Pre-Exposure Prophylaxis to Prevent HIV-1 Acquisition Within HIV-1 Discordant Couples (Partners PrEP)

• Incidence of HIV-1 Seroconversion Among HIV-1 Uninfected Participants [ Time Frame: Up to 36 months ] [ Designated as safety issue: No ]
  The efficacy of once daily PrEP in preventing HIV-1 acquisition among uninfected heterosexuals in HIV-1 discordant partnerships, measured by calculating the HIV incidence per 100 person-years in each of three arms.
  
  
• Number of Participants With Serious Adverse Events (SAEs) [ Time Frame: Up to 36 months ] [ Designated as safety issue: Yes ]
  Safety of daily TDF or FTC/TDF among HIV-1 uninfected individuals randomized to TDF or FTC/TDF compared to those randomized to placebo measured as the number of participants with Serious Adverse Events (SAEs) during follow-up.
  
  

• Study Drug Adherence: Total Number of Study Drug Doses Taken of the Total Dispensed Doses. [ Time Frame: Up to 36 months ] [ Designated as safety issue: No ]
  Adherence to study medication as assessed by pill count at follow-up visits. We assessed the total number of doses taken of the total dispensed doses.
  
  
• Study Drug Adherence: Self-reported Missed Doses of Study Drug [ Time Frame: Up to 36 months ] [ Designated as safety issue: No ]
  Adherence to study drug measured as the percentage of visits when participants reported missing 1) any dose of study drug in the prior month and 2) 2 or more consecutive doses of study drug.
  
  
• Number of Seroconverters With an HIV-1 Mutation Conferring Resistance to TDF or FTC [ Time Frame: Up to 36 months ] [ Designated as safety issue: Yes ]

  HIV-1 resistance as measured by the number of seroconverters who had an HIV-1 reverse transcriptase mutation (K65R, K70E, M184I, or M184V) conferring resistance to TDF or FTC. These mutation types were pre-defined. Plasma samples for resistance testing were collected at the visit seroconversion was first detected and again at a visit within 1 month of seroconversion. Mutations detected at either of those visits are reported.

  Both seroconverters found to have a resistance mutation had been HIV infected at enrollment (TDF arm: n=1; FTC-TDF arm: n=1).

  
  
• Number of Participants With a Sexually Transmitted Infection (STI) During Follow-up [ Time Frame: Up to 36 months ] [ Designated as safety issue: No ]

  Prevalence of STIs measured as the number of participants with a positive test result for N. gonorrhoeae, C. trachomatis, or T. vaginalis during follow-up. Participants were tested for STIs at annual follow-up visits and at intervening visits at which the participant presented with symptoms of an STI. Assessment for symptomatic sexually transmitted infections was conducted quarterly.

  N. gonorrhoeae and C. trachomatis testing were by APTIMA Combo 2 (Gen-Probe) or COBAS Amplicor (Roche Diagnostics). T. vaginalis testing was by APTIMA TV TMA (Gen-Probe) or In Pouch TV (Biomed Diagnostics).

  
  
• Prevalence of Unprotected Sex During Follow-up [ Time Frame: Up to 36 months ] [ Designated as safety issue: No ]
  Sexual risk behavior of participants, measured as the percentage of visits when participants reported having unprotected sex during follow-up.
  
  
• Congenital Abnormalities Among Infants Born to Female Participants Taking Study Drug. [ Time Frame: Up to 36 months ] [ Designated as safety issue: Yes ]
  Infant outcomes measured as the number of live-born infants born to female participants taking study drug that had any congenital anomalies.
  
  
• Length Among Infants Born to Female Participants Taking Study Drug [ Time Frame: up to 12 months ] [ Designated as safety issue: Yes ]
  The slope of the linear model of the growth of infants (length) during the entirety of follow-up. The length of the infant was measured as a z-score, in terms of standard deviations from the age and gender specific median using the World Health Organization growth curve, accounting for skewness. The slope, representing the change over time of the z-score, was calculated using all available z-scores over 12 months and regressing against study month.
  
  
• Weight Among Infants Born to Female Participants Taking Study Drug [ Time Frame: up to 12 months ] [ Designated as safety issue: Yes ]
  The slope of the linear model of the growth of infants (weight) during the entirety of follow-up. The weight of the infant was measured as a z-score, in terms of standard deviations from the age and gender specific median using the World Health Organization growth curve, accounting for skewness. The slope, representing the change over time of the z-score, was calculated using all available z-scores over 12 months and regressing against study month.
  
  
• Head Circumference Among Infants Born to Female Participants Taking Study Drug [ Time Frame: up to 12 months ] [ Designated as safety issue: Yes ]
  The slope of the linear model of the growth of infants (head circumference) during the entirety of follow-up. The head circumference of the infant was measured as a z-score, in terms of standard deviations from the age and gender specific median using the World Health Organization growth curve, accounting for skewness. The slope, representing the change over time of the z-score, was calculated using all available z-scores over 12 months and regressing against study month.
  
  

HIV-1 uninfected individuals within HIV-1 discordant partnerships are at high-risk for HIV-acquisition. The majority of HIV-1 transmissions to adults in Africa occur within stable, HIV-1 discordant couples.

Pre-exposure chemoprophylaxis, in which an HIV-1 uninfected individual at high risk for contracting HIV-1 takes antiretroviral medications to maintain blood and genital drug levels sufficient to prevent HIV-1 acquisition, has been proposed as a potential HIV-1 prevention strategy.

This study was a randomized, blinded, placebo-controlled trial to demonstrate if pre-exposure prophylaxis decreases HIV-1 acquisition among HIV-1 uninfected individuals within HIV-1 discordant couples. The HIV-1 uninfected partner was randomized in a 1:1:1 ratio to one of three arms: once daily Tenofovir Disoproxil Fumarate (TDF), Emtricitabine/Tenofovir Disoproxil Fumarate (FTC/TDF) or Placebo.

Couples were followed up to 36 months; the HIV uninfected partner attended monthly visits and the HIV infected partner quarterly visits. All participants received a comprehensive package of HIV prevention services including individual and couples counseling, free condoms, and male circumcision referrals.

Participants who seroconverted during follow-up stopped the study drug but continued with follow-up.