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

Thomas, Victoria (2019-12)

Thesis (MEng)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: 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 e ect 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 relationships. It is shown that through the implementation of two interventions, powerful causal relationships can be established between the health care professional to patient ratio and selfmanagement education interventions, as well as between the health care professional to patient ratio and availability of medical resources interventions. The most significant causal relationship is, however, observed between these three aforementioned interventions | the health care professional to patient ratio, self-management education and availability of medical resources interventions. Although the lifestyle education intervention is shown to reduce the total diabetic deaths per year, no strong relationship was identified in combination with other interventions. The lifestyle education intervention, however, proves to be an effective supportive intervention to already powerful intervention combinations. Finally, although the screening intervention was proven to be the most effective intervention in reducing the undiagnosed diabetic deaths per year, the impact of the screening intervention on the undiagnosed diabetic deaths per year is shown to be significantly less than the impact of the other interventions on the diagnosed diabetic deaths per year.

AFRIKAANSE OPSOMMING: Die wêreldwye toename in die voorkoms van diabetes mellitus is 'n bron van kommer. In 2015 was 415 miljoen mense wêreldwyd met die siekte gediagnoseer, die Internasionale Diabetes Federasie voorspel dat di getal teen 2040 na 642 miljoen sal toeneem. Alhoewel verbeteringe in die epidemiologie en bestuur van diabetes reeds in ontwikkelde lande gemaak is, is dieselfde vooruitgang nog nie in Suid-Afrika gemaak nie. Ooreenkomstig met die res van die wêreld, wervaar Suid-Afrika 'n toenemende voorkoms van diabetes, tesame met die hoogste voorkoms van MIV en tuberkulose wêreldwyd. Die toename in pasïente wat chronies siek is, plaas openbare primêre gesondheidsorgfasiliteite onder toenemende druk om, binne die beperkte hulpbronbeskikbaarheid pasïente te help. Dit verminder op die beurt die hulpbronne wat gewy kan word aan ander aspekte van primêre gesondheidsorg, b.v. intervensie-strategieë soos voorkomende opleiding. Boonop ontvang die private- en openbare sektor 'n soortgelyke deel van die BBP vir gesondheidsorg, maar die private gesondheidsorgsektor diens slegs 'n fraksie van die bevolking. Hierdie ongelykheid tussen die privaat- en openbare gesondheidsektore blyk 'n groot uitdaging te wees wat die effektiewe bestuur van diabetes in die openbare gesondheidsorgstelsel belemmer. Eweneens is die voorkoming en behandeling van diabetes 'n ingewikkelde proses wat deurlopende en metodologiese sorg vereis om die aanvang of vordering van die siekte te voorkom. Ten spyte van die implementering van 'n nasionale diabetiese beleid in 2014, het die voorkoms van tipe 2-diabetes steeds toegeneem van die 4.5% in 2010 tot 7% in 2017. Daarbenewens het die persentasie van alle sterftes wat verband hou met diabeties in Suid-Afrika toegeneem van 5.1% in 2014 tot 5.5% in 2017. Hierdie toename in die voorkoms van tipe 2-diabetes, tesame met die verhoogde diabetesverwante sterftes, laat vrae ontstaan aangaande die doeltreffendheid van bestaande diabetesintervensies in die Suid-Afrikaanse diabetiese beleid. Die primêre navorsingsdoel van hierdie tesis is dus om bestaande intervensiestrategieë vir beleidsformulering te ondersoek ten einde diabetes in Suid-Afrika meer effektief te bestuur. Vanweë die ingewikkelde aard van die gesondheidsorgstelsel sowel as die nie-lineêre aard van interaksies binne die stelsel, is stelseldinamika gekies as 'n toepaslike modeleringsbenadering om diabetiese-beleidsintervensies te evalueer ten einde insig te bekom oor die oorsaaklike verband binne hierdie stelsel. Twaalf dinamiese hipoteses word voorgestel in die vorm van 'n oorsaaklike lusdiagram wat gebruik word in die ontwikkeling van 'n stelseldinamikamodel. Die Vensim DSS sagtewarepaketword gebruik om die dinamika van die volgende groepe te modelleer (i) nie-diabetiese bevolking, (ii) ongediagnoseerde en gediagnoseerde prediabetiese bevolking, (iii) ongediagnoseerde en gediagnoseerde diabetiese bevolking, en (iv) ongediagnoseerde en gediagnoseerde diabetiese bevolking wat ook komplikasies opgedoen het . Die effek van verskillende beleidsintervensies op die totale jaarlikse diabetiese-sterftesyfer word dan bepaal. Hierdie scenario's het die verandering van die hulpbrontoekennings aan die volgende intervensies ingesluit (i) die gesondheidsorgpersoon tot pasiëntverhouding, (ii) selfbestuuronderrig, (iii) lewenstylonderrig, (iv) keurings intervensies en (v) die beskikbaarheid van mediese hulpbronne. Die scenario-resultate word ontleed om noemenswaardige oorsaaklike verhoudings uit te lig, en hoëvlak beleidsoorwegings word na gelang hiervan voorgestel. Die werkverrigting van veral twee stelle intervensies is opmerklik, naamlik: (i) die kombinasie van die gesondheidsorgpersoon tot pasiënt-verhouding en selfbestuur-opvoedingsintervensies; en (ii) die kombinasie van die gesondheidsorgpersoon tot pasiënt verhouding en die beskikbaarheid van mediese hulpbronneintervensies. Die belangrikste oorsaaklike verband word egter tussen hierdie drie bogenoemde intervensies waargeneem | die gesondheidsorgverhouding tot pasiëntverhouding, selfbestuu onderrig en beskikbaarheid van mediese hulpbronne. Alhoewel daar getoon word dat intervensie wat op lewenstylonderwys fokus die totale sterftes per diabeet per jaar verminder, blyk hierdie intervensie nie in kombinasie met enige van die ander vier intervensies n kragtige uitwerking te hê nie. Nietemin is die intervensie vir lewenstylonderwys 'n effektiewe ondersteunende intervensie. Ten slotte, alhoewel dit bewys is dat die keuringsintervensie die doeltreffendste intervensie was om die ongediagnoseerde diabetiese sterftes per jaar te verlaag, is die impak van die keuringsintervensie op die ongediagnoseerde diabetiese sterftes per jaar beduidend minder as die impak van die ander intervensies op die diagnose van diabetiese sterftes per jaar.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/107271
This item appears in the following collections: