Darrell Hoi San Tan

OHTNCo-infections, OHTN, Other Comorbidities, people, Prevention, Research Pages

Darrell Tan

OHTN CIHR New Investigator

Darrell Tan is an infectious disease specialist whose research focuses on promoting the sexual health of men who have sex with men. His work aims to improve the prevention, detection and management of HIV and other sexually transmitted co-infections such as herpes and syphilis. He is working to identify and implement effective programs for making pre and post-exposure prophylaxis (PrEP and PEP) accessible to at risk individuals within communities of men who have sex with men and African Caribbean Black communities.

Why OHTN is supporting the development of this investigator:

New biomedical tools are emerging that have potential to prevent HIV transmission in Ontario. The efforts of clinical investigators like Darrell Tan, who work closely with at-risk communities, are vital to improving the prevention and treatment of HIV.

Darrell Tan’s Current Projects

  • Implementing PrEP and PEP – Over the past several years, Darrell Tan has studied strategies for delivering HIV prevention medications to people exposed to HIV outside the health care environment (primarily through sexual risks), working with a network of other health care providers through the University of Toronto Clinical Prevention Unit. PEP (post-exposure prophylaxis) is medication that can be taken after someone has potentially been exposed to HIV, while PrEP (pre-exposure prophylaxis) is a medication taken daily to prevent HIV infection. Darrell Tan is principal investigator of the PREPARATORY-5 study evaluating the delivery of PrEP to men who have sex with men at St Michael’s Hospital. He is also leading the development of clinical guidelines for PEP and PrEP to help physicians across Canada prescribe these medications. He is also planning the development of a national cohort study of PrEP/PEP users to facilitate scale-up of prevention programs across Canada and ongoing monitoring of outcomes. Funding for these efforts have come from OHTN, CIHR, and the University of Toronto.
  • Decentralizing pre-exposure prophylaxis (PrEP) delivery – To make PrEP more accessible, it is necessary to offer this intervention outside of HIV speciality clinics. Darrell Tan and his colleagues are implementing a pilot study engaging nurses in sexual health clinics in delivering PrEP. He is also launching a new initiative to test the feasibility of having patients link their family doctors with online, evidence-based education resources on PrEP hopefully facilitating prescribing through primary care. Funding for this research comes from the Ontario Ministry of Health and Long Term Care and CIHR.
  • Acceptability and Feasibility of New HIV Prevention Technologies for African, Caribbean and Black Populations – This CIHR catalyst grant allows the Tan research team to work with individuals and organizations from African, Caribbean and Black communities to understand their expectations and concerns about PrEP and other new approaches to prevention.
  • Enhanced syphilis screening among HIV-positive men who have sex with men – This CIHR-funded study looks at the potential benefits of including routine syphilis testing with standard HIV blood tests done as part of HIV care to determine if this leads to more timely syphilis diagnosis and treatment.
  • BATARI (Bone Antiresorptive Therapy with AntiRetroviral Initiation) – Initial treatment with some antiretroviral drugs can cause temporary but dramatic decreases in bone mineral density (a measure of bone strength). This CIHR CTN trial explores using osteoporosis treatments during this initial stage to protect bone health. Learn more in this video.

Work Environment and Collaborations

Darrell Tan is a clinician scientist at St. Michael’s Hospital, a scientist at the Li Ka Shing Knowledge Institute and an Assistant Professor at the Institute of Health Policy, Management and Evaluation at the University of Toronto. He is the Director of the University of Toronto HIV Clinical Prevention Unit where he works in conjunction with OHTN Research Chair Rupert Kaul. He is also an investigator with the CIHR Canadian HIV Trials Network. Darrell is a member of the Committee for Accessible AIDS Treatment (CAAT) and part of the Research Advisory Board for Casey House. He combines an active clinical practice with these research activities.

OHTN Support:

Darrell Tan holds an OHTN CIHR New Investigator Award ($300,000; 2013-2018). He and Rupert Kaul receive ongoing support for the University of Toronto HIV Clinical Prevention Unit and its investigations of new prevention technologies ($144,000; 2014-16). He has also received project funding for a study of the logistics of delivering PrEP to men who have sex with men in Toronto ($40,000; 2012-15) and for a study determining the need for lumbar punctures in HIV-positive people diagnosed with syphilis ($139,540; 2011-2015). First funded by OHTN as a co-principal investigator in 2008.