Some HIV-positive women in Canada have poorer responses to therapy

Potent combination therapy for HIV (commonly called ART or HAART) can improve and maintain the health of people who use it. In Canada and similar countries researchers have found that the benefits of ART are so tremendous that rates of AIDS-related infections and deaths associated with AIDS have significantly declined since 1996. Furthermore, researchers predict that a young adult who is infected today and is diagnosed and initiates treatment shortly thereafter and who is engaged in their care and treatment and does not have co-morbidities (such as untreated or poorly managed depression, schizophrenia, addiction or co-infections) is likely to survive for several decades.

Focus on women

Although there have been massive reductions in AIDS-related illnesses and deaths, other troubling trends exist. For instance, in the past decade thousands of new HIV infections have occurred in Canada and women now make up nearly 25% of the population with this infection. As a comparison, in the first two decades of the HIV epidemic in Canada, women comprised 12% of cases.

In three provinces—A summary

Researchers in three provinces—British Columbia, Ontario and Quebec—recently analysed health-related information collected from 5,442 HIV-positive people since the year 2000. The researchers found that women generally began ART at an earlier age than men and that women were more likely than men to disclose that they injected street drugs. However, regardless of their history of injecting drugs, women in this study were less likely than men to achieve an HIV viral load less than 50 copies/ml. Furthermore, even if they did manage to get their viral load below the 50-copy threshold, women were more likely to have this degree of virologic control as a temporary event, as their viral loads would eventually rise above the 1,000 copies/ml level.

Reducing the amount of HIV in the blood (viral load) to the lowest possible level and keeping it there is a key goal of ART. This decrease in the production of HIV allows the immune system to partially repair itself and usually results in improved overall health.

Study details

Researchers analysed health-related information collected from 5,442 HIV-positive people distributed as follows:

  • men – 4,322
  • women – 1,120

Participants entered the database when they began to take ART. This particular database, called CANOC, collects health-related information from major HIV clinics in BC, Ontario and Quebec.

Researchers working with the CANOC  database sought differences in responses to ART between men and women.


In general, prior to starting ART women tended to be younger (36 years) than men (41 years) and had lower viral loads (40,000 copies/ml in women vs. 79,000 copies in men). Also, more women (44%) than men (29%) disclosed a history of injecting street drugs. Women were more likely to be co-infected with hepatitis C virus (HCV) than men.

Regardless of drug use

Whether or not women in the study had a history of injecting street drugs, they were more likely than men to have poorer responses to ART. That is, their viral loads were less likely to fall below the limit of detection (50 copies/ml).

Furthermore, women who were able to suppress their viral load below the 50-copy/ml mark were more likely to eventually have it rise above 1,000 copies/ml compared to men.

Despite all this, researchers could not detect any significant differences in survival between men and women.

Reasons for differences

The CANOC researchers based their study on medical records stored in a database. Such records are relatively incomplete and so they are unable to give a precise reason for the differences that were found. Nevertheless, there are several possible reasons that could explain the study’s findings, such as the following:

1. There are relatively high rates of women with a history of injecting street drugs in this study. This is probably due to the recruitment of many women from BC, where generally there are higher rates of drug use among HIV-positive patients than in other provinces.

2. The CANOC study has limitations—data were collected and analysed from three provinces. Moreover, the data from BC consisted of all HIV-positive people who were taking treatment in that province. In contrast, data from the other provinces were from selected clinics.

3. Information on participants’ ability to take ART every day exactly as directed was not available.

4. Some medical records might have been incomplete, specifically about whether or not patients had a history of injecting street drugs.

5. Not all deaths that occurred among participants were captured in medical records.

The big picture

Despite these potential shortcomings, it is clear that some HIV-positive women in care do not achieve the best possible outcome when using ART. There are likely many factors that affect the health of HIV-positive women who were in this study, including factors such as domestic violence, prioritizing the care of other family members, social isolation and its consequences (anxiety and depression). Whatever the underlying reasons for the differences between genders found in this analysis, the findings have uncovered a troubling issue. Other studies are needed at the local clinic level in at least the three provinces that contributed to this study to assess the reasons for the poorer virological response among women. Such studies could be used as a starting point for improving the health of HIV-positive women in Canada.

—Sean R. Hosein


Cescon A, Patterson S, Chan K, et al. Gender differences in clinical outcomes among HIV-positive individuals on antiretroviral therapy in Canada: a multisite cohort study. PLoS One. 2013 Dec 31;8(12):e83649.