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Impact of the Daily Doxycycline Pre-exposure Prophylaxis (PrEP) on the Incidence of Syphilis, Gonorrhoea and Chlamydia (Syphilaxis)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT03709459
Recruitment Status : Recruiting
First Posted : October 17, 2018
Last Update Posted : April 1, 2022
South Australian Health and Medical Research Institute
Monash University
Information provided by (Responsible Party):
Kirby Institute

Brief Summary:

1. This study is a non-randomized observational cohort trial using before and after comparison to evaluate intervention 2. It would mimic the conditions that would occur outside a clinical trial. 2. After consent and enrolment, all procedures will be guided by the Australian STI Management Guidelines.

3. All enrolling participants will be offered daily doxycycline 100mg 4. All participants will be invited to complete a survey in every 3 months time for 12 months dated from participation.

5. All follow-up information will be collected through electronic data capture to allow accurate and timely analyses.

6. Data collection will be from (i) medical records (ii) online self-completed questionnaire

Condition or disease Intervention/treatment
STIs Prevention Drug: Doxycycline

Detailed Description:

The last decade has seen increasing rates of bacterial STIs in Australia in gay and bisexual men in particular. Although STIs are easy to diagnose and treatment is effective, untreated STIs can cause significant health issues.

Previous research has shown that taking two100mg doxycycline tablets within 24 hours of sex as prophylaxis reduces syphilis and chlamydia significantly. Also a pilot trial conducted in the US suggested that using 100mg doxycycline as prophylaxis reduced the incidence of gonorrhoea, syphilis and chlamydia. Thus the question of whether taking doxycycline daily in high risk population would reduce the rate of STIs arose.

We set up this study as a non-randomized observational cohort trial using a before and after comparison to evaluate if taking 100mg doxycycline daily would help high risk gay and bisexual men to reduce the possibility of acquiring gonorrhoea, syphilis and chlamydia. Our primary objectives are to:assess acceptability of a daily dosing regimen for doxycycline prophylaxis, and measure the efficacy of 100mg daily doxycycline STI prophylaxis against reinfection with gonorrhoea, chlamydia and syphilis. Our secondary objectives are to: describe patterns of doxycycline use and medication adherence to the recommended schedule participants; evaluate change in behavioral among all study participants; evaluate resistance in the gut microbiota and in those colonized by S aureus at baseline and end of study, in a subset of consenting participants.

The study will be conducted in 3 sexual health centres. Eligible participants will undergo standard care in their trimonthly visit recommended by STI testing guideline, and complete informed consent and a baseline survey. They will be given daily dose of 100mg oral doxycycline for 3 months during the visit, and instruction of how to take the medicine. Questionnaires will be sent out to participants in every 3 months electronically and data will be collected and stored directly into the study survey database. Each participant will be follow-up for 12 months.

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Study Type : Observational [Patient Registry]
Estimated Enrollment : 125 participants
Observational Model: Cohort
Time Perspective: Prospective
Target Follow-Up Duration: 12 Months
Official Title: Impact of the Daily Doxycycline Pre-exposure Prophylaxis (PrEP) on the Incidence of Syphilis, Gonorrhoea and Chlamydia
Actual Study Start Date : December 17, 2019
Estimated Primary Completion Date : December 17, 2024
Estimated Study Completion Date : December 17, 2024

Intervention Details:
  • Drug: Doxycycline
    Participants will be asked to take Doxycycline 100mg/day for 12months duration

Primary Outcome Measures :
  1. Incidence of STI (gonorrhoea, chlamydia and infectious syphilis) per 100 person years among study participants [ Time Frame: 1 year after the last participant complete their last follow-up visit ]
    measured using data collected by the ACCESS study

  2. Patterns of daily doxycycline use and adherence to the medication schedule [ Time Frame: 1 year after the last participant complete their last follow-up visit ]
    measured among participants consenting to the adherence and behavioural online survey

Secondary Outcome Measures :
  1. Evidence of clinically significant antibiotic resistance in in a subset of participants [ Time Frame: 1 year after the last participant who's recruited from the Melbourne site ]
    including those who do contract STIs during the study and those who don't

  2. Behavioural risk practices among study participants [ Time Frame: 1 year after the last participant complete their last follow-up visit ]
    in participants who consent to behavioral data collection online

Biospecimen Retention:   Samples With DNA
oropharynx and rectum swab

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population
Men who report male to male sex in the last 3 months and who have had at least two screening for syphilis, chlamydia and gonorrhoea in the last 12 months, and at least once incidence of syphilis in the last two years, are eligible for the study.

Inclusion Criteria:

  • Male or transgender
  • Aged 18 years or over
  • Reports sex with men in last 3 months
  • At least two screenings for syphilis, gonorrhoea and chlamydia in the past 12 months
  • A diagnosis of syphilis within the last 12 months, OR a diagnosis of any 2 STIs within the last 12 months and syphilis within the last 24 months.
  • HIV +ve, OR HIV -ve and on PrEP for at least 6 months.

Exclusion Criteria:

  • Documented or self-reported hypersensitivity to doxycycline or antimicrobial agents from tetracycline family
  • A known diagnosis of myasthenia gravis
  • Factors or conditions that may compromise a participant's access to health services for follow-up (incarceration or planned relocation that would impact upon proximity to a trial site).

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03709459

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Contact: Yasmin Mowat, BSc +612 9385 1433 ymowat@kirby.unsw.edu.au
Contact: Bridget Haire, PhD +612 9385 1227 b.haire@unsw.edu.au

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Australia, New South Wales
Royal Prince Alfred Hospital Sexual Health Medicine Not yet recruiting
Camperdown, New South Wales, Australia, 2050
Contact: Linda Garton    02 9515 1200    Linda.Garton@health.nsw.gov.au   
Contact: David Templeton    02 9515 1200    David.Templeton@health.nsw.gov.au   
Kirketon Road Centre Recruiting
Sydney, New South Wales, Australia, 2010
Contact: Dr Phillip Read    02 9360 2766    phillip.read1@health.nsw.gov.au   
Principal Investigator: Dr Phillip Read         
Sydney Sexual Health Centre Recruiting
Syd, New South Wales, Australia, 2000
Contact: Dr Anna McNulty    02 9382 7476    anna.mcnulty@health.nsw.gov.au   
Principal Investigator: Dr Anna McNulty         
Australia, Victoria
Melbourne Sexual Health Centre Recruiting
Melbourne, Victoria, Australia, 3053
Contact: Dr Eric Chow    03 9341 6233    EChow@mshc.org.au   
Principal Investigator: Dr Eric Chow         
Sub-Investigator: Professor Christopher K Fairley         
Sponsors and Collaborators
Kirby Institute
South Australian Health and Medical Research Institute
Monash University
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Principal Investigator: Bridget Haire, PhD Kirby Institute, UNSW
Additional Information:

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Responsible Party: Kirby Institute
ClinicalTrials.gov Identifier: NCT03709459    
Other Study ID Numbers: PHIRG1901
First Posted: October 17, 2018    Key Record Dates
Last Update Posted: April 1, 2022
Last Verified: March 2022

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by Kirby Institute:
Syphilis, Gonorrhea, Chlamydia, Doxycycline, PrEP, Syphilaxis
Additional relevant MeSH terms:
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Chlamydia Infections
Chlamydiaceae Infections
Gram-Negative Bacterial Infections
Bacterial Infections
Bacterial Infections and Mycoses
Sexually Transmitted Diseases, Bacterial
Sexually Transmitted Diseases
Communicable Diseases
Genital Diseases
Urogenital Diseases
Neisseriaceae Infections
Treponemal Infections
Spirochaetales Infections
Anti-Bacterial Agents
Anti-Infective Agents
Antiprotozoal Agents
Antiparasitic Agents