Transitioning to HIV Pre-Exposure Prophylaxis (PrEP) from Non-Occupational Post-Exposure Prophylaxis (nPEP) in a Comprehensive HIV Prevention Clinic: A Prospective Cohort Study

Abstract

The uptake of pre-exposure prophylaxis (PrEP) for HIV prevention remains low. We hypothesized that a high proportion of patients presenting for HIV non-occupational post-exposure prophylaxis (nPEP) would be candidates for PrEP based on current CDC guidelines. Outcomes from a comprehensive HIV Prevention Clinic are described. We evaluated all patients who attended the HIV Prevention Clinic for nPEP between January 1, 2013 and September 30, 2014. Each patient was evaluated for PrEP candidacy based on current CDC-guidelines and subjectively based on physician opinion. Patients were then evaluated for initiation of PrEP if they met guideline suggestions. Demographic, social, and behavioral factors were then analyzed with logistic regression for associations with PrEP candidacy and initiation. 99 individuals who attended the nPEP clinic were evaluated for PrEP. The average age was 32 years (range, 18–62), 83 (84%) were male, of whom 46 (55%) men who had have sex with men (MSM). 31 (31%) met CDC guidelines for PrEP initiation, which had very good agreement with physician recommendation (kappa=0.88, 0.78–0.98). Factors associated with PrEP candidacy included sexual exposure to HIV, prior nPEP use, and lack of drug insurance (p<0.05 for all comparisons). Combining nPEP and PrEP services in a dedicated clinic can lead to identification of PrEP candidates and may facilitate PrEP uptake. Strategies to ensure equitable access of PrEP should be explored such that those without drug coverage may also benefit from this effective HIV prevention modality.

Introduction

HIV is a major global heath concern with more than 2 million new HIV infections per year worldwide.¹ Effective HIV prevention strategies include behavioral interventions,² barrier protection,³ circumcision,⁴ HIV case finding,⁵ and treatment as prevention.⁶ In addition, post-exposure prophylaxis (PEP) following HIV exposures has long been used as an effective prevention modality, based on well-designed observational studies.^7
–9 PEP is used in both occupational (oPEP) and non-occupational (nPEP) settings and is most effective when initiated within 72 h of exposure.¹⁰ Because PEP is used reactively rather than proactively, and given the challenges with identifying high-risk exposures¹¹ and the associated poor adherence to ART and clinic appointments,¹² PEP alone is not a sufficient HIV-prevention tool and is unlikely to have major impact the incidence of HIV at the population level.¹³

Pre-exposure prophylaxis (PrEP) is a proactive HIV prevention strategy where ART is initiated prior to HIV exposures, and is gaining increasing attention in the effort to decrease the global burden of HIV. PrEP has demonstrated efficacy for reducing rates of HIV transmission in persons at high-risk of HIV acquisition, including men who have sex with men (MSM),¹⁴ injection drug users (IDU),¹⁵ and people engaging in heterosexual sex.^16,17 Despite these advances, uptake of PrEP has been slow.^18,19

Many individuals presenting to medical attention for HIV nPEP care are likely to be at high risk of acquiring HIV beyond the presenting incident. This study seeks to evaluate PrEP eligibility and uptake in individuals who presented for nPEP care at a novel, comprehensive HIV Prevention Clinic in Toronto, Canada.

Methods

The aim of this prospective observational cohort study was to evaluate demographic features and predictive variables for PrEP candidacy (based on interim CDC guidance²⁰ to May 2014 and current CDC guidelines²¹ thereafter) and PrEP usage in individuals who initially presented for nPEP care. This study was approved by the Research Ethics Board at the University Health Network in Toronto, Canada.

Clinic description and inclusion criteria:

All patients who attended their first appointment at the HIV Prevention Clinic for nPEP between January 1, 2013 and September 30, 2014 were included in the study. We designed a dedicated HIV Prevention Clinic at the University Health Network (Toronto General Hospital site) that offers comprehensive care for those at risk of HIV acquisition. This interdisciplinary clinic provides nPEP and PrEP care in addition to counseling regarding safer sexual practices, nursing, pharmacy, and psychiatric and social work support. The clinic receives referrals from three local Emergency Departments (Toronto General, Toronto Western, and Mount Sinai Hospitals; all in Toronto, ON), in addition to referrals from primary care and sexual health clinics throughout Toronto. Standardized protocols are in place at participating hospitals to initiate nPEP care when appropriate, and perform requisite baseline blood work. Patients are then referred to the HIV Prevention Clinic and seen by a board-certified Infectious Diseases consultant with expertise in HIV care within 3–5 days.

Patients presenting to the emergency department or primary care clinic within 72 h of an HIV exposure deemed to benefit from nPEP were given a standard ART ‘starter pack’ typically consisting of co-formulated tenofovir and emtricitabine (TDF/FTC) plus raltegravir (RAL) for use until they could be seen at the HIV Prevention Clinic. At the initial visit, a comprehensive medical assessment was performed and the events surrounding the exposure were elucidated in detail. The risk of HIV seroconversion was estimated and nPEP was either continued for a total of 28 days, or stopped, based on guidelines, clinical discretion, and patient values.

Patients were also screened for other communicable infections (e.g., hepatitis B, hepatitis C, sexually transmitted infections), pregnancy, and vaccinated as required (e.g., hepatitis B, tetanus). Patients were seen in follow-up 1–2 weeks after their first visit to assess tolerability and adherence of nPEP, then offered appointments at 4–6 weeks, 3 months, and 6 months following the initial visit for repeat HIV and sexually transmitted infection screening, follow-up of vaccination, and safe sexual practices counseling. The HIV Prevention Clinic also provided ongoing care for patients at high-risk of HIV acquisition beyond the 6-month examination. In addition, the same services were provided for individuals who fell outside of the 72-h window for nPEP and did not initiate ART preventative care. All who presented for nPEP care were screened for consideration of PrEP during the medical history at every clinic appointment based on CDC guidelines for eligibility.²¹

Variables

All information was recorded prospectively into a dictated clinic note based on a standardized template, which included all variables in the study. The information was then recorded into a database. Demographic and behavioral variables were self-reported and recorded by the physician after a structured clinical encounter. An infectious diseases specialist adjudicated whether each patient met CDC guideline-criteria for initiating PrEP.¹⁴ The physician who saw the patient also explicitly recorded whether he or she thought the patient would benefit from PrEP based on clinical experience, regardless of what the guidelines suggested.

Patients were considered PrEP candidates if they met CDC guideline criteria at their first or second clinic appointment. Sexual indications for PrEP included an ongoing relationship with an HIV-positive partner, infrequent use of condoms with one or more sexual partners of unknown HIV serostatus at substantial HIV risk, and MSM with a sexually transmitted infection within the past 6 months. PrEP criteria for IDUs was defined as any sharing of injection equipment in the past 6 months or having been in a methadone, buprenorphine, or suboxone treatment program in the past 6 months.

The HIV Prevention Clinic provided ongoing care overseeing PrEP for those patients choosing to initiate it. PrEP was started in eligible patients with negative HIV serology 4 months after their most recent HIV exposure, and with no signs or symptoms of an acute HIV seroconversion illness. In select individuals deemed to be at very high risk for HIV acquisition, PrEP was initiated 2 months after the most recent exposure if there were no signs or symptoms of acute HIV seroconversion and with a negative HIV serology and negative HIV RNA PCR.

Data analysis

All analyses were conducted using SPSS version 22.0 (IBM, Armonk, New York). Significance was defined as p<0.05. Adjusted analyses were conducted with multinomial logistic regression, controlling for age, sex, and race (white vs. non-white) when evaluating predictive factors for meeting PrEP guidelines and for age only when evaluating PrEP uptake, because of a fewer number of patients. The analysis of patients initiating PrEP was limited to those who ultimately initiated PrEP or who met CDC guidelines to initiate PrEP. Co-variables were chosen a priori. Patients with missing data were excluded from the analyses. Fisher exact p-values were used for 2×2 comparisons, while Pearson's chi-squared was used for larger comparisons. Kappa was used to quantify agreement and 95% confidence intervals (CIs).²² The attributable risk of a confounder was calculated by dividing the difference between unadjusted and adjusted odds ratios by the unadjusted odds ratio between two variables.

Results

Between January 1, 2013 and September 30, 2014, 125 patients were seen at the HIV Prevention Clinic for nPEP referrals. Ninety-nine (79%) patients attended at least two clinic visits or disclosed sufficient information on the first visit to assess whether they were candidates for PrEP. The average age was 32 years (range, 18–62), 65 (66%) patients were white, and 83 (84%) were male, of whom 46 (55%) were known to be MSM.

Thirty-one patients (31%) met established CDC guidelines for PrEP initiation. There was very good agreement between CDC guideline recommendation and physician recommendation for PrEP candidacy [kappa=0.88, 95% confidence interval (CI) 0.78–0.98]. Patients presenting for PEP who did not meet CDC guideline criteria for PrEP were deemed to have either no or minimal risk for HIV acquisition beyond the event for which they were seeking PEP care.

Results of a logistic regression analysis for PrEP candidacy can be viewed in Table 1. Sex, age, or race did not significantly predict PrEP candidacy. The strongest predictor of PrEP candidacy was sexual exposures compared to non-sexual HIV exposures (p=0.003); all PrEP candidates (n=26) presented for nPEP following a sexual exposure. Other significant independent predictors for PrEP candidacy included MSM (AOR 16, 95% CI: 1.9–138) and prior use of nPEP in the past 2 years (AOR 28, 95% CI: 3.0–250). Significantly fewer PrEP candidates than non-candidates had qualifying medication insurance (62% vs. 84%; p=0.046).

Table 1.

Variables Associated with PrEP Candidacy as Per CDC PrEP Guidelines in Patients Who Presented for HIV nPEP

	PrEP candidate (n=31)	Not PrEP candidate (n=68)	p Value	AOR (95% CI)
Sex, male	29/31 (94)	54/68 (79)	0.087	4.0 (0.83–18.91)
Age, avg (SD)	30.7 (8.4)	32.4 (10.3)	0.43	0.98 (0.93–1.03)
Race, white (vs. non-white)	18/31 (58)	47/68 (69)	0.36	0.65 (0.27–1.61)
Sexual exposure (vs. non-sexual)	26/26 (100)	48/67 (72)	0.001	Non-calculable
Prior PEP past 2 years	8/30 (27)	1/67 (1.5)	<0.001	27.78 (3.07–250.00)
Drug insurance	16/26 (62)	47/56 (84)	0.046	0.35 (0.11–1.06)
HIV-positive exposure source (vs. unknown serostatus)	13/26 (50)	22/47 (33)	0.16	1.77 (0.68–4.65)
Non-consensual exposure^a	0/26 (0)	4/48 (8.3)	0.29	Non-calculable
Barrier protection initially used^a	11/25 (44)	21/45 (47)	1	0.76 (0.27–2.14)
MSM^b	22/23 (96)	24/40 (60)	0.003	16.30 (1.93–137.90)
Exposure route^b
Vaginal	1 (4.2)	16 (38)		0.02 (0.00–0.27)
Anal	14 (58)	19 (45)		0.30 (0.06–1.42)
Oral	1 (4.2)	3 (7.1)		0.08 (0.01–1.42)
Multiple	8 (33)	4 (9.5)	0.006	Reference
Sexual practices (MSM only)
Insertive and receptive	6 (27)	5 (22)		3.09 (0.58–16.40)
Receptive	10 (46)	6 (26)		3.90 (0.87–17.55)
Insertive	6 (27)	12 (52)	0.22	Reference
Completed PEP
Yes	18 (86)	38 (68)
No	1 (4.8)	3 (5.4)
PEP not indicated	2 (9.5)	15 (27)	0.25
PrEP discussed	28/30 (93)	13/68 (19)	<0.001	64.3 (12.8–322.9)
Physician recommended PrEP	27/30 (90)	2/68 (2.9)	<0.001	297.3 (44.1–2004.0)
Patient expressed some interest in PrEP^c	20/28 (71)	1/9 (11)	0.002	19.96 (1.78–224.26)
PrEP initiated	11/30 (37)	1/68 (1.5)	<0.001

Adjusted for sex, age, and race (white vs. non-white) unless otherwise specified.

Sexual exposure only.

Males with sexual exposure only.

Of patients where PrEP was discussed.

At the time of writing, PrEP was initiated in 12 (12%) individuals; 11 (92%) met CDC guideline criteria. All 11 patients were MSM (Table 2). The one patient who did not meet guideline criteria had engaged in unprotected receptive anal intercourse, was not currently sexually active due to injury, but planned to resume high-risk sexual behavior after recovery. Given that he was not currently sexually active, he was not felt to meet CDC guideline criteria for PrEP at the time of his clinic appointment by the clinician.

Table 2.

Predictors for Initiating HIV PrEP in Patients Who Presented to an HIV Prevention Clinic for nPEP

	PrEP initiated	PrEP not initiated	Unadjusted p value	AOR (95% CI)
Sex (% male)	11/12 (92)	18/19 (95)	1	0.48 (0.03–9.01)
Age	34.3 (7.8)	29.0 (8.2)	0.086	1.09 (0.99–1.20)
Race (% white) vs. non-white	10/12 (83)	8/19 (42)	0.032	5.01 (0.77–32.80)
Medication insurance	7/9 (78)	9/17 (53)	0.40	2.11 (0.30–15.17)
Prior PEP past 2 years	3/11 (27)	5/19 (26)	1	1.28 (0.21–7.63)
HIV-positive source patient vs. unknown serostatus	3/7 (43%)	9/18 (50%)	1	0.75 (0.13–4.44)
Barrier protection used	3/7 (43)	7/17 (41)	1	1.07 (0.18–6.51)
MSM^a	6/6 (100)	15/16 (94)	1	Not calculable
Sexual practices (MSM only)
Insertive and receptive	3 (43)	3 (20)		0.45 (0.04–4.82)
Receptive	2 (29)	8 (53)		2.28 (0.20–25.77)
Insertive	2 (29)	4 (27)	0.46	Reference
Completed PEP
Yes	7 (100)	11 (79)		–
No	0	1 (7.1)		–
PEP not indicated	0	2 (14)	0.42	–

All patients presented because of a sexual exposure. Model is adjusted for age.

Males with sexual exposure only.

Results of a logistic regression analysis for PrEP initiation can be viewed in Table 2. Of PrEP candidates, non-white patients (20%) were significantly less likely than white patients (56%) to initiate PrEP in the unadjusted analysis (p=0.032). However, the difference was no longer significant after adjusting for age, which explained 27% of the decreased odds of receiving PrEP among non-whites. There was a trend towards older age for initiating PrEP among candidates (odds ratio=1.09, CI 0.99–1.20 per additional year). No other variable significantly predicted PrEP initiation among candidates in our population.

Discussion

PrEP is an effective yet under utilized HIV prevention modality. In our dedicated HIV Prevention Clinic, 31% of individuals referred for nPEP care met CDC guideline criteria for PrEP. All patients who qualified for PrEP as per prior interim guidelines also qualified retrospectively according to current guideline criteria. At the time of writing, only 37% of those who met criteria had initiated this HIV prevention modality. A concerning finding is that significantly fewer PrEP candidates had qualifying medication insurance compared to non-candidates.

The cascade of PrEP care describes the sequential barriers along the pathway of initiating PrEP, and is akin to the cascade of HIV care between all HIV-positive persons and those with suppressed viral loads.²³ Each step between presenting for nPEP and subsequent PrEP initiation can be targeted in order to increase PrEP uptake in suitable candidates, with the ultimate goal of reducing HIV acquisition and further viral transmission in the community. The full cascade of PrEP care starts well before an individual comes into contact with medical professionals. Individuals must first recognize their high risk of HIV acquisition and then seek medical advice regarding HIV prevention. Patient education and buy-in to PrEP benefits is vital, and is followed by overcoming logistics to initiate and maintain PrEP on suitable candidates. While we describe a specific high-risk population at our HIV Prevention Clinic, patients receiving nPEP likely represent only a minority of patients who would benefit from PrEP.

Patients presenting for nPEP care are uniquely suited as having a higher likelihood of initiating PrEP, as they have typically overcome the initial psychological barriers of recognizing that an HIV exposure has occurred and have already made an effort to seek medical care. Therefore, linking nPEP, PrEP, and behavioral interventions in a comprehensive HIV Prevention Clinic may be an ideal and practical solution for many people at high risk for HIV acquisition. Engaging patients presenting for nPEP care in a dedicated, interdisciplinary HIV Prevention Clinic may allow for a smooth transition from nPEP to PrEP care. This population may be more likely benefit from PrEP given that they have had at least one high-risk exposure to be seen in clinic and at-risk individuals can be easily identified.

In addition, our dedicated HIV Prevention Clinic serves the local community for primary PrEP referrals such that those at high-risk for HIV acquisition can be linked to care proactively, rather than after a significant HIV exposure. Moreover, concentrating expert services for HIV prevention in a single clinic may optimize the impact of co-interventions and interdisciplinary care (e.g., social work, psychiatry, HIV nursing, pharmacy) addressing underlying risks for HIV acquisition. Comprehensive HIV prevention clinics overcome barriers among community healthcare providers with varied knowledge and comfort prescribing PrEP.²⁴ This approach also encourages the establishment of nonjudgmental relationships with the patients and may encourage further PrEP uptake.²⁵

Our approach is to transition from nPEP to PrEP in eligible patients as soon as possible when safe to do so. There is some theoretical concern that PEP may delay HIV seroconversion and subsequent PrEP initiation could lead to drug resistance in those who seroconvert. This should be balanced by taking into account an individualized risk assessment for each patient, and the urgency of PrEP initiation. In those deemed to be very high risk for HIV acquisition, we confirmed that there were no signs or symptoms of an acute HIV seroconversion illness, and had evidence of negative HIV serology and negative HIV PCR 2 months from their most recent HIV exposure prior to initiating PrEP.

Variables associated with PrEP candidacy in our population who presented for nPEP care included prior use of nPEP, MSM, and presenting to care because of a high-risk sexual exposure. While this is an opportunity to reduce the risk of HIV acquisition in the local MSM population, outreach to other high-risk populations such as people who use injection drugs and female sex-trade workers should be scaled up to ensure maximum uptake for those in need.

Worrisome is that candidacy for PrEP was associated with not having drug insurance coverage. At the current price of approximately $13,000 USD per year, TDF/FTC is prohibitively expensive for the vast majority of individuals without drug insurance.²⁶ While a higher proportion of PrEP candidates with drug insurance initiated PrEP compared to those without drug insurance, the difference did not reach significance. This may partly be due to the expertise and dedication of the interdisciplinary care providers in obtaining alternative sources of funding for PrEP delivery. However, our study was not powered to detect small or moderate differences in PrEP uptake between insured and non-insured patients. Efforts should now be focused on ensuring equitable access to PrEP care, which will improve uptake among those at highest risk.²⁷

Our study is limited in that missing data from some patients, especially those who did not attend their subsequent clinic appointments, may limit generalizability to greater nPEP patient populations. Our clinic setting is within a large urban center in a developed country and this cohort may not be representative of those from developing countries or other urban centers in developed countries. Our study was also limited by small sample sizes and therefore was not powered to detect small differences in factors associated with PrEP uptake.

Combining nPEP and PrEP care in a dedicated HIV Prevention Clinic is an effective way of identifying PrEP candidates as many meet criteria for this primary HIV prevention modality. A major barrier to PrEP initiation is the lack of drug coverage among suitable candidates.

Footnotes

Author Disclosure Statement

The authors have no financial conflicts of interest.

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