31 March 2016 

The deployment of PEP in a Montreal clinic

Doctors and nurses at Montreal’s Clinique médicale l’Actuel provide a range of services related to sexual health, including testing and treatment for HIV and other sexually transmitted infections (STIs). They also provide HIV risk-reduction advice and services for clients through the use of pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP). The clinic receives between 40 and 50 requests for PEP each month.

PEP centres on the use of anti-HIV medicines, taken every day exactly as directed, for 28 consecutive days after a potential exposure to HIV. PEP must be initiated within 72 hours of a possible exposure to HIV.

Doctors at l’Actuel have been providing prescriptions for PEP and related counselling for many years. When they recently reviewed their clinic’s database they found that they had amassed health-related information from several thousand PEP users. In analyzing their database, they found that a regimen that included the fixed-dose combination of tenofovir + FTC (sold as Truvada) was well tolerated and that patients reported that they generally adhered well to PEP regimens. Likely cases of HIV infection due to PEP failure were very rare—less than 1%.

The PEP process

L’Actuel has been providing services related to PEP from the year 2000.

At l’Actuel, when a person seeks help due to a potential HIV exposure, they are interviewed by a nurse and assessed so that healthcare personnel can determine the level of risk that occurred. The person also undergoes rapid HIV testing for HIV antibodies and a test for a protein called p24, which is produced by HIV-infected cells. If the person’s sexual partner(s) is at this consultation, the partner is also offered testing and counselling. A physician examines the patient and, depending on the degree of risk exposure that has occurred, offers PEP and counselling about its use. People who take PEP are advised to take it every day, exactly as directed, for 28 consecutive days.

Following the initial PEP consultation, the clinic books several appointments for monitoring and counselling over the next three months.

For the present analysis, researchers focused on 3,547 visits to the clinic for consultation about PEP. These visits took place between October 2000 and July 2014.

Who sought PEP?

The average profile of participants who sought PEP was as follows:

  • 92% men, 8% women
  • the majority (83%) of men who sought PEP did so because of potential exposure from high-risk sex with another man
  • age – 35 years
  • 43% of the men were “intoxicated” at the time of their potential exposure to HIV; the source/cause of the intoxication was not stated
  • 70% of the men sought PEP for the first time
  • in 67% of all cases, participants did not know the HIV status of their sexual partner(s)
  • in 81% of all cases, medical personnel assessing the participant concluded that the participant was at moderate-to-high risk for HIV infection


A total of 2,772 participants received prescriptions for PEP. Such prescriptions were mostly a combination of two nucleoside analogues (commonly called nukes) and a third agent, either Kaletra (lopinavir-ritonavir) or raltegravir (Isentress).

The nuke regimens commonly prescribed were as follows:

  • Truvada (tenofovir + FTC)
  • Combivir (AZT + 3TC)

In 96% of cases where PEP was prescribed, medical personnel judged the person’s risk of exposure to be moderate to high.

Of the 2,772 participants prescribed PEP, 41 prematurely stopped taking PEP because the person with whom they had unprotected intercourse later tested negative for HIV.

Among the remaining 2,731 participants, here is how their medication-taking habits were distributed (when information on this was available):

  • 69% took all medicines exactly as prescribed
  • 16% stopped coming to the clinic
  • 8% did not have sufficient information in their file
  • 4% discontinued PEP
  • 2% disclosed that they missed more than five doses
  • 1% changed regimens

The main reason that participants prematurely stopped taking PEP or changed their regimen was due to side effects.

Participants who were taking a Truvada-based regimen were more likely to be adherent than participants who took a Combivir-based regimen.

Towards the study’s later years, the combination of Truvada + raltegravir was more frequently prescribed for PEP. This regimen was generally well tolerated and is the regimen in common use for PEP at the clinic today (Nimâ Machouf, PhD, written communication).

In general, the researchers found that the following categories of people were more likely to be adherent to PEP:

  • those taking it for the first time
  • older patients
  • men

HIV infection

As there have not been large well-designed clinical trials comparing the risk of HIV infection in PEP users compared to no PEP, researchers cannot be certain about its effectiveness. However, results from studies with monkeys susceptible to a virus called SIV (simian immunodeficiency virus) and observational studies in people at high risk for HIV infection are all highly suggestive that PEP can significantly reduce this risk when taken within 72 hours of exposure, exactly as directed, for 28 consecutive days.

During the study period, 11 participants who sought PEP became infected with HIV. Of these participants, one did not receive PEP because the person to whom he was exposed was “presumed to be HIV negative,” according to the researchers. This leaves 10 potential cases of PEP failure. However, when these 10 cases were investigated, nine of them continued to have high-risk sexual behaviour—mainly receptive condomless anal intercourse—following prescription of PEP. Note that PEP is not meant to confer protection from ongoing exposure(s) to HIV. Therefore, the researchers concluded that only one case of infection in this study could truly be considered to have possibly arisen from PEP failure. This would be one case out of 2,731 PEP users (0.04%), which is a very low rate of PEP failure (if indeed PEP failure did occur).

Doctors at a large sexual health clinic in Boston recently reviewed their prescriptions of PEP and their database of clients who sought related services over a three-decade period. They found that more than 50% of PEP users had mental health issues. They also found that if HIV infections did occur among PEP users, such infections tended to occur well after the 28-day course of PEP had been completed. This latter result would indicate that high-risk exposures to HIV were ongoing.

The findings from the Boston review support the results from the l’Actuel researchers on the beneficial effect of PEP in reducing the risk of HIV infection.

Both the Boston and Montreal researchers suggested that for patients with ongoing high-risk exposures to HIV, prescription of PrEP should be considered.

The report from l’Actuel is important and will hopefully stimulate other major clinics in high-income countries to track and analyse the results of their patients who use PEP.

Note on access

PEP is expensive—the monthly cost can range from about $1,000 to $2,000, depending on the regimen chosen. The cost of PEP in cases where HIV exposure has occurred via consensual intercourse is not covered in all regions. Speak to a doctor, nurse or pharmacist for more information in your region.


Post-exposure prophylaxis (PEP) ­– CATIE fact sheet

High rate of mental health issues found among some PEP usersCATIE News

The PEP ProgramProgramming Connection case study

Can we prevent infection with HIV after an exposure? The world of post-exposure prophylaxis (PEP)Prevention in Focus

Guide pour la prophylaxie après une exposition au VIH, au VHB et au VHC dans un contexte non professionnel : Résumé – Ministère de la Santé et des Services sociaux du Québec

—Sean R. Hosein


  1. Thomas R, Galanakis C, Vézina S, et al. Adherence to post-exposure prophylaxis (PEP) and incidence of HIV seroconversion in a major North American Cohort. PLoS One. 2015 Nov 11;10(11):e0142534.
  2. Jain S, Oldenburg CE, Mimiaga MJ, et al. High levels of concomitant behavioral health disorders among patients presenting for HIV non-occupational post-exposure prophylaxis at a Boston community health center between 1997 and 2013. AIDS and Behavior. 2015.
  3. Henderson DK, Gerberding JL. Prophylactic zidovudine after occupational exposure to the human immunodeficiency virus: an interim analysis. Journal of Infectious Diseases. 1989 Aug;160(2):321-7.