Investigating intervention strategies for the management of diabetes in South Africa: A system dynamics approach

The increasing prevalence of diabetes mellitus in the world is a widespread concern. According to predictions by the International Diabetes Federation, the prevalence of diabetes is expected to increase globally from 415 million in 2015 to 642 million by 2040. While improvement has been made in the epidemiology and management of diabetes in the developed world, the same advances have not been made in South Africa. Similarly to the rest of the world, South Africa is experiencing an increasing prevalence of diabetes, in addition to the highest global prevalence of HIV and Tuberculosis. With more chronically-ill patients, public primary health care facilities are under significant strain to dedicate sufficient resources to assist all patients. This, in turn, minimises the available time allocated to other aspects of primary health care, which includes intervention strategies such as screening and prevention through education. In addition, while the private and public sector both receive a similar share of the GDP for health care, the private health care sector only services a fraction of the population. This inequality between the private and public health sectors proves to be significant challenge that hinders the effective management of diabetes in the public health care system. Furthermore, the prevention and treatment of diabetes is a complex process which requires consistent and methodological care to prevent the onset or progress of the disease. Despite national diabetic policy implementation in 2014, the prevalence of type 2 diabetes has, however, steadily increased from the 4.5% in 2010 to 7% in 2017. In addition, the proportion of all diabetic-related deaths in South Africa has increased from 5.1% in 2014 to 5.5% in 2017. This increase in the prevalence of type 2 diabetes, along with the increased diabetes-related mortality, raises questions relating to the effectiveness of existing diabetes interventions in South African diabetic policy. The primary research aim of this thesis is, therefore, to investigate existing intervention strategies for policy formulation so as to more effectively manage diabetes within South Africa. Due to the complex nature and non-linear interactions that exist within the diabetic health care system in South Africa, and through the analysis of various modelling approaches, system dynamics modelling was selected as an appropriate analysis method to evaluate diabetic policy interventions and gain insight the causal relationship within this system. Twelve dynamic hypotheses are proposed in the form of a causal loop diagram which is used in the development of a system dynamics model. Using the system dynamics methodology, the dynamics of the (i) non diabetic, (ii) undiagnosed and diagnosed prediabetic, (iii) undiagnosed and diagnosed diabetic, and (iv) undiagnosed and diagnosed diabetic with complications populations are modelled using the Vensim DSS software. Policy intervention scenarios are then developed so as to determine the effect of various policy interventions on the total diabetic death rate per year. These scenarios included changing the resource allocation of (i) the health care professional to patient ratio, (ii) self-management education, (iii) lifestyle education, (iv) screening interventions and (v) the availability of medical resources. Using the scenario results, policy considerations are presented so as to provide insight into the complex and dynamic diabetic health care system, as well as to highlight effective causal relaiii Stellenbosch University https://scholar.sun.ac.za