Adherence to Post-Exposure Prophylaxis (PEP) and Incidence of HIV Seroconversion in a Major North American Cohort.

There is limited evidence on the efficacy of post-exposure prophylaxis (PEP) for sexual exposures. We sought to determine the factors associated with adherence to treatment and describe the incidence of PEP failures in a Montreal clinic.We prospectively assessed all patients consulting for PEP following sexual exposures from October 2000 to July 2014. Patients were followed at 4 and 16 weeks after starting PEP. Treatment adherence was determined by self-report at week 4. Multivariable logistic regression was used to estimate the factors predicting adherence to treatment.3547 PEP consults were included. Patients were mainly male (92%), MSM (83%) and sought PEP for anal intercourse (72%). Seventy-eight percent (n = 2772) of patients received a prescription for PEP, consisting of Tenofovir/Emtracitabine (TVD) + Lopinavir/Ritonavir (LPV) in 74% of cases, followed by Zidovudine/Lamivudine (CBV) + LPV (10%) and TVD + Raltegravir (RAL) (8%). Seventy percent of patients were adherent to treatment. Compared to TVD+LPV, patients taking CBV+LPV were less likely to adhere to treatment (OR 0.58, 95% CI 0.44-0.75), while no difference was observed for patients taking TVD+RAL (OR 1.15, 95% CI 0.83-1.59). First-time PEP consults, older and male patients were also more adherent to treatment. Ten treated patients seroconverted (0.37%) during the study period, yet only 1 case can be attributed to PEP failure (failure rate = 0.04%).PEP regimen was associated with treatment adherence. Patients were more likely to be adherent to TVD-based regimens. Ten patients seroconverted after taking PEP; however, only 1 case was a PEP failure as the remaining patients continued to engage in high-risk behavior during follow-up. One month PEP is an effective preventive measure to avoid HIV infection

Patient and exposure characteristics (N = 3547).

<p>* Among sources which are known to patients (n = 1184).</p><p>Patient and exposure characteristics (N = 3547).</p

PEP regimen prescribed (N = 2772).

<p>TVD: Truvada (tenofovir-emtricitabine), CBV: Combivir (zidovudine-lamivudine), LPV: lopinavir/ritonavir, RAL: raltegravir.</p><p>PEP regimen prescribed (N = 2772).</p

Characteristics of seroconverted cases (N = 11).

<p>Characteristics of cases with documented seroconversion. Delay denotes consultation delay following the sexual exposure. URAI: Unprotected receptive anal intercourse. UIAU: Unprotected insertive anal intercourse. W0-W24: HIV test results from week 0 to week 24. Neg: HIV-negative test result. POS: HIV-positive test result. Missing information was left blank.</p><p>Characteristics of seroconverted cases (N = 11).</p

Factors associated with adherence to PEP regimen (N = 2731).

<p>*Univariate odds ratio</p><p>**Adjusted odds ratio</p><p>Multivariable logistic regression model of adherence to PEP regimen.</p><p>Factors associated with adherence to PEP regimen (N = 2731).</p