 | 72.2 | 3.08 | 2.11 | 4.48 |
| Neighbourhood (reference group: Downtown City of Vancouver) | |||||||
| Elsewhere in City of Vancouver | 105 | 45.8 | 35.8 | 55.8 | 1.01 | 0.67 | 1.52 |
| Lives Outside City of Vancouver | 46 | 35.4 | 23.7 | 47.1 | 0.56 | 0.35 | 0.89 |
| Student Currently (reference group: Not student currently) | 78 | 51.8 | 39.5 | 64.0 | 1.48 | 0.99 | 2.21 |
|
Annual Income ≥ $30,000 Canadian Dollars (reference group: <
$30,000) |
126 | 53.7 | 44.0 | 63.5 | 1.83 | 1.24 | 2.69 |
| SUBSTANCE USE & SEXUAL BEHAVIOR | |||||||
| Given Drugs in Exchange for Sex in P6M (reference group: No) | 6 | 14.1 | 0.0 | 30.5 | 0.22 | 0.09 | 0.55 |
| Received Drugs in Exchange for Sex in P6M (reference group: No) | 33 | 47.2 | 26.1 | 68.3 | 1.26 | 0.73 | 2.17 |
| Substances Used, P6M (mutually exclusive variables): | |||||||
| Alcohol (reference group: No) | 247 | 45.3 | 38.7 | 51.8 | 1.73 | 1.00 | 2.99 |
| Crystal Methamphetamine (reference group: No) | 28 | 40.2 | 19.9 | 60.4 | 0.96 | 0.56 | 1.64 |
| Cocaine (reference group: No) | 67 | 38.2 | 25.8 | 50.6 | 0.76 | 0.51 | 1.13 |
| Ecstasy (reference group: No) | 79 | 46.9 | 34.2 | 59.7 | 1.14 | 0.75 | 1.74 |
| Ketamine (reference group: No) | 35 | 49.2 | 28.7 | 69.8 | 1.38 | 0.79 | 2.40 |
| GHB (reference group: No) | 41 | 40.9 | 23.3 | 58.6 | 0.90 | 0.54 | 1.49 |
| Male Anal Number in P6M (reference group: 1) | |||||||
| 2-5 | 109 | 43.2 | 34.7 | 51.8 | 1.55 | 0.93 | 2.58 |
| 6-19 | 70 | 52.6 | 37.4 | 67.8 | 2.03 | 1.13 | 3.64 |
| 20+ | 28 | 66.2 | 41.8 | 90.6 | 3.60 | 1.68 | 7.71 |
| 0 | 23 | 33.1 | 16.4 | 49.7 | 0.98 | 0.50 | 1.93 |
| ≥ 10 Life Time Insertive Anal Sex Partners (reference group: < 10) | 152 | 47.2 | 38.4 | 56.0 | 1.24 | 0.87 | 1.76 |
|
≥ 10 Life Time Receptive Anal Sex Partners (reference group: <
10) |
158 | 49.6 | 40.4 | 58.8 | 1.45 | 1.02 | 2.07 |
| High Risk Sex (reference group: No) | 106 | 56.9 | 46.3 | 67.5 | 1.93 | 1.30 | 2.85 |
|
Sex Party Attendance, P6M (reference group: No barebacking-
specific party) |
72 | 60.2 | 45.4 | 75.0 | 1.97 | 1.25 | 3.10 |
| Prevention Strategies (mutually exclusive variables): | |||||||
| Always using condoms (reference group: No) | 166 | 41.6 | 33.8 | 49.3 | 0.80 | 0.55 | 1.16 |
| Strategic positioning (reference group: No) | 81 | 55.6 | 44.3 | 66.9 | 1.77 | 1.16 | 2.71 |
| Anal sex abstinence (reference group: No) | 148 | 52.0 | 43.4 | 60.6 | 1.62 | 1.13 | 2.32 |
| Sero-sorting for condomless anal sex (reference group: No) | 114 | 54.9 | 44.8 | 65.0 | 1.85 | 1.25 | 2.74 |
|
No condoms only if HIV-positive partner has a low viral load or
is on treatment (reference group: No) |
33 | 75.0 | 58.6 | 91.5 | 4.23 | 1.94 | 9.24 |
| Withdrawal (reference group: No) | 87 | 52.6 | 40.5 | 64.7 | 1.56 | 1.03 | 2.36 |
| Ask Partners Their HIV Status (reference group: No) | 180 | 45.2 | 37.4 | 53.0 | 1.15 | 0.80 | 1.67 |
| SEXUAL HEALTH | |||||||
| HIV Tested in Past 2 Years (reference group: No) | 240 | 48.4 | 41.3 | 55.5 | 2.51 | 1.55 | 4.04 |
| No HIV Test Ever (reference group: Yes) | 10 | 22.9 | 6.7 | 39.0 | 0.37 | 0.18 | 0.77 |
| Previously diagnosed with STI (reference group: No) | 149 | 54.7 | 44.9 | 64.5 | 2.06 | 1.43 | 2.95 |
| ATTITUDES & BELIEFS | |||||||
| HAART Treatment Optimism Scale Average (mean) | (27) | 1.05 | 1.00 | 1.10 | |||
| Sexual Altruism Personal Scale Average (mean) | (3.4) | 0.56 | 0.40 | 0.78 | |||
| Sexual Altruism Communal Scale Average (mean) | (3.5) | 0.76 | 0.57 | 1.03 | |||
| Sexual Sensations Seeking Score Average (mean) | (31) | 1.07 | 1.03 | 1.12 | |||
| “Guys Can Always Ask Sexual Partner to Use condoms” (reference group: Strongly Agree) |
|||||||
| Agree | 64 | 52.4 | 38.7 | 66.1 | 1.46 | 0.97 | 2.21 |
| (Strongly) Disagree | 16 | 34.7 | 12.3 | 57.1 | 0.75 | 0.37 | 1.51 |
| “Guys Can Always Ask Sexual Partner HIV Status” (reference group: Strongly Agree) |
|||||||
| Agree | 69 | 43.6 | 31.2 | 55.9 | 0.90 | 0.61 | 1.34 |
| (Strongly) Disagree | 20 | 46.9 | 20.0 | 73.9 | 1.07 | 0.55 | 2.10 |
| “I Can Always Get Condoms” (reference group: Strongly Agree) | |||||||
| Agree | 47 | 38.7 | 26.0 | 51.3 | 0.67 | 0.44 | 1.03 |
| (Strongly) Disagree | 10 | 46.3 | 12.7 | 79.9 | 1.01 | 0.43 | 2.40 |
| “I Always Have Condoms when Having Sex” (reference group: Strongly Agree) |
|||||||
| Agree | 96 | 41.5 | 31.7 | 51.3 | 0.78 | 0.51 | 1.18 |
| (Strongly) Disagree | 70 | 44.2 | 32.0 | 56.4 | 0.83 | 0.54 | 1.29 |
Bolded text indicates statistical significance at p<0.05; AOR = adjusted odds ratio; MSM = gay, bisexual, and other men who have sex with men; RDS= Respondent-Driven Sampling; 95% CI = 95% Confidence Interval; P6M = Past 6 Months; STI = sexually transmitted infection
Table 2b.
Descriptive statistics and univariable associations of nPEP Awareness for HIV-positive MSM (n=173)
| Aware of nPEP (n=112) |
Univariable Associations Adjusted for Visit and Time |
||||||
|---|---|---|---|---|---|---|---|
| n | RDS% | RDS 95% CI | AOR | 95% CI | |||
| DEMOGRAPHICS | |||||||
| Age (median) | (47) | 0.98 | 0.94 | 1.02 | |||
| Non-White Ethnicity (reference group: White) | 22 | 35.1 | 14.9 | 55.3 | 0.34 | 0.16 | 0.73 |
| Bisexual/Other Sexual Identity (reference group: gay) | 12 | 45.5 | 15.5 | 75.5 | 0.69 | 0.27 | 1.73 |
| Education (reference group: Greater than high school) | |||||||
| Some/completed high school | 25 | 36.9 | 16.4 | 57.4 | 0.53 | 0.25 | 1.14 |
| Heard of Seek and Treat for Optimal Prevention (STOP) (reference group: No) |
57 | 51.0 | 32.9 | 69.0 | 0.94 | 0.47 | 1.91 |
|
Heard of Treatment as Prevention (TasP) (reference group:
No) |
91 | 55.9 | 41.7 | 70.1 | 2.51 | 1.13 | 5.59 |
| Neighbourhood (reference group: Downtown City of Vancouver) | |||||||
| Elsewhere in City of Vancouver | 26 | 51.7 | 23.1 | 80.2 | 1.50 | 0.60 | 3.75 |
| Lives Outside City of Vancouver | 15 | 55.3 | 29.3 | 81.3 | 1.62 | 0.57 | 4.61 |
| Student Currently (reference group: Not student currently) | 13 | 60.7 | 28.2 | 93.2 | 1.94 | 0.58 | 6.40 |
| Annual Income ≥ $30,000 Canadian Dollars (reference group: < $30,000) |
35 | 63.7 | 39.2 | 88.3 | 1.95 | 0.78 | 4.87 |
| SUBSTANCE USE & SEXUAL BEHAVIOR | |||||||
| Gave Drugs in Exchange for Sex in P6M (reference group: No) | 18 | 39.0 | 12.3 | 65.7 | 0.53 | 0.24 | 1.20 |
| Received Drugs in Exchange for Sex in P6M (reference group: No) |
37 | 51.8 | 27.2 | 76.4 | 1.18 | 0.54 | 2.54 |
| Substances Used, P6M (mutually exclusive variables): | |||||||
| Alcohol (reference group: No) | 84 | 52.6 | 39.2 | 66.0 | 1.27 | 0.58 | 2.81 |
| Crystal Methamphetamine (reference group: No) | 52 | 61.6 | 42.9 | 80.3 | 2.10 | 0.97 | 4.52 |
| Cocaine (reference group: No) | 30 | 56.0 | 31.8 | 80.1 | 1.16 | 0.53 | 2.54 |
| Ecstasy (reference group: No) | 29 | 64.5 | 32.0 | 97.1 | 2.82 | 0.94 | 8.48 |
| Ketamine (reference group: No) | 26 | 57.9 | 25.8 | 89.9 | 2.34 | 0.83 | 6.64 |
| GHB (reference group: No) | 39 | 66.0 | 43.9 | 88.1 | 2.38 | 1.05 | 5.40 |
| Male Anal Number in P6M (reference group: 1) | |||||||
| 2-5 | 33 | 47.8 | 28.6 | 67.0 | 1.53 | 0.55 | 4.24 |
| 6-19 | 23 | 72.4 | 51.4 | 93.5 | 3.64 | 1.08 | 12.23 |
| 20+ | 35 | 61.7 | 31.1 | 92.3 | 2.77 | 0.89 | 8.65 |
| 0 | 8 | 24.1 | 0.9 | 47.4 | 0.48 | 0.13 | 1.81 |
| ≥ 10 Life Time Insertive Anal Sex Partners (reference group: < 10) |
91 | 50.4 | 37.0 | 63.8 | 1.04 | 0.50 | 2.19 |
|
≥ 10 Life Time Receptive Anal Sex Partners (reference group: < 10) |
101 | 62.2 | 49.6 | 74.8 | 8.96 | 3.41 | 23.50 |
| High Risk Sex (reference group: No) | 57 | 54.8 | 35.9 | 73.8 | 1.37 | 0.65 | 2.88 |
| Sex Party Attendance, P6M (reference group: No barebacking- specific party) |
46 | 57.6 | 36.3 | 78.9 | 1.49 | 0.67 | 3.29 |
| Prevention Strategies (mutually exclusive variables): | |||||||
| Always using condoms (reference group: No) | 36 | 41.0 | 22.0 | 60.0 | 0.56 | 0.27 | 1.19 |
| Strategic positioning (reference group: No) | 46 | 75.2 | 60.7 | 89.7 | 4.51 | 1.97 | 10.31 |
| Anal sex abstinence (reference group: No) | 40 | 42.9 | 23.5 | 62.3 | 0.54 | 0.26 | 1.13 |
| Sero-sorting for condomless anal sex (reference group: No) | 71 | 71.5 | 56.8 | 86.3 | 6.18 | 2.84 | 13.44 |
| No condoms if HIV-positive partner has a low viral load or is on treatment (reference group: No) |
51 | 76.4 | 61.5 | 91.4 | 5.70 | 2.41 | 13.44 |
| Withdrawal (reference group: No) | 33 | 45.3 | 23.4 | 67.2 | 0.73 | 0.32 | 1.67 |
| Ask Partners Their HIV Status (reference group: No) | 63 | 74.6 | 61.9 | 87.3 | 6.25 | 2.67 | 14.64 |
| SEXUAL HEALTH | |||||||
| Previously diagnosed with STI (reference group: No) | 96 | 50.5 | 37.8 | 63.2 | 1.13 | 0.47 | 2.69 |
| ATTITUDES & BELIEFS | |||||||
| HAART Treatment Optimism Scale Average (mean) | (29) | 0.99 | 0.93 | 1.05 | |||
| Sexual Altruism Personal Scale Average (mean) | (3.3) | 0.51 | 0.29 | 0.89 | |||
| Sexual Altruism Communal Scale Average (mean) | (3) | 0.54 | 0.34 | 0.87 | |||
| Sexual Sensations Seeking Score Average (mean) | (32) | 1.00 | 0.93 | 1.08 | |||
|
“Guys Can Always Ask Sexual Partner to Use condoms”
(reference group: Strongly Agree) |
|||||||
| Agree | 43 | 40.3 | 22.1 | 58.4 | 0.41 | 0.18 | 0.92 |
| (Strongly) Disagree | 10 | 36.9 | 5.6 | 68.2 | 0.39 | 0.12 | 1.20 |
|
“Guys Can Always Ask Sexual Partner HIV Status”
(reference group: Strongly Agree) |
|||||||
| Agree | 36 | 34.6 | 18.5 | 50.7 | 0.32 | 0.14 | 0.72 |
| (Strongly) Disagree | 12 | 35.7 | 8.3 | 63.0 | 0.27 | 0.09 | 0.76 |
| “I Can Always Get Condoms” (reference group: Strongly Agree) | |||||||
| Agree | 32 | 42.4 | 23.3 | 61.5 | 0.97 | 0.44 | 2.18 |
| (Strongly) Disagree | 6 | 59.1 | 9.1 | 100.0 | 1.07 | 0.19 | 6.01 |
|
“I Always Have Condoms when Having Sex” (reference
group: Strongly Agree) |
|||||||
| Agree | 28 | 34.0 | 15.8 | 52.2 | 0.73 | 0.31 | 1.74 |
| (Strongly) Disagree | 49 | 78.5 | 64.3 | 92.7 | 4.08 | 1.51 | 11.04 |
Bolded text indicates statistical significance at p<0.05; AOR = adjusted odds ratio;MSM = gay, bisexual, and other men who have sex with men; RDS= Respondent-Driven Sampling; 95% CI = 95% Confidence Interval; P6M = Past 6 Months; STI = sexually transmitted infection
Table 3.
Multivariable factors associated with nPEP awareness stratified by HIV status
| HIV-negative/unknown MSM | HIV-positive MSM | |||||
|---|---|---|---|---|---|---|
| AOR | 95% CI | AOR | 95% CI | |||
| DEMOGRAPHICS | ||||||
| Non-White Ethnicity (reference group: White) | 0.27 | 0.16 | 0.45 | 0.34 | 0.12 | 0.95 |
| Bisexual/Other Sexual Identity (reference group: gay) | 0.43 | 0.23 | 0.81 | |||
|
Some/completed high school education (reference group: greater than high
school) |
0.46 | 0.26 | 0.82 | |||
| Neighbourhood (reference group: Downtown City of Vancouver) | ||||||
| Elsewhere in City of Vancouver | 0.78 | 0.46 | 1.31 | |||
| Outside City of Vancouver | 0.41 | 0.23 | 0.74 | |||
| Student Currently (reference group: No) | 2.23 | 1.32 | 3.75 | |||
| SUBSTANCE USE & SEXUAL BEHAVIOR | ||||||
| Gave Drugs in Exchange for Sex in P6M (reference group: No) | 0.19 | 0.06 | 0.64 | |||
| Used Alcohol in P6M (reference group: No) | 2.36 | 1.10 | 5.06 | |||
| Male Anal Number in P6M (reference group: 1) | ||||||
| 2-5 | 1.24 | 0.65 | 2.39 | |||
| 6-19 | 1.81 | 0.82 | 4.01 | |||
| 20+ | 3.60 | 1.26 | 10.30 | |||
| 0 | 0.85 | 0.37 | 1.98 | |||
| ≥ 10 Life Time Receptive Anal Sex Partners (reference group: < 10) | 5.39 | 1.62 | 17.94 | |||
|
Sex Party Attendance, P6M (reference group: No barebacking-specific
party) |
3.12 | 1.59 | 6.14 | |||
| Prevention Strategies (mutually exclusive variables): | ||||||
| Strategic positioning (reference group: No) | 2.06 | 1.26 | 3.35 | |||
| Sero-sorting for condomless anal sex (reference group: No) | 3.92 | 1.33 | 11.59 | |||
| SEXUAL HEALTH | ||||||
| Previously diagnosed with STI (reference group: No) | 1.86 | 1.14 | 3.04 | |||
| ATTITUDES & BELIEFS | ||||||
| Sexual Altruism Personal Scale | 0.36 | 0.20 | 0.65 | |||
| Sexual Altruism Communal Scale | 1.86 | 1.09 | 3.17 | |||
|
Guys Can Always Ask Sexual Partner to Use condoms (reference group:
Strongly Agree) |
||||||
| Agree | 2.40 | 1.32 | 4.37 | |||
| (Strongly) Disagree | 1.32 | 0.42 | 4.22 | |||
|
Guys Can Always Ask Sexual Partner HIV Status (reference group:
Strongly Agree) |
||||||
| Agree | 0.41 | 0.13 | 1.33 | |||
| (Strongly) Disagree | 0.16 | 0.04 | 0.70 | |||
| I Can Always Get Condoms (reference group: Strongly Agree) | ||||||
| Agree | 0.47 | 0.26 | 0.86 | |||
| (Strongly) Disagree | 0.27 | 0.08 | 0.98 | |||
|
I Always Have Condoms when Having Sex (reference group: Strongly
Agree) |
||||||
| Agree | 1.33 | 0.37 | 4.75 | |||
| (Strongly) Disagree | 5.49 | 1.42 | 21.26 | |||
Bolded text indicates statistical significance at p<0.05; AOR = adjusted odds ratio; RDS= Respondent-Driven Sampling; 95% CI=95% Confidence Interval; P6M =Past 6 Months; STI = sexually transmitted infection
Among HIV-negative participants, nPEP awareness was significantly higher for men who were currently students [adjusted odds ratio (AOR) 2.23; 95% CI 1.32-3.75]; those who, in the past 6 months, used alcohol (AOR 2.36; 95% CI 1.10-5.06), had 20 or more male anal sex partners (AOR 3.60; 95% CI 1.26-10.30) or attended a sex party (AOR 3.12; 95% CI 1.59-6.14); used strategic positioning as an HIV prevention strategy (AOR 2.06; 95% CI 1.26-3.35); had previously been diagnosed with a sexually transmitted infection (STI) (AOR 1.86; 95% CI 1.14-3.04); scored higher on the Communal Sexual Altruism Scale (AOR 1.86; 95% CI 1.09-3.17); and agreed with “Guys always ask sexual partners to use condoms” (AOR 2.40; 95% CI 1.32-4.37). Factors associated with lower odds of nPEP awareness for HIV-negative participants included non-white race/ethnicity (AOR 0.27; 95% CI 0.16-0.45); bisexual/other sexual identity (AOR 0.43; 95% CI 0.23-0.81); less formal education (AOR 0.46; 95% CI 0.26-0.82); residence outside the City of Vancouver but within Metro Vancouver (AOR 0.41; 95% CI 0.23-0.74); scoring higher on the Personal Sexual Altruism Scale (AOR 0.36; 95% CI 0.20-0.65); and giving drugs for sex in the past 6 months (AOR 0.19; 95% CI 0.06-0.64).
Among HIV-positive participants, those who asked their partner’s HIV status “a lot of the time/sometimes” were more likely to be aware of nPEP at the univariable level [odds ratio (OR) 2.91; 95% CI 1.05-8.09]. However, in the multivariable model, nPEP awareness was significantly higher for men who had >10 lifetime receptive anal sex partners (AOR 5.39; 95% CI 1.62-17.94); had condomless sex only with partners of the same status (AOR 3.92; 95% CI 1.33-11.59); and strongly disagreed with the statement “I always have condoms with me when having sex” (AOR 5.49; 95% CI 1.42-21.26). Factors significantly associated with lower odds of nPEP awareness among HIV-positive participants were non-white race/ethnicity (AOR 0.34; 95% CI 0.12-0.95) and strong disagreement with the statement “Guys can always ask sexual partners their HIV status” (AOR 0.16; 95% CI 0.04-0.70).
Discussion
After the introduction of an nPEP pilot programme in Metro Vancouver, Canada, half of HIV-positive MSM (51.9%) and HIV-negative MSM (48.5%) were aware of nPEP. Use of nPEP was low (3.3%), and all but one person obtained treatments from the nPEP pilot programme. Our study found that nPEP awareness and use were high for a newly established programme when compared with more established programmes in other jurisdictions [9,11,13,14,17]. Our estimates of nPEP awareness are comparable with awareness of TasP in Metro Vancouver, as overall the awareness is similar (nPEP, 45.4%; TasP, 46%) and HIV-positive participants were more likely to be aware of the prevention strategy (nPEP, 51.9%; TasP, 69%) than HIV-negative participants (nPEP, 48.5%; TasP, 41%) [28]. However, compared with other more established prevention strategies, such as HIV testing and condoms, nPEP awareness is comparatively low [3]. MSM who are at risk of HIV infection must be aware of this tool for it to be effective. Overall, our findings highlight the need for increased nPEP services locally and in additional jurisdictions, and promotion of these services by public health bodies, community organizations, and health care providers.
First, clinicians and public health professionals have expressed concerns about the possibility that increasing nPEP availability may result in “risk compensation”, where people may hold a false sense of security and engage in higher risk sexual activities [12,27]. We found that overall use was quite low among both the overall population and participants who reported recent high-risk sex. Encouragingly, our analyses showed that participants who engaged in sexual activities that may increase their risk of HIV transmission were more likely to be aware of nPEP. This included HIV-negative men who recently attended sex parties, had >20 recent male anal sex partners, and used strategic positioning, and HIV-positive participants who had >10 receptive anal sex partners and who did not always have condoms when having sex. Furthermore, our assessments of HIV-negative participants’ attitudes and beliefs showed that those with higher communal sexual altruism or those who believed that they could ask sexual partners to use condoms were more likely to know about nPEP. As these HIV-negative individuals have a greater sense of personal agency and efficacy with regard to HIV prevention, it is plausible that they are more willing to accept nPEP as a part of a combination HIV prevention strategy. However, there are still awareness deficits in HIV-negative participants who could benefit greatly from knowing about nPEP as part of a comprehensive HIV prevention strategy, particularly those who do not believe that they can always get condoms. Although risk compensation should continue to be evaluated as nPEP availability increases, effective individual counselling and tailored public health messaging should help appropriately integrate this tool within combination HIV prevention.
Secondly, the lower level of nPEP awareness in HIV-negative participants, relative to HIV-positive participants, speaks to the need for more targeted and ongoing public health messaging about nPEP as one part of a comprehensive HIV prevention strategy. For HIV-negative men with possible HIV exposure, pre-existing knowledge of this biomedical prevention tool is critical for timely access and optimal treatment effectiveness. Our findings highlight the need for relevant and targeted education, promotion and access to nPEP information for subpopulations of HIV-negative MSM who do not identify as white or as gay, have less formal education, and who live outside the City of Vancouver but in Metro Vancouver. Research has shown that nPEP promotional campaigns in the USA and Australia increased awareness of nPEP by 12-38% [29,32] and could significantly increase intention to use nPEP [33]. Social marketing may be a promising method to improve nPEP awareness, as previous campaigns to promote HIV testing were successful [34]. HIV-positive participants who felt they could not always ask their sexual partners’ HIV status were also less likely to be nPEP aware; this group would benefit from more support in how to communicate about HIV with their sexual partners, and generalized anti-HIV stigma efforts for the overall population. Only a third of all participants talked about nPEP with friends or partners; barriers remain for MSM to discuss this prevention tool openly. This is particularly important because of our finding that over half of HIV-positive participants were nPEP-aware and that there was a statistically significant increase over time. Additionally, we found that HIV-positive participants who ask their partners to disclose their status are more likely to know about nPEP and therefore may be well equipped to recommend it to their HIV-negative partners. So, although HIV-positive MSM would not directly use nPEP, they can talk to their HIV-negative partners about it, which may lead to more open discussions on HIV prevention generally.
Thirdly, primary care clinicians, such as nurse practitioners, registered nurses and physicians, can play an important role in promoting nPEP awareness by taking an opportunistic approach to educate and counsel MSM about nPEP when they access the health care system with evidence of potential risk of HIV transmission. Our univariable analyses showed that HIV-negative participants previously diagnosed with an STI or recently tested for HIV were more likely to be aware of nPEP. MSM should obtain, and may indeed be receiving, nPEP information from clinicians providing HIV and STI testing. However, it is also important for health care providers to proactively discuss HIV prevention strategies with MSM patients during routine visits rather than only within the context of sexual health. Previous studies found that HIV testing or other health care system interactions were associated with greater likelihood of nPEP awareness [13]. Furthermore, previous studies that compared sites with and without established nPEP programmes found that, in the latter, a higher proportion of MSM heard about it from their health care provider [12,13]. Expansion of the current nPEP pilot programme beyond the pilot phase in Metro Vancouver would help to increase the accessibility of this HIV prevention tool for MSM across British Columbia, given the existing structural geographical barriers [2]. In the meantime, health care providers practising outside major urban centres are a crucial link between fostering MSM awareness and timely access to nPEP. One study found that only 39% of respondents who had been tested for HIV were aware of nPEP, indicating a missed opportunity for health care providers to educate their patients about nPEP [13]. Training for health care providers in providing appropriate messaging and counselling to their MSM patients about nPEP as part of a comprehensive HIV prevention strategy is needed. Health care providers can also encourage MSM to talk to partners and friends about nPEP, given this established and rich community-based mechanism for sharing information and improving health literacy.
The nPEP awareness prevalence of 48.5% among HIV-negative participants and 51.9% among HIV-positive participants from this study in Vancouver was higher than estimates from previous studies conducted between 2000 and 2012 in Boston (18.9%), the Netherlands (32.4%), Spain (34.3%), New York City (36.0%), and a combination of US cities (47.5 and 41%) [9,11,13,14,17]. This difference in awareness may be attributable to Vancouver’s recently established nPEP pilot programme and community promotional campaign, whereas most of those cities did not have such a programme or campaign during their study periods. The prevalence of nPEP use from our study was lower than estimates from US studies [11-14], which may reflect better access within STI clinics in US urban centres such as San Francisco [11-13]. Our nPEP use findings were similar to estimates in Spain, where clinical guidelines and recommendations to promote nPEP exist, but structured efforts to promote awareness and use were lacking [14].
The variables we found to be associated with higher nPEP awareness were similar to those in existing literature, including: white race/ethnicity, higher education level, gay identity, higher number of sexual partners, and engagement in higher risk sexual activities [11,13,14]. While some studies found that older age was associated with nPEP awareness [13,15], this was not the case in our study. However, we did find that HIV-negative participants who were currently students, often associated with younger age, were more likely to be nPEP aware. Our significant finding may also be explained by the possibility that current student status may be a proxy for higher literacy levels [30], mediating the effect of age. In terms of substance use, our finding that recent alcohol use was associated with higher nPEP awareness in HIV-negative participants differed from the results of two studies that found no significant association [14,15]. Our findings are encouraging given that alcohol use is commonly associated with greater sexual risk-taking [35]. This association could also be explained by the fact that nPEP promotional materials were made available at bars and nightclubs. Furthermore, while two US studies found significant associations between recreational drug use and nPEP awareness or use [11,12], our study and another in New York City did not find a significant association [13]. Nevertheless, MSM who have sex under the influence of various substances are generally more vulnerable to HIV infection [3,31,32,35], so we must ensure that these subgroups are appropriately informed of the availability and utility of nPEP.
A major strength of this study was its timeliness, as respondents were surveyed in the 15 months following the expansion of a provincially funded nPEP pilot programme that began in July 2012 and was accompanied by a health promotion campaign. Use of RDS methodology instead of the convenience sampling techniques employed by previous studies enabled us to recruit more participants who identified as nonwhite compared with the general population of Canada and Vancouver [3]. Furthermore, unlike other studies with interviewer-conducted surveys [11,13], this study used CASI to decrease the likelihood of social desirability bias in the responses. We stratified by HIV status in our statistical analysis to understand further the differential factors associated with nPEP awareness. We were primarily interested in HIV-negative participants’ awareness of the nPEP intervention given that this is an essential first step to ensuring timely access to treatment. However, the awareness of HIV-positive MSM was also important, as they may inform their partners of this option if HIV transmission is a potential concern.
One limitation of this study was the use of participants’ first response to nPEP awareness questions. Longitudinal analysis of participant’s changes in nPEP awareness over time will help to evaluate the reach of these health promotion programmes and the scale-up of these services to men who may benefit most from this tool. Other limitations include the imbalance of participants by serostatus as there were more HIV-negative participants (n=500) than HIV-positive (n=173), the small sample of HIV-negative participants who used nPEP, and the lack of data on participants’ degree of understanding regarding nPEP effectiveness and attempts to access and use this treatment. Qualitative follow-up with nPEP-aware or -experienced participants will help to provide more nuanced understanding. While our study quantitatively assessed participants’ awareness of nPEP, future qualitative studies could use open-ended questions or focus groups to gain a more precise understanding of the level, and accuracy, of nPEP knowledge.
Future studies should explore how different types of substance use (e.g. injecting, recreational or sex-related drug use) affect nPEP awareness and use, given that past research has obtained conflicting results regarding these relationships [11,13,14]. Additional research is also needed on the most culturally relevant ways to promote nPEP awareness, knowledge and appropriate use to MSM with consideration of existing HIV risk reduction and prevention practices. In the interest of public health priority setting, future studies should assess what the target level of nPEP awareness should be and in which groups. Is a goal of 100% of MSM being nPEP aware appropriate, yet alone realistic, or should promotion focus on subgroups of MSM demonstrating greatest potential for HIV transmission? Finally, while our study found that there was a large awareness gap, there was also a usage gap where very few participants reported using nPEP. Longitudinal follow-up with our participants will identify incident awareness and use of nPEP going forward, allowing us to understand better the gap between awareness and use. Further, exploration of why some nPEP-aware MSM who engage in high-risk sex are not accessing this strategy will also be possible.
This study provided a baseline prevalence of nPEP awareness in the overall population of MSM in Vancouver, BC after the implementation of an nPEP pilot programme to show that awareness and use could be improved, especially among participants at increased risk of HIV acquisition. Further research, programme expansion and health promotion are needed to increase nPEP awareness so that MSM who have been exposed to HIV can access and start the nPEP regimen as soon as possible to reduce their likelihood of HIV infection.
Acknowledgments
grant R01DA031055-01A1
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