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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

Conference: Expanded ARV treatment

2005-03-02

VENUE: University of the Free State, Bloemfontein, South Africa
DATE: 30 March 2005 - 1 April 2005

ARV Programme as on 24Feb Download Word document
Programme Special events Download Word document

Official web site www.fshealth.gov.za/subsites/arvc

Rationale for the Conference
At the time of the planned Conference, much ground would have been covered, both in the Free State and in South Africa, in respect of the expanded public sector ARV treatment programme in respect of research, experiences in practice, training of staff, treatment of patients, lessons learned, successes and failures, etc. The time would then be quite opportune to share these in a systematic manner with other provinces and countries, as well as with the large variety of stakeholders and role players in the ARV and related domains, be they academics and researchers, policy makers and service/facility managers, the variety of caregivers, and the community organisations and affected patients.

The Conference and current research
The proposed Conference is, firstly, directly linked to the current research on the public sector roll-out of ARV treatment in the Free State conducted by several research institutions (e.g. CIET, CHSR&D, UCT Lung Institute). Secondly, the Conference could and would serve as a forum for other research groups in the country and further a field to report and share knowledge and experiences on ARV treatment and related initiatives. Lastly, the Conference will stage a golden opportunity for researchers and scientists, on the one hand, and policy makers, managers, and caregivers (as knowledge users), on the other hand, to engage in cross-disciplinary discourse on this mutual and topical theme.

Theme of Conference
Expanded ARV treatment in the Free State: sharing experiences

Focus
The focus is primarily on public sector ARV treatment in the Free State, but also initiatives/activities/perspectives of relevance to the Free State elsewhere in the country at large and further a field, as well as relevant ARV initiatives in the public, private, NGO and FBO sectors. Bear in mind, however, that ARV treatment is but part of a much more comprehensive approach to HIV and AIDS. The Conference will, therefore, not narrowly focus on the ARV treatment programme only. The broader context, other relevant dimensions, and a comprehensive approach to the challenges of HIV, AIDS and TB are of equal importance.

The purpose of the Conference
Enhance meaningful exchange, mutual understanding and collaboration among researchers, scientists, policy makers, managers and practitioners in the field of ARV treatment and related fields.

Share experiences in the various spheres of ARV treatment and related spheres (policy, management, practice, research, training, public-private-civil society sectors).

Record, reflect and report on the establishment of the ARV treatment programme in the Free State, and in within the context of the comprehensive HIV/AIDS programme.

Disseminate important research results on ARV treatment and related themes to health policy makers, managers, practitioners, communities and to the research community.

Stimulate discourse among various disciplines and various stakeholders/role players involved in ARV treatment and related programmes.

Sensitise and acquaint researchers to the requirements of policy makers, managers and practitioners in respect of ARV treatment and related fields.

Facilitate the implementation of research results in ARV treatment policy, programmes and practice.

Dissemination of Conference-related information
Information generated during the Conference could feed into policy, management and practice of ARV treatment, the training accompanying such programme, and the existing body of knowledge. After the Conference the information will be disseminated via the Internet and by scientific and popular publications.

Date and duration
Set for 30 & 31 March & 1 April 2005; to commence at 09:00 on the first day (30 March) and to end at 16:30 (1 April) the third day.

Format and scope of Conference
Alternating plenary, parallel sessions and debates focused on topical issues and interest groups. The Conference will strive to be maximally interactive and participative.

Themes and topics to cover:

Policy, management and health services/practice (various levels and contexts – clinical treatment, information, IT systems, pharmacy, laboratories, nutrition)
Research covering all relevant disciplines and diverse dimensions of ARV treatment and related themes
Training and evaluation of training
Patients, communities and civil society organisations
Public, private, NGO, FBO initiatives and partnerships

Emphasis will be on the Free State, however, with of significant involvement from other provinces, SADC countries, and countries further a field. The thrust will be to export lessons and experiences from the Free State, but also to import lessons and experiences from other provinces, countries and sectors.

Presenters
Key presenters from the Free State, other provinces, South Africa, from the private, FBO and NGO sectors, and from several other countries

Delegates
About half of the delegates will be Free State stakeholders and role players (all levels and all contexts). The other half will be role players and stakeholders in the ARV and related fields from other provinces, the national level, and other countries, as well as from the private, public and non-governmental sectors.

Focused workshops
Provision will be made for half-a-day or one-day workshop initiatives on the third day (1 April 2005).

Enquiries
For more information please contact:

Prof Dingie van Rensburg
Centre for Health Systems Research & Development
University of the Free State
PO Box 339
Bloenfontein
SOUTH AFRICA
9300

Contact:
Carin van Vuuren
Conference Organiser
Centre for Health Systems Research & Development
University of the Free State
P.O.Box 339
Bloemfontein
South Africa
9300
Tel +27 (0) 51 401 2181
Fax +27 (0) 51 4480370
Cell 0832932890
e-mail: arvconference.hum@mail.uovs.ac.za

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