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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

The failure of the law

2004-06-04

Written by Lacea Loader

- Call for the protection of consumers’ and tax payers rights against corporate companies

An expert in commercial law has called for reforms to the Companies Act to protect the rights of consumers and investors.

“Consumers and tax payers are lulled into thinking the law protects them when it definitely does not,” said Prof Dines Gihwala this week during his inaugural lecture at the University of the Free State’s (UFS).

Prof Gihwala, vice-chairperson of the UFS Council, was inaugurated as extraordinary professor in commercial law at the UFS’s Faculty of Law.

He said that consumers, tax payers and shareholders think they can look to the law for an effective curb on the enormous power for ill that big business wields.

“Once the public is involved, the activities of big business must be controlled and regulated. It is the responsibility of the law to oversee and supervise such control and regulation,” said Prof Gihwala.

He said that, when undesirable consequences occur despite laws enacted specifically to prevent such results, it must be fair to suggest that the law has failed.

“The actual perpetrators of the undesirable behaviour seldom pay for it in any sense, not even when criminal conduct is involved. If directors of companies are criminally charged and convicted, the penalty is invariably a fine imposed on the company. So, ironically, it is the money of tax payers that is spent on investigating criminal conduct, formulating charges and ultimately prosecuting the culprits involved in corporate malpractice,” said Prof Gihwala.

According to Prof Gihwala the law continuously fails to hold companies meaningfully accountable to good and honest business values.

“Insider trading is a crime and, although legislation was introduced in 1998 to curb it, not a single successful criminal prosecution has taken place. While the law appears to be offering the public protection against unacceptable business behaviour, it does no such thing – the law cannot act as a deterrent if it is inadequate or not being enforced,” he said.

The government believed it was important to facilitate access to the country’s economic resources by those who had been denied it in the past. The Broad Based Economic Empowerment Act of 2003 (BBEE), is legislation to do just that. “We should be asking ourselves whether it is really possible for an individual, handicapped by the inequities of the past, to compete in the real business world even though the BBEE Act is now part of the law?,” said Prof Gihwala.

Prof Gihwala said that judges prefer to follow precedent instead of taking bold initiative. “Following precedent is safe at a personal level. To do so will elicit no outcry of disapproval and one’s professional reputation is protected. The law needs to evolve and it is the responsibility of the judiciary to see that it happens in an orderly fashion. Courts often take the easy way out, and when the opportunity to be bold and creative presents itself, it is ignored,” he said.

“Perhaps we are expecting too much from the courts. If changes are to be made to the level of protection to the investing public by the law, Parliament must play its proper role. It is desirable for Parliament to be proactive. Those tasked with the responsibility of rewriting our Companies Act should be bold and imaginative. They should remove once and for all those parts of our common law which frustrate the ideals of our Constitution, and in particular those which conflict with the principles of the BBEE Act,” said Prof Gihwala.

According to Prof Gihwala, the following reforms are necessary:

• establishing a unit that is part of the office of the Registrar of Companies to bolster a whole inspectorate in regard to companies’ affairs;
• companies who are liable to pay a fine or fines, should have the right to take action to recover that fine from those responsible for the conduct;
• and serious transgression of the law should allow for imprisonment only – there should be no room for the payment of fines.

Prof Gihwala ended the lecture by saying: “If the opportunity to re-work the Companies Act is not grabbed with both hands, we will witness yet another failure in the law. Even more people will come to believe that the law is stupid and that it has made fools of them. And that would be the worst possible news in our developing democracy, where we are struggling to ensure that the Rule of Law prevails and that every one of us has respect for the law”.

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