1. Study Design and Participants
This study utilized a systems thinking and modeling method grounded in the system dynamics approach. System dynamics, indeed, is a mathematical modeling method that assesses the behaviors of complex systems over time, leveraging tools from systems thinking. Furthermore, system dynamics models employ differential equations to handle the modeling of variables that change over a specified time period, feedback mechanisms, interactions, various delays, and also address issues related to simultaneity or reciprocal causation of system behaviors (14).
In this context, this study was conducted in five primary stages, drawing from the system thinking and modeling method proposed by Maani (15). These stages include: problem structuring; causal loop modeling; dynamic modeling; model formulation and scenario development; and implementation and organizational learning.
This report constitutes the third phase of a research project titled “Developing HS Scenarios for Iran using a System Thinking Approach”. In the first phase, key variables within the HS were identified through a scoping review and review of upstream documents. These identified variables were then categorized based on the BSC framework (16). In the second phase, these variables were presented in the form of a questionnaire to academic experts and professionals familiar with the HS’s issues and dimensions. This was done to determine the variables’ importance and uncertainty based on the existing context. To complete the cross-impact analysis (CIA) matrix in the MicMac software, the most significant variables and uncertainties of Iran’s HS, along with their mutual relationships, were extracted (17). Finally, the researchers decided to model the HS’s dynamics based on the identified causal relationships between the variables, aiming to depict the current and ideal state of the HS.
2. Model Structure
The study “Identification of Drivers, Uncertainties, and Future Scenarios of Iran’s HS” (17) served as the foundation for the stock and flow diagrams and the system dynamics model. In the stock and flow diagram, the HS was conceptualized based on the BSC framework (18), encompassing four dimensions: population health, service delivery, financing, and growth and development/infrastructures (including beds, medical equipment, and manpower). These dimensions encapsulate factors and relationships that can facilitate the delivery of efficient and effective health services, tailored to societal needs and demands.
2.1. Dimensions of Population and Population Health
The common population model is fundamentally employed in terms of population and population health. The population section comprises the basic components driving population change, namely birth and death rates. Both births and deaths are presumed to influence the current state of the population. A high number of births lead to population growth, which subsequently results in more births. This feedback loop is referred to as an amplifier in system dynamics. Conversely, an increase in population leads to more deaths, and a high death rate results in a decrease in a country's total population. This inverse relationship between population and mortality is known as the implicit goal or balanced feedback loops (Figure 1).
In this study, the birth rate was calculated as 0.013, and the death rate as 0.0064 percent in 2021. Based on these rates, the current population was projected for the next 10 years. It is important to note that the relevant demographic information was sourced from the Iranian Statistics Center (Appendix No. 1).
In the subsequent step, the current population was categorized into two groups: a population at risk and a population not at risk. These categories were determined by multiplying the current population by the degree of exposure/non-exposure to risk factors..
Figure 1. Demographic sub-model in Iranian HS modeling
Risk factors are divided into behavioral risk factors (such as nutritional status, physical activity level, addiction and smoking, depression and psychosocial stress, violence and sexual disorders) and biological risk factors (chronic disorders such as high cholesterol, high blood pressure, diabetes and obesity). Other risk factors are considered in three categories: factors related to people’s lifestyle in terms of cultural, economic and social aspects; natural and environmental hazards; and the efficiency and effectiveness of the HS (Figure 2). According to the included studies, the influence coefficients of each of the main components on the occurrence of risk factors were obtained first. Then, the influence coefficients of the sub-components on the corresponding component were obtained. Finally, by multiplying all the available coefficients for each sub-component, its influence on the occurrence of risk factors was extracted (Appendix No. 2).
Figure 2. Population health sub-model in Iranian HS modeling
2.2. Dimensions of Service Delivery
This dimension addresses the population’s demand for the HS. It is postulated that both the at-risk population and the non-at-risk population will contract disease and will seek both outpatient and inpatient services from the HS. In this study, the outpatient rate in the healthy population exposed to risk is 0.33, and in the healthy population without exposure to risk factors, it is 0.06. The hospitalization rate in the healthy population exposed to risk is 0.1, and in the healthy population without exposure, it is assumed to be 0.01 (Appendix Number 3). The adjustment of the current outpatients and inpatients in this dimension will be based on the deaths that occurred at a fixed rate and specific to each case (Figure 3).
Figure 3. Service delivery sub-model in the modeling of Iran's HS
2.3. Growth and Development /Infrastructures Dimension
2.3.1. Beds and Medical Equipment
Bed capacity is crucial for accommodating patients who require hospitalization as prescribed by their physicians. The annual rate of bed development and its attrition rate will regulate the number of beds in the system. Additional funding is required from public healthcare providers for the procurement and expansion of beds.
Medical equipment, a significant proportion of which is imported, is crucial for providing diagnostic services to both inpatients and outpatients. The pace of equipment development is largely contingent upon the budget allocated and the rate of inflation. The quantity of existing equipment within the HS is adjusted in accordance with the rate of attrition. This study discusses the most important medical equipment in use, including MRI machines, linear accelerators, CT scanners, angiography units, Gamma cameras, and others.
It should be noted that the index of the quantity of active medical beds/equipment within the HS is calculated using the occupancy rate and their current count. Considering the mentioned index facilitate planning and decision-making regarding service delivery, budgeting, and outsourcing of services to the private sector (as depicted in Figure 4).
In this dimension, the infrastructure costs of the health sector are calculated as a component of the total costs. This calculation is a composite of the expenditures on hospital beds, medical equipment, and the fundamental infrastructure costs in this sector for the initial year of calculation.
The coefficients considered in this dimension are derived from the country’s statistical database of 2021. The estimation of certain variables is based on the study conducted by Aghajani et al. in 2016. The annual growth rate of the bed is 0.001, the bed occupancy rate is 0.9, the growth rate of medical equipment is 0.0667, and the occupancy rate of medical equipment is assumed to be 0.6 (Appendix No. 4).
Figure 4. Sub-model of bed and medical equipment infrastructures in the modeling of Iran's HS
2.3.2. Manpower
In general, health production capital is defined as the physical and human capital invested for health status. This includes physicians, bed facilities, medical equipment, hospital buildings, and many other factors. For the sake of brevity, this study discusses the structure of the physicians’ education system and the current demand for physicians in the HS.
On the right side of the model, it is initially assumed that students will be admitted to the general professional doctorate level at a fixed rate, based on societal demand and existing educational capacities. A fee will be incurred for their education. A portion of the expenses spent on health education and research is allocated to the training of students in other medical fields.
Ultimately, some general medical students either withdraw and leave the educational system, work in the HS, or continue their education and study in one of the specialized fields. Similarly, students in specialized fields either leave the education system or engage in activities and service provision in the HS. In fact, the number of current physicians in the HS, which is the sum of general and specialist physicians, will be adjusted by their exit and retirement rates.
In the left side of the model, the working capacity of physicians is determined by taking into account the standard visit time and the time spent in outpatient and inpatient services. The demand for, and need of, physicians in the health sector is then ascertained based on the number of outpatients and inpatients in the system. In this dimension, a discrepancy has been identified between the supply of physicians in the health sector and their demand. This discrepancy has been examined over different years to identify periods of deficit or surplus (Figure 5).
In this dimension, the costs associated with medical education and health research are also considered. These costs are a combination of expenditures for general practitioners, health specialists, graduates of other medical fields, and the initial cost of education in the base year of calculation.
The coefficients used in this dimension have been extracted from news sites (for variables such as the number of candidates for the national entrance exam, the number of applicants for medical sciences, the capacity to accept fields, etc.), the statistics site of the Medical System Organization, and the 2021 statistical database of the country.
In this dimension, the current number of working physicians is 101,847; their retirement rate is 0.015; the number of employed nurses is 1.5 times the number of physicians; the number of dentists is 0.28 per physicians; and the number of pharmacists is considered equal to 0.19 times the number of physicians (Appendix No. 5).
Figure 5. Manpower sub-model in the modeling of Iran's HS
2.4. Financing Dimension
In this dimension, initially, on the right side of the model, the country’s gross domestic product (GDP) is discussed. A portion of it is allocated to healthcare costs, taking into account the annual inflation and exchange rate. On the left side of the model, in accordance with the financing process, the number of individuals requiring services, the number of inpatient and outpatient visits, the cost burden created by patients in outpatient and inpatient departments (average cost per visit), and the cost resulting from the provision of paraclinical and pharmaceutical services are considered. The sum of these costs is referred to as the medical costs incurred in the HS. Additionally, it is necessary to consider all the following costs: a) hygiene sector and the prevention and primary healthcare system; b) infrastructure development of the health service delivery system, including investment in beds and medical equipment, as well as manpower training; and c) overhead and support costs. Ultimately, the sum of these costs will form the current costs of the HS.
It should be noted that each year, the inflation rate in the health sector, which is essentially a percentage of the current cost, is added to the current price and determined as the overall cost of health. Ultimately, a discrepancy has been identified between the two aspects of the need for financial resources and the provision of the required financial resources. This discrepancy has been examined over different years to identify periods of deficit or surplus (Figure 6).
The figures included in this dimension have been extracted based on the statistical database of the Social Security and Health Insurance Organizations of Iran, the tariff for diagnostic and therapeutic services, the Statistical Center of Iran, the Central Bank, and the estimate based on the national health accounts in 2021 (Appendix No. 6)
Figure 6. Financing sub-model in the modeling of Iran's HS
3. Policy Experimentation
System dynamics simulations were conducted under three scenarios: desirable, intermediate and undesirable This study considers the change in health sector costs as the objective of these scenarios. Influential parameters such as the physician-to-population ratio, bed-to-population ratio, medical equipment-to-population ratio, health sector inflation rate, exchange rate, health’s share in GDP, GDP growth rate, management and support costs rate in the HS, level of exposure to risk factors, and population change factor were altered to test policies and demonstrate potential effects over the next decade (2021-2031) under these scenarios (refer to Table No. 1).
This study discusses the results of various simulations through desirable and undesirable interventions that determine the percentage increase or decrease compared to the base value. Changes in parameters were based on existing studies in the field or determined during the focus group discussion (FGD).
Table No. 1 - Potential Scenarios in Iran’s HS
Regarding the variable "exposure to risk factors," the current situation in 2021 was reported as 0.35. Consequently, expert opinions on the desirable and undesirable scenarios were precisely set at 0.2 and 0.45, respectively. To attain these levels, it is imperative to implement meticulous modifications in the sub-components of the variable, either through augmentation or reduction. The areas most likely to undergo transformation in the next decade were discerned and systematically incorporated into the targeting table, complete with precise change coefficients. This compilation epitomizes a sophisticated policy package (refer to Table 2).
Table No. 2- Change of parameters associated with health-related risk factors in each scenario, in order of the possibility of greater variability in the next ten years