We use a previously published, bottom-up time accounting approach (10) to estimate the level of workload for each primary healthcare service included in a comprehensive service package. The list of healthcare tasks (“services”) is based on the Ethiopian HEP optimization roadmap for 2021-2035 (9) (complete list in Additional file 1, table 1). This is a general primary healthcare service package with a broad range of services including immunization, antenatal care, family planning, nutrition, testing and treatment for both infectious and non-communicable diseases (NCDs), and routine preventive care and counseling. The analysis is run in R, based on the publicly available PACE-HRH software package (11).
Model structure
The detailed model structure is outlined in a different publication (10) and we summarize it here. The model calculates the total amount of direct clinical contact time (in minutes) required to meet all of the healthcare needs for a baseline population. We start with a population of 5,000 in 2020, which is the target population size that each primary healthcare facility (Health Post) is supposed to serve (9), although the actual catchment population varies depending on spatial distribution, varying fertility, and internal migration.
For each service, we break out the relevant tasks (e.g. testing, treatment, counseling), specify the relevant population to which this service applies (e.g. children under 5, pregnant women), the number of contacts with the health system to fulfill the service (e.g. 1 test per suspected malaria case), the amount of time to complete the task, and lastly, the incidence or prevalence rate to reflect the proportion of the relevant population in need of care. The relevant population and the incidence rate are used to calculate the number of people expected to receive the service each year, which is multiplied by number of contacts and the time per contact to get the total service time for each PHC service.
Administrative tasks, in-service trainings, community engagement, public health surveillance, travel, and related tasks can be optionally included in the model. For this study, we have chosen to focus on the population-based drivers of workload, so only include direct clinical care tasks.
We utilize a Monte Carlo simulation to estimate the expected time required for each task, and then sum all tasks to calculate the total clinical workload. The model includes both parameter uncertainty (the initial rate) and the stochasticity (year-over-year change) inherent in estimating future trends. The sampling occurs for parameters including fertility and mortality rates by five-year age groups, disease incidence rates, and time per contact (details of distributions in Additional File 1, Table 2).
We account for birth seasonality and time-varying conditions including malnutrition, tuberculosis (TB), malaria, and diarrhea by applying condition-specific seasonality curves to each relevant service. For example, birth seasonality is applied to antenatal care (ANC) visits, which requires 4 contacts with the health system. The seasonality curves are detailed in Additional File 1, Table 3 and offsets in in Additional File 1, Table 4.
To demonstrate the calculation method, Table 1 lists data inputs required by the model to compute total expected service time for a clinical task, using treatment for moderate acute malnutrition in under-five children as an example.
Table 1. Input parameters for task time calculations. Every clinical task in the model requires a set of inputs that are used in the time calculation. One example, for Amhara region, the task of treating moderate acute malnutrition in under-five children, is shown here. Incidence rate or prevalence rate are used as appropriate for the task being described. Annual change rates are calculated as a ratio to the prior year (i.e., 1.0 = no change)
Task time input parameter
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Example value
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Name of task
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Treatment for moderate acute malnutrition
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Relevant population
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Children aged 0 to 59 months
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Incidence/prevalence rate in the population
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41.5% of under-five children
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Number of contacts with the health system
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2 contacts for malnutrition treatment
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Time per contact with the health system
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5 minutes per contact
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Annual change in incidence/prevalence rate
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0.98
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Applicable seasonality curve
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Malnutrition
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Seasonality offset (months)
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0 for the first contact, +1 for the second contact
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Data collection and assumptions
We collected data for subnational modeling from a range of sources, depending on availability and quality. The model accounts for differences between regions across each of the key input variables described in Table 1 and uses the most localized data possible.
We utilized United Nations (UN) population estimates (12) for regions of Ethiopia by 5-year age bands, interpolated to 1-year cohorts and modeled future population pyramids based on trends in fertility and mortality. Fertility rates are based on DHS-reported regional fertility rates from 2019 (13). Mortality rates are sourced from the World Development Indicators (WDI) from 2020 (14). We calculated the annualized rate of year-over-year change from the most recent pair of consecutive observations. In the cases where recent trends conflict with long-term historical patterns or when we were uncertain about whether a rapid change can persist, we include additional historical data in calculating the annualized change rate to get a more stable trend.
Because population trends are a key driver of the model, we conducted a sensitivity analysis that compared the trend of annual change rates going back at least 10 years and up to 20 years.
We searched Google and Google Scholar for published research articles, national prevalence surveys, and surveillance surveys to gather data on regional disease incidence rates, annual change rates in disease incidence, and regional seasonality patterns for disease incidence. In cases where regional data were not published, but the disease is known to exist, we backfilled with national averages, based on the expectation that the national average is the next-best estimate for the region. Where the data are inconsistent, we use the most recent available and prioritize estimates found in population-based surveys and meta-analyses with random sampling techniques. Due to gaps in the literature, it was difficult to find reliable estimates for annual change rates in regional disease incidence. Accounting for local disease eradication efforts and long-term trends in disease prevalence, we assumed a moderate decline of two percent per year for the relevant infectious diseases. Assumptions for number of contacts are based on common practice, and minutes per contact are educated guesses, which were also validated by experts.
Detailed data sources for all model inputs are listed in Additional File 1, Table 5.
Model application
We forecast PHC clinical workloads at the regional level from 2021 to 2035. Ethiopia is composed of eleven National Regional States (regions) – Tigray, Afar, Amhara, Oromia, Somali, Benishangul-Gumuz, Southern Nations, Nationalities and Peoples’ Region (SNNPR), Sidama, South West Ethiopia Peoples’ Region, Gambela, and Harari – and two chartered cities – Addis Ababa and Dire Dawa. The Sidama region and the South West Ethiopia Peoples’ Region were split off from the SNNPR in 2019 and 2021 respectively. Due to the recency of these changes and the age of our data sources, we treat the Sidama region and the South West Ethiopia Peoples’ Region as part of SNNPR for expediency purposes; this should not be construed as an opinion on the changes to administrative borders.
We exclude Tigray and Afar in predicted clinical hours analyses because Tigray and parts of Afar have been affected by civil conflict from November 2020 to November 2022 (15,16). Displacement caused by the conflict has great implications for food security, healthcare needs and access to healthcare for the affected population. Prior to the onset of conflict, Afar had the highest overall fertility rates in the country and the fertility rates were increasing for the youngest age groups. The conflict could affect the age-group specific fertility and mortality rates in ways that are hard to predict, so making future estimates is inappropriate until the situation has stabilized and new data has been gathered.
We ran the model under two specifications. The first model specification imitates the reality in which the population continues to grow (12) and the fertility rates exhibit changes year over year consistent with historical trends. The second model specification fixes the population at 5,000 for all years in the simulation, to isolate the expected changes in clinical workload due to population structure shifts only. The analyses are based on simulated results from 100 trials for each model specification.
Even though fertility rate predictions are a key assumption in the model, it is uncertain whether future trends will mirror the recent history on which we have based our model parameters. Rates are known to change in response to a complex set of dynamics, including social norms, access to family planning, and girls’ education, and have been known to evolve in unexpected ways (17). To acknowledge this uncertainty about the future, we conducted sensitivity analysis to assess its impact on the predicted PHC workload. We reran the model using two different historical time periods for our parameters: 2011-19 and 2000-19, and a benchmark of moderate decline in fertility rates at 0.5% per year relative to baseline.
The analyses were completed using PACE-HRH (11) release version 1.0.2. The model was built in R Studio version 2022.07.2+576, using the R statistical programming language version 4.2.0. Code is publicly available on GitHub.