Areas of research

The OHTN Cohort Study research program focuses on four key areas of research

  1. Social and Behavioral Research
  2. Clinical Research
  3. HIV Prevention Research
  4. Health Services Research



Hepatitis C co-infection is associated with an increased risk of incident chronic kidney disease in HIV-infected patients initiating combination antiretroviral therapy. (May 2017)

Summary: Combination antiretroviral therapy (cART) has reduced mortality from AIDS-related illnesses. At the same time, chronic comorbidities have become prevalent among HIV-infected patients. We examined the association between hepatitis C virus (HCV) co-infection and chronic kidney disease (CKD) among patients initiating modern antiretroviral therapy; we found the two were associated.

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Burden and risk factors for gastrointestinal symptom distress in HIV patients in the modern antiretroviral era (February 2017)

Summary: In the modern antiretroviral (ARV) era, there is limited knowledge about the prevalence and risk factors for HIV patient-reported gastrointestinal (GI) symptoms (diarrhoea/soft stool, nausea/vomiting, bloating/painful abdomen, loss of appetite, and weight loss/wasting) and distress. We prospectively analysed data (2007-2014) on distressing GI symptoms from the OCS. With the exception of bloating, odds were significantly lower for those on ARV containing integrase inhibitors and greater for patients reporting current cannabis use. GI symptoms in the modern ARV era are highly prevalent and may arise as a common pathway of distress in response to psychosocial vulnerabilities.

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Trends and Correlates of Cigarette Smoking and Its Impacts on Health-Related Quality of Life Among People Living with HIV: Findings from the Ontario HIV Treatment Network Cohort Study, 2008-2014 (February 2017)

Summary: We sought to examine the trends of cigarette smoking, identify correlates of smoking, and examine the impacts of smoking on health-related quality of life (HRQOL) among people living with HIV. We found that Current cigarette smokers were more likely to be younger, male, white or indigenous, Canadian-born, single, unemployed with lower education, heavy drinkers, nonmedicinal drug users, and to have current depression. Current cigarette smokers also had significantly worse physical and mental health scores than those who never smoked.

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Childhood Adversities and Physical and Mental Health Outcomes in Adults Living with HIV: Findings from the Ontario HIV Treatment Network Cohort Study (March 2018)

Summary: We sought to estimate the prevalence of childhood adversity and examine its relationship with health outcomes among people living with HIV. The prevalence of childhood adversity was 71%; higher prevalence was associated with younger age, Indigenous or African/Caribbean/Black ethnicity, lower socioeconomic status, and higher rates of cigarette smoking and nonmedicinal drug use. Greater number of childhood adversities was associated with greater odds of depression and decreased mental health related quality of life.

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Impact of depression and recreational drug use on emergency department encounters and hospital admissions among people living with HIV in Ontario: A secondary analysis using the OHTN cohort study (April 2018)

Summary: Nearly half of HIV-positive patients experience mental health and substance use problems, but many do not receive adequate or ongoing mental health or addiction care. This lack of ongoing care can result in the use of costly acute care services. We found a significant increase in emergency department services use and potentially avoidable ED encounters, particularly among those with either current depression or recreational drug use.

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The impact of drug coverage on viral suppression among people living with HIV in Ontario, Canada (December 2018)

Summary: We investigated the effect of drug coverage on viral suppression (sVL) in Ontario, Canada, where there is no universal coverage of prescription drugs, including antiretroviral therapy (ART). Our findings suggest that drug coverage can affect viral suppression in our setting.

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Lost but not forgotten: A population-based study of mortality and care trajectories among people living with HIV who are lost to follow-up in Ontario, Canada (November 2018)

Summary: Do estimates of mortality and other health outcomes that are based on cohort participants suffer from an inherent selection bias? We estimated mortality and health service use among people living with HIV (PLWH) who were lost to cohort follow-up from a volunteer clinical HIV-infected cohort, and compared these to mortality and health service use in active cohort participants and non-cohort-participants living with HIV. We found that mortality risk and use of health care resources were lower among active cohort participants.

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Late diagnosis, delayed presentation and late presentation among persons enrolled in a clinical HIV cohort in Ontario, Canada (1999–2013) (November 2018)

Summary: Timely HIV diagnosis and presentation to medical care are important for treatment and prevention. Our objective was to measure late diagnosis, delayed presentation and late presentation. We found that late diagnosis (53.0%) and presentation (54.0%) were common. Characteristics associated with higher odds of late diagnosis/presentation in multivariable analyses included older age at diagnosis/presentation; African, Caribbean and Black race/ethnicity; Indigenous race/ethnicity; female sex; and being a male who did not report sex with men.

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The Effect of MSM and CD4+ Count on the Development of Cancer AIDS (AIDS-defining Cancer) and Non-cancer AIDS in the HAART Era (2018)

Summary: The HIV epidemic is increasing among Men who have Sex with Men (MSM) and the risk for AIDS defining cancer (ADC) is higher among them. We set out to examine the effect of being MSM, and CD4+ count, the development of cancer AIDS (ADC) and noncancer AIDS in competing risk setting in the HAART era, and found that MSM face a greater hazard of cancer AIDS.

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A longitudinal investigation of the association between cannabis use and alcohol use among people living with HIV (December 2018)

Summary: Both cannabis use and alcohol use are elevated among people living with HIV, but few studies have investigated the relationship between cannabis use and alcohol use in this population. Our participants completed assessments of cannabis use, reasons for cannabis use, and alcohol use at baseline and at annual follow-ups. We found that cannabis use and alcohol use were positively associated over time, although this association was specific to those using cannabis for recreational reasons.

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Stigma, Coping, and Alcohol Use Severity Among People Living With HIV: A Prospective Analysis of Bidirectional and Mediated Associations (August 2018)

Summary: HIV-related stigma is associated with health consequences among people living with HIV, including increased risk for alcohol problems; theory suggests that alcohol use may serve as a maladaptive coping strategy. We observed that HIV-related stigma consistently predicted increased maladaptive coping 1 year later. Similarly, maladaptive coping consistently predicted greater subsequent HIV-related stigma.

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Brief Report: Syphilis Coinfection Is Not Associated With an Increased Risk of Virologic Failure Among HIV-Positive Men Who Have Sex With Men on Antiretroviral Therapy (April 2019)

Summary: Incidence of syphilis continues to increase among HIV-positive men who have sex with men (MSM) in Ontario. Our results indicate that acute syphilis was not associated with VF among virologically suppressed MSM on ART. Consequently, ART may still reduce HIV transmission risk to sexual partners.

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Contact the Study Coordinator Eliot Winkler at [email protected] if interested in a publication that is not available as a full text online.


Accessing data

How can I access OHTN Cohort Study data? The OHTN Cohort Study encourages new and past collaborators to submit proposals for analysis projects. The following 5 steps are required to complete the Research Application Process (RAP). A more detailed description of the Research Approval Process is set out in the Terms of Reference.

Step 1: Research idea
We know that developing a research idea can be challenging especially when one is not familiar with the scope and limitations of the OHTN Cohort Study. In an effort to support collaborators to develop focused research questions we ask that they submit an OHTN Cohort Study Concept Sheet to the OHTN Cohort Study research coordinator. Following review and approval of an OHTN Cohort Study Concept Sheet, collaborator(s) may submit a “Data Scan Request” form to obtain aggregate-level OHTN Cohort Study data to assess study feasibility.

Step 2: Developing an OCS Project Proposal
Collaborators will be encouraged to complete an OCS Project Proposal only after the review and approval of an OCS Concept Sheet. All Research Project Proposals must contain the information set out in the OCS Research Proposal Checklist, in particular, whether OHTN Cohort Study data are sought in Standard Release or Conditional Release format. It’s important to note that the Research Project Proposal must be eligible for implicit approval by the research ethics board (REB) of the University of Toronto or have obtained research ethics board (REB) review and approval from the University of Toronto.

Step 3: OHTN Cohort Study: Scientific Review of Research Project Proposals
The OHTN Cohort Study Scientific Steering Committee conducts scientific review to ensure that the research objectives and the analytical plan of each proposal are scientifically feasible and methodologically sound. The Scientific Steering Committee will also assess the necessity of each data element requested in the Research Project proposal to assess whether the proposal presents a risk of residual disclosure and, if so, to recommend how any such risk may be addressed. A Research Project Proposal that has obtained research ethics board (REB) approval from the University of Toronto may be exempted from OHTN’s scientific review by the OHTN Cohort Study Principal Investigator. Following scientific review, the Scientific Steering Committee may recommend the Research Project Proposal for approval as proposed or with revision(s). A proposal will proceed for review by the Governance Committee if and as approved by the Scientific Steering Committee.

Step 4: Community Review by OHTN Cohort Study Governance Committee
The purpose of community review by the Governance Committee is to review each Research Project Proposal following successful scientific review for ethical considerations and for consistency with the OHTN and OHTN Cohort Study’ guiding principles. The Governance Committee may, approve the Research Project Proposal as proposed or with comments and/or revision(s). Once approved, a Research Project Proposal is a “Research Project”.

Step 5: Release of OHTN Cohort Study Data
The OHTN will disclose to Research Project PIs (or their Research Project Team members) only that OHTN Cohort Study Data which has been approved for collection, use and/or disclosure in accordance with steps 3 and 4 above. The OHTN will disclose approved OHTN Cohort Study Data in a release format that provides OHTN Cohort Study participants with the greatest possible protection of their privacy and confidentiality while still meeting the administrative and/or research purposes for which the collection, use and/or disclosure of OHTN Cohort Study data have been authorized.


Scientific steering committee

  • Sergio Rueda, Chair
  • Barry Adam
  • Adrian Betts
  • Ann Burchell
  • Tracey Conway
  • Curtis Cooper
  • Trevor Hart
  • Lucia Light
  • Mona Loutfy
  • Kelly O’Brien
  • David Brennan
  • Abigail Kroch
  • Lawrence Mbuagbaw
  • Pierre Giguere
  • Winston Husbands
  • Anita Benoit


OHTN Cohort Study Questionnaire

The OHTN Cohort Study questionnaire was introduced in 2007 to augment the scope of data collected through clinical chart extraction. Participants are requested to complete an interviewer administered questionnaire yearly. The questionnaire is modular allowing the OHTN Cohort Study the flexibility to ask different questions every year. The base interview module takes approximately 30 minutes to complete. Each year there may be additional sections which are added up to a time maximum of 120 minutes. Participant responses are collected electronically using an online, electronic form linked to the encrypted unique identifier (Pseudo-ID) and reversibly encrypted/scrambled prior to secure data transfer.

The sections of the questionnaire generally include

  • Demographics
  • Immigration, Race and Ethnicity
  • Employment Status and Occupation
  • Income and Education
  • Housing Status
  • Alcohol Use
  • Cigarette Smoking History
  • Cannabis Use
  • Non-Medicinal Drug Use
  • HIV Risk Factors
  • Symptom Distress
  • Body Change and Distress
  • Health Related Quality of Life
  • Adherence; Mental Health
  • Social Support
  • Stigma
  • Stress
  • Mastery
  • Coping
  • Additional Health Practices
  • Health Utilities Index
  • Prevention
  • HIV and the Law

Where possible validated instruments are chosen:

  • Alcohol use (AUDIT)
  • Symptom distress (ACTG)
  • Body change and distress (ACTG)
  • Health related quality of life (SF-36 or SF-12, and the EQ5D)
  • Adherence (ACTG)
  • Mental health (K10 or CES-D or Patient Health Questionnaire (PHQ-9)
  • Mini International Neuropsychiatric Instrument (MINI)
  • Social support (MOS-SSS or ACTG)
  • Stigma (HIV Stigma Scale)
  • Stress (Recent Life Events)
  • Chronic Stress Measure
  • Early Childhood Activities
  • Mastery (Pearlin Mastery Scale)
  • Coping (Brief COPE) and the Health Utilities Index