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UFS PhD study focuses on improving life expectancy of HIV/Aids patients

11 December 2019 | Story Leonie Bolleurs

According to Global Statistics, there were approximately 37,9 million people across the globe with HIV/Aids in 2018. They also state that in 2018, an estimated 1,7 million individuals worldwide became newly infected with HIV.

In the city of Masvingo, Zimbabwe, Claris Shoko is a Statistics lecturer at the Great Zimbabwe University. In her PhD thesis at the University of the Free State (UFS) in the Department of Mathematical Statistics and Actuarial Sciences, she presented the argument that the inclusion of both the CD4 cell count and the viral-load counts in the monitoring and management of HIV+ patients on antiretroviral therapy (ART), is helping in reducing mortality rates, leading to improved life expectancy for HIV/Aids patients.

She received her doctoral degree at the December UFS Graduation Ceremonies, with her thesis: Continuous-time Markov modelling of the effects of treatment regimens on HIV/Aids immunology and virology.

CD4 cell count and viral-load count

Dr Shoko explains: “When the human immunodeficiency virus (HIV) enters the human body, the virus attacks the CD4 cells in their blood. This process damages CD4 cells, causing the number of white blood cells in the body to drop, making it difficult to fight infections.”

“Clinical markers such as CD4 cell count and viral-load count (number of HIV particles in a ml of blood) provide information about the progression of HIV/Aids in infected individuals. These markers fully define the immunology and the virology of HIV-infected individuals, thereby giving us a clear picture of how HIV/Aids evolve within an individual.”

Dr Shoko continues: “The development of highly active antiretroviral therapy (HAART) has helped substantially to reduce the death rate from HIV. HAART reduces viral load-count levels, blocking replication of HIV particles in the blood, resulting in an increase of CD4 cell counts and the life expectancy of individuals infected with HIV. This has made CD4 cell counts and viral-load counts the fundamental laboratory markers that are regularly used for patient management, in addition to predicting HIV/Aids disease progression or treatment outcomes.”

In the treatment of HIV/Aids, medical practitioners prescribe combination therapy to attack the virus at different stages of its life cycle, and medication to treat the opportunistic infections that may occur. “The introduction of combined antiretroviral therapy (cART) has led to the dramatic reduction in morbidity and mortality at both individual level and population level,” states Dr Shoko.

Once HIV-positive patients are put on cART, the effectiveness of treatment is monitored after the first three months and a further follow-up is done every six months thereafter. During the monitoring stages, CD4 cell count and viral load is measured. Patients are also screened for any tuberculosis (TB) co-infection and checked for any signs of drug resistance. These variables determine whether or not there is a need for treatment change.

She continues: “Previous studies on HIV modelling could not include both CD4 cell count and viral load in one model, because of the collinearity between the two variables. In this study, the principal component approach for the treatment of collinearity between variables is used. Both variables were then included in one model, resulting in a better prediction of mortality than when only one of the variables is used.”

“Viral-load monitoring helps in checking for any possibilities of virologic failure or viral rebound, which increases the rate of mortality if not managed properly. CD4 cell count then comes in to monitor the potential development of opportunistic infections such as TB. TB is extremely fatal, but once detected and treated, the survival of HIV/Aids patients is assured,” Dr Shoko explains.

Markov model

She applied the Markov model in her study. The model, named after the Russian mathematician Andrey Markov, represents a general category of stochastic processes, characterised by six basic attributes: states, stages, actions, rewards, transitions, and constraints.

According to Dr Shoko, Markov models assume that a patient is always in one of a finite number of discrete states, called Markov states. All events are modelled as transitions from one state to another. Each state is assigned a utility, and the contribution of this utility to the overall prognosis depends on the length of time spent in each state. For example, for a patient who is HIV positive, these states could be HIV+ (CD4 cell count above 200 cells/mm3), Aids (CD4 cell count below 200 cells/mm3) and Dead.

“Markov models are ideal for use in HIV/Aids studies, because they estimate the rate of transition between multiple-disease states while allowing for the possible reversibility of some states,” says Dr Shoko, quoting Hubbard and Zhou.

“Relatively fewer HIV modelling studies include a detailed description of the dynamics of HIV viral load count during stages of HIV disease progression. This could be due to the unavailability of data on viral load, particularly from low- and middle-income countries that have historically relied on monitoring CD4 cell counts for patients on ART because of higher costs of viral load-count testing,” Dr Shoko concludes

News Archive

“To forgive is not an obligation. It’s a choice.” – Prof Minow during Reconciliation Lecture

2014-03-05

“To forgive is not an obligation. It’s a choice.” – Prof Minow during the Third Annual Reconciliation Lecture entitled Forgiveness, Law and Justice.
Photo: Johan Roux

No one could have anticipated the atmosphere in which Prof Martha Minow would visit the Bloemfontein Campus. And no one could have predicted how apt the timing of her message would be. As this formidable Dean of Harvard University’s Law School stepped behind the podium, a latent tension edged through the crowded audience.

“The issue of getting along after conflict is urgent.”

With these few words, Prof Minow exposed the essence of not only her lecture, but also the central concern of the entire university community.

As an expert on issues surrounding racial justice, Prof Minow has worked across the globe in post-conflict societies. How can we prevent atrocities from happening? she asked. Her answer was an honest, “I don’t know.” What she is certain of, on the other hand, is that the usual practice of either silence or retribution does not work. “I think that silence produces rage – understandably – and retribution produces the cycle of violence. Rather than ignoring what happens, rather than retribution, it would be good to reach for something more.” This is where reconciliation comes in.

Prof Minow put forward the idea that forgiveness should accompany reconciliation efforts. She defined forgiveness as a conscious, deliberate decision to forego rightful grounds of resentment towards those who have committed a wrong. “To forgive then, in this definition, is not an obligation. It’s a choice. And it’s held by the one who was harmed,” she explained.

Letting go of resentment cannot be forced – not even by the law. What the law can do, though, is either to encourage or discourage forgiveness. Prof Minow showed how the law can construct adversarial processes that render forgiveness less likely, when indeed its intention was the opposite. “Or, law can give people chances to meet together in spaces where they may apologise and they may forgive,” she continued. This point introduced some surprising revelations about our Truth and Reconciliation Commission (TRC).

Indeed, studies do report ambivalence, disappointment and mixed views about the TRC. Whatever our views are on its success, Prof Minow reported that people across the world wonder how South African did it. “It may not work entirely inside the country; outside the country it’s had a huge effect. It’s a touchstone for transitional justice.”

The TRC “seems to have coincided with, and maybe contributed to, the relatively peaceful political transition to democracy that is, frankly, an absolute miracle.” What came as a surprise to many is this: the fact that the TRC has affected transitional justice efforts in forty jurisdictions, including Rwanda, Sierra Leone, Cambodia and Liberia. It has even inspired the creation of a TRC in Greensborough, North Carolina, in the United States.

There are no blueprints for solving conflict, though. “But the possibility of something other than criminal trials, something other than war, something other than silence – that’s why the TRC, I think, has been such an exemplar to the world,” she commended.

Court decision cannot rebuild a society, though. Only individuals can forgive. Only individuals can start with purposeful, daily decisions to forgive and forge a common future. Forgiveness is rather like kindness, she suggested. It’s a resource without limits. It’s not scarce like water or money. It’s within our reach. But if it’s forced, it’s not forgiveness.

“It is good,” Prof Minow warned, “to be cautious about the use of law to deliberately shape or manipulate the feelings of any individual. But it is no less important to admit that law does affect human beings, not just in its results, but in its process.” And then we must take responsibility for how we use that law.

“A government can judge, but only people can forgive.” As Prof Minow’s words lingered, the air suddenly seemed a bit more buoyant.

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