Research has found that taking HIV treatment (ART) every day exactly as prescribed and directed—adherence—generally results in improved measures of health. This occurs because within several months after initiating ART the amount of HIV in the blood usually falls to a very low level—so low that it cannot be accurately measured with routine lab tests. This low level is commonly called “undetectable.” Clinical trials have shown that HIV-positive people who achieve and maintain an undetectable viral load do not transmit the virus to their sexual partners.
Focus on adherence
Adherence is important when trying to achieve benefits that accompany the treatment of nearly all conditions. In HIV disease, studies have found that very high levels of adherence (95% or greater) are needed to maintain the health and prevention benefits that come with ART. As excellent adherence is essential for the success of HIV treatment and prevention, teams of researchers continue to study it.
In British Columbia
Researchers at the B.C. Centre for Excellence in HIV/AIDS and elsewhere in Vancouver have been collecting information related to treatment adherence from HIV-positive people over a period of 15 years. Their analysis of this data has found that the proportion of people with optimal adherence to ART was significantly less in women (57%) compared to men (77%).
Readers should note that the B.C. study was not designed to uncover the reasons for these differences in adherence. But it is a good first step toward designing a study and writing and submitting a funding proposal to funding agencies. Hopefully such a proposal will get funded so that research can be done with HIV-positive women in B.C. to better understand the drivers of poor adherence. The results of such a study could then be used to develop ways to enhance existing services for HIV-positive women and to support their adherence.
Estimating adherence
Assessing adherence directly is time consuming and expensive. Therefore, researchers with the B.C. team assessed adherence indirectly by accessing pharmacy records to determine if prescriptions were refilled in a timely manner. This indirect method of assessing adherence has been validated in previous studies with HIV-positive people.
The B.C. team assessed adherence at intervals of six months. Here is an example provided by the researchers:
“In a six-month period, or 183 days, an individual may be seven days late to fill their prescription. In this case, adherence would be calculated by dividing 176 days (the period for which the individual has medications) by 183 days, resulting in 96% adherence for the period.”
Using pharmacy refill information may seem like an oversimplified way to estimate adherence, as collecting a refill of a prescription could be different from a person’s pill-taking habits. However, as mentioned previously, using pharmacy refills as a way of estimating adherence has been validated in other studies and has been linked to a person’s viral load. That is, people who had suboptimal adherence based on pharmacy refill data were more likely to have a detectable viral load.
In an era when funding for HIV research is not increasing significantly, it is likely that more scientists will make use of pharmacy refill data to estimate overall adherence in whatever population is being studied.
For their analysis, researchers collected data from 4,534 HIV-positive people between January 1, 2000 and December 31, 2014. On average participants were monitored for about five and a half years.
Results
Using a definition where optimal adherence was 95% or greater, the researchers found that, overall, the distribution of optimal adherence was as follows:
- women – 57%
- men – 77%
This difference was statistically significant; that is, not likely due to chance alone.
The findings from the B.C. study are broadly similar to what has been reported by other researchers who have reviewed adherence to ART in other high-income countries.
Possible reasons
Although the present B.C. study was not designed to uncover reasons for poor adherence, the B.C. researchers suggested that women in their study might have been vulnerable to factors that impacted adherence. According to the researchers, such factors would have arisen from circumstances that intersected with their race/ethnicity, a history of abuse, and injection drug use. We now explore some of these issues.
Indigenous ancestry
The B.C. researchers observed that, overall, Indigenous people were less likely to be highly adherent to their treatment than non-Indigenous people. In explaining this link, they advanced the following points relevant to the Canadian context:
- Indigenous people have been disproportionally affected by HIV
- Indigenous people have received “lower quality HIV-related care”
- Indigenous people have had poorer health-related outcomes
A lasting legacy
The researchers noted: “Poorer health outcomes among Indigenous people, such as HIV-related [illness and death], cannot be discussed without connecting these conditions with Canada’s history of colonialization, marginalization and criminalization of culture. The negative impact of Canada’s colonial legacy can still be observed in the disproportional rates of injection drug use, alcoholism and suicide, in addition to the [continued spread of HIV among Indigenous people]…. In the context of colonialism, there is a need for culturally competent HIV-related care to support ART adherence and to build trust between Indigenous people and non-Indigenous HIV-care providers.”
Injecting street drugs
The B.C. researchers took into account injection drug use to see whether or not this had an impact on adherence. However, for 55% of participants there was no information about injecting street drugs. This lack of information may have inadvertently biased the researchers’ conclusions. However, among participants for whom this data was available, gender (in this case being a woman) continued to be the main factor associated with poor adherence.
Issues among women
It is possible that there were issues that affected women that could have had an impact on their ability to adhere to ART. For instance, the researchers put forward the following possibilities:
- women may have experienced more medication-related side effects than men
- women may have had reduced levels of social support than men, which could have caused them to feel isolated and stressed and affected their ability to cope with HIV
- many women have competing demands placed on them, such as the caring for children and/or their partner, “in addition to the basic needs of housing and food security.”
The researchers said that women with a history of abuse and in the absence of women-centred care may be especially vulnerable to these competing demands on their time, energy and ability to look after themselves.
Getting to 90-90-90
The power of ART to help reduce the spread of HIV is so tremendous that the United Nations Joint Programme on HIV/AIDS (UNAIDS) has set goals to which cities, regions and countries can aspire by the year 2020. These goals are encompassed in the shorthand phrase 90-90-90:
- 90% of all people living with HIV will know their HIV status
- 90% of all people with diagnosed HIV infection will receive sustained antiretroviral therapy
- 90% of all people receiving antiretroviral therapy will have viral suppression (that is, they will achieve and maintain an undetectable viral load)
If Canada is to meet these targets, it will have to intensify efforts working with Indigenous and other populations affected by HIV.
The B.C. study provides the rationale for researchers to develop a proposal for which they then need to secure funding so that they can understand why some people with HIV in that province need help with adherence to ART.
—Sean R. Hosein
REFERENCES:
- Puskas CM, Kaida A, Miller CL, et al. The gender gap: a longitudinal examination of men’s and women’s ART adherence in British Columbia, 2000-2014. AIDS. 2017; in press.
- Cohen MS, Chen YQ, McCauley M, et al. Antiretroviral therapy for the prevention of HIV-1 transmission. New England Journal of Medicine. 2016;375:830–9. Available from: http://www.nejm.org/doi/pdf/10.1056/NEJMoa1600693
- Rodger AJ, Cambiano V, Bruun T, et al. Sexual activity without condoms and risk of HIV transmission in serodifferent couples when the HIV-positive partner is using suppressive antiretroviral therapy. Journal of the American Medical Association. 2016;316(2):171–81. Available from: http://jama.jamanetwork.com/article.aspx?articleid=2533066
- Grossberg R, Zhang Y, Gross R. A time-to-prescription-refill measure of antiretroviral adherence predicted changes in viral load in HIV. Journal of Clinical Epidemiology. 2004 Oct;57(10):1107-10.
- Bisson GP, Gross R, Bellamy S, et al. Pharmacy refill adherence compared with CD4 count changes for monitoring HIV-infected adults on antiretroviral therapy. PLoS Medicine. 2008 May 20;5(5):e109.
- Bolsewicz K, Debattista J, Vallely A, et al. Factors associated with antiretroviral treatment uptake and adherence: A review. Perspectives from Australia, Canada, and the United Kingdom. AIDS Care. 2015;27(12):1429-38.
- de Boer IM, Prins JM, Sprangers MA, et al. Using different calculations of pharmacy refill adherence to predict virological failure among HIV-infected patients. Journal of Acquired Immune Deficiency Syndromes. 2010 Dec 15;55(5):635-40.