WED 11:30 AM Parallel Session: Disease Epidemiology and Strategy

Full Report: The paper explores the use of system dynamics modeling to challenge some key assumptions about the growth in demand and influence policy in two District Health Boards (DHBs) in the North Island of New Zealand. These two case studies show the power of system dynamics to challenge the assumptions, driven by linear thinking, that drive a lot of healthcare planning. All around the world, health services are under stress. Demand is increasing, costs are rising, and there is an increasing shortage of the staff and facilities needed to respond. The response is often to call for more resources: governments are being asked to increase funding, employers are being asked to increase salaries to attract more staff, and staff are asking for more resources to meet their current challenges. In addition, changing lifestyles are producing epidemics in conditions such as obesity and type 2 diabetes, which further increases the volume of people wanting a response from an already overloaded health service. The case studies highlight that, despite external pressures, much can be done by the providers themselves. Not all the problems are caused by rising demand and shortage of resources. At least some of the pressure is self induced. In these two cases, historical investment patterns and clinical practices drive current problems. The future, at least in these two examples is not predetermined by external pressures, but modifiable by internal policies. It was important therefore that the model was seen to have both clinical and financial validity. Steps were taken based on what is known about good collaborative modeling practices:

        The detailed model, based on the concept model shown above, was developed in conjunction with the local renal team, hospital management, and primary care providers. Key people developed the model structure as well as reviewed the numerical data that populated it.

        The model was populated with data taken from a number of sources, including the ANZDATA registry, DHB population data, data from a review of the literature, and the "informed judgments" of clinical and management staff involved. Because of the multiple data sources, any areas of uncertainty and/or debate were discussed with those involved in the modeling before being accepted as a model parameter.

        The model behaviour was mapped against historical data.

As a result the model had validity in the eyes of the managers and clinicians involved in developing it; they became spokespeople for its value. This was a powerful driver of change as the voice was now a combined clinical/managerial one.

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Modeling the Dynamics of Immunization Healthcare Systems: The Ugandan Case Study

Synopsis: The paper applies system dynamics modeling to better understand immunization health care problems and to generate insights that may increase the immunization coverage effectiveness. A causal loop diagram representing the immunization system is presented, out of which a model is designed with the intent to show how particular variables influence immunization demand and coverage. The paper builds on earlier papers by the same authors. Model analysis demonstrates the need to upgrade the health system in proportion to the growing population, and how this can lead to improved immunization coverage rates. The paper suggests key leverage points which could substantially improve immunization demand and the effectiveness of the health system as well as vaccine management.

Full Report: The authors initiated this study with the aim of understanding immunization health care problems, generating insights that may increase the immunization coverage effectiveness, and developing and simulating a healthcare policy design model by applying the system dynamics modeling approach. This research covered the activities, strategies and policies associated with immunization coverage. Modeling techniques as well key activities employed in health care modeling processes were investigated.

Explorations of the relationships, dynamics and processes of the current immunization system were done to establish how these factors influence insufficient demand and poor immunization coverage. Vaccine management, health care service provision and the program management at both national, district and village levels were examined. Specific in-depth investigations of the issues pertaining to immunization demand were carried out in Mukono district. The study employed the Dynamic Synthesis Methodology (DSM).

DSM uses a research design that combines two powerful research strategies: the qualitative (case study research method) and quantitative (system dynamics modeling) techniques to provide solutions to problems. Combining simulation and case study methods as proposed by the Dynamic Synthesis Methodology is beneficial in that the strength of the case study enables the collection of data in its natural setting. Factors affecting immunization coverage as well as national immunization policies used for immunization coverage were critically analyzed. The model was built based on the field study results which provide a descriptive model on which the system dynamics conceptual feedback structure is developed. The feedback structure model was developed with the help of causal loop diagrams. Preliminary causal loop diagrams generated from the data collected from the field studies were presented to various stakeholders for their comments and feedback from which a final causal loop diagram was developed.

The model shows that the current level of access to healthcare services is not sufficient to meet the growing population. The level of accessibility of healthcare services currently at forty-nine percent should be increased. The nurse to patient ratio currently at one to three-thousand-sixty-five should be increased to meet the required standard of one to on-hundred-twenty-five. The level of monitoring of health services should be increased through the adoption of technologies to improve the quality of immunization services. The research suggests that in order to have a well-suited immunization and community-based health initiative in developing countries, there is need to develop community health monitoring information systems that have procedures to track individuals by recording events and needs as services are extended to the communities. The success of a health information system depends on whether it meets the requirements of the stakeholders, which necessitates a deeper understanding of the organizational environment such as the one provided by system dynamics. A broad, integrated view of the immunization system provides an analysis of the complex interactions between behavioral, technical, policy and cultural issues which foster communication among the stakeholders by linking up the non-technical view and technical view of the designers and programmers of information systems by capturing the requisite information.

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Women with HIV/AIDS in Malawi: The Impact of Anti-retroviral Therapy on Economic Welfare.

Synopsis: The paper provides a preliminary, in-depth qualitative analysis of the plausible feedback mechanisms contributing to the high HIV/AIDS rate amongst young Malawian women by examining the relationship between HIV/AIDS infections, HIV risk categories, economic welfare (and productivity), and the potential impact of increased access to antiretroviral therapy (ART). For each model structure, the formulation processes involved were reviewed. The authors hypothesize that ART is fundamental to increasing economic welfare of young, HIV-infected women in Malawi and show that the models do provide useful information and feedback for future discussion on social policy and problem-solving..

Full Report: To better understand the situation on the ground in Malawi, to focus our perspective on vulnerable populations, and to shed light on an often overlooked group, the research and model-building focus on women between the ages of fifteen and twenty-four living with HIV/AIDS, thereby elucidating the interactions of various key factors and creating a roadmap for effective policy discourse and alternatives for poverty reduction amongst this target population. The research provides a preliminary, qualitative, in-depth analysis of the plausible feedback mechanisms contributing to the high HIV/AIDS rate amongst young Malawian women by examining the relationship between HIV/AIDS infections, HIV risk categories, economic welfare (and productivity), and the potential impact of increased access to antiretroviral therapy (ART).

Detailed causal loop diagrams help to tease apart the complicating factors contributing to the complexity of this issue and help to highlight that the issue as a whole is more than just the sum of its parts. While the current model is clear, informative, and helpful, additional steps are needed to strengthen its usefulness and capacity to better inform policy discussions and decisions. Addressing the limitations of the current model would be one important step to improving its potential for use. Some of the key factors constraining this model are the exclusion of prevention strategies and treatment measures other than ART, other potential limiting model boundaries, the use of a reference mode which assumes every infected Malawian in our target population will become unproductive, and  the exclusion of the intricacies of international aid, national debt, and potential long-term dependency.

The paper has the potential of entering the Malawian government, private not-for-profit agencies working in Malawi, international funding sources, as well as research institutions into new discussions on the causal loop relationships and feedback mechanisms involved in this particular dynamic problem. This paper can also be used toward gaining a clear understanding of areas of need, areas of limited research and data, as well as toward building a cost-benefit analysis. Ultimately, this paper will help in the search to find answers (and in the search to discover appropriate questions) to complex social problems, such as women with HIV/AIDS in Malawi, and jumpstart the critical discussions necessary to tackling such integrated, multifaceted social problems. This paper may also help test and illustrate the long reach that gender inequity has, with consequences not just for women, but for nations as a whole. Once levels of healthy productivity are attained, women with HIV/AIDS can then begin striving for long-term goals, such as poverty reduction strategies including asset building and micro-financing. Increased productivity of women living with AIDS leads to increased economic welfare for a large percentage of the population, which ultimately leads to increased economic welfare of the country as a whole. However, it deserves reiteration, that such long-term goals simply cannot be attained until women are able also to reach their short-term priorities.

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Ahmad T Azar

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