Introduction

Primary health care (PHC) is essential for improving population health, reducing health disparities, and achieving greater health equity. The World Health Organization (WHO) and global health entities emphasize primary care as the "programmatic engine" for achieving Universal Health Coverage (UHC), health-related Sustainable Development Goals (SDGs), and health security [1]. Primary healthcare centers (PHCCs) are fundamental to effective health systems, acting as the first point of contact and providing essential services that contribute significantly to health outcomes, disease prevention, and health promotion [2,3]. However, the uneven spatial distribution of these centers often exacerbates health inequalities, particularly in underserved or rural areas). When primary care infrastructure does not align with population needs, vulnerable groups—such as rural residents or low-income populations—face barriers to access, leading to disparities in health status, survival rates, and overall longevity [3,4,5].

Despite these established benefits, equity in PHC resource allocation remains a critical challenge worldwide. Disparities in resource distribution and utilization often stem from complex social, structural, and economic factors [3,6-8]. Across many health systems, the spatial allocation of PHC facilities fails to align with true population needs, particularly in underserved regions [8,9]. Achieving equity in the distribution of PHC resources remains a global challenge, with disparities influenced by social, economic, and structural factors that hinder equitable access and utilization [3,9-13].

In Saudi Arabia, substantial progress has been made in expanding health care infrastructure, including primary healthcare facilities [14-16]. Despite these investments, disparities in resource distribution persist across regions, reflecting unequal access and potential inequalities in health outcomes. Existing studies have highlighted regional disparities in the distribution of health workforce and hospitals [17-26]. These studies demonstrate significant intra-regional and socio-spatial disparities in the distribution of physicians, dentists, and nurses across the Kingdom. While urban populations generally experience superior healthcare access compared to their rural counterparts—a gap largely driven by higher income and education levels, intra-urban inequities remain pronounced. Even within major metropolitan areas like Riyadh, neighbourhood-level variations persist regarding access to urgent and primary care services [13, 26]. Furthermore, regional progress remains uneven: while territories such as the Eastern Province have successfully expanded their primary healthcare (PHC) footprint, other regions continue to face resource deficits relative to their population burden, ultimately driving divergent health outcomes nationwide [13, 17,20]

To address these disparities, the Saudi government has prioritized primary care optimization under the aegis of Saudi Vision 2030 [27], the Health Sector Transformation Program (HSTP) [28]. These strategic policy frameworks aim to construct a comprehensive, integrated, and sustainable healthcare system that ensures fair geographical coverage—especially for rural and underserved populations. Achieving these ambitious national objectives requires evidence-based, targeted resource allocation. Evaluating the spatial equity and concentration of PHC infrastructure and human resources is therefore crucial to informing policy decisions and building a resilient primary care system in Saudi Arabia. Accordingly, the main objective of this study is to evaluate the spatial equity and geographic concentration of primary healthcare infrastructure and human resources across the Kingdom of Saudi Arabia.

Materials and Methods

Study Design and Data Sources

This study employed a descriptive analytical design to evaluate equity and structural concentration in primary healthcare (PHC) resource allocation across the 20 health regions of the Kingdom of Saudi Arabia from 2015 to 2022. Data were extracted from the annual Statistical Yearbooks [29] published by the Ministry of Health (MOH). The dataset included all 20 MOH health regions, portraying annual data for three core PHC resources: Primary Healthcare Centers (PHCCs), Physicians employed in PHCCs, and nursing staff employed in PHCCs. Likewise, regional population statistics for each corresponding year were obtained from the MOH Statistical Yearbooks. To account for missing region-specific population figures in the 2021 yearbook, linear interpolation was applied by computing the mean of the 2020 and 2022 population figures for each health region. Data cleaning, validation, and managing missing values were executed using Microsoft Excel, while statistical computations were performed using Stata (Version 14/SE, StataCorp, College Station, TX).

Measurement of Equity and Concentration Indicators

To rigorously measure distribution equity and resource concentration, two complementary economic indices were calculated: the Gini Coefficient and the Herfindahl–Hirschman Index (HHI).

1. Gini Coefficient (Lorenz Curve Analysis)

The Gini coefficient measures inequality in resource distribution relative to population proportions. Graphically based on the Lorenz curve, it quantifies the area between the line of perfect equality (the 45-degree diagonal) and the cumulative proportion of resources mapped against the cumulative population share [30].

The Gini coefficient (G) was calculated using Brown’s formula:

Where:

• X_i represents the cumulative proportion of the population in health region (ordered from lowest to highest per-capita resource share).
• Y_i represents the cumulative proportion of the healthcare resource (PHCCs, physicians, or nurses) in health regions
• n denotes the total number of health regions (n = 20).

Gini values range continuously from 0 to 1:

• < 0.20: Perfect or near-perfect equality
• 0.20 - 0.29: High degree of equality
• 0.30 - 0.39: Moderate inequality
• 0.40 - 0.59: Severe inequality
• 0.60 <: Absolute inequality

2. Herfindahl–Hirschman Index (HHI)

While the Gini coefficient measures equity relative to population density, the HHI assesses structural market/regional concentration of resources across the 20 health regions.

The HHI was calculated as the sum of the squared regional percentage shares for each health resource [31]:

Where:

• n represents the number of health regions (n = 20).
• Si denotes the percentage share of a specific resource (PHCCs, physicians, or nurses) located within region i.

The theoretical range of the HHI spans from near 0 up to 10,000 (where 10,000 indicates absolute concentration in a single region):

• < 1,500: Low concentration (highly dispersed distribution across regions)
• 1,500 - 2,500: Moderate concentration
• > 2,500: High concentration (heavy cluster of resources in few regions)

Results

Demographic and Descriptive Statistics

Between 2015 and 2022, PHC resources and population dynamics in Saudi Arabia underwent structural shifts characterized by facility consolidation alongside workforce expansion (Table 1). The national population increased by 2.07%, growing from 31,521,418 in 2015 to 32,175,224 in 2022.

The overall trajectory of primary healthcare facilities did not track population growth. The total number of PHCCs fell by 7.09% nationally (from 2,282 facilities in 2015 to 2,120 in 2022). Conversely, human resource capacity at the primary care level experienced steady expansion, with PHC physicians increased by 11.10% (from 9,647 to 10,718), and PHC nurses by 9.42% (from 18,745 to 20,510). The expansion of healthcare personnel relative to the reduction in physical facilities indicates a strategic consolidation toward larger, higher-capacity centers with greater provider density per facility.

Note: Data derived from Saudi Ministry of Health Statistical Yearbooks (2015–2022).

Regional Distribution and Availability Densities

At the regional level, substantial disparities were observed in density of health resources per 10,000 population across the 20 health regions (Table 2). High-density in urban areas consistently demonstrated lower per-capita resource ratios due to large population denominators, whereas smaller or more remote health regions exhibited higher per-capita resource availability. In 2022, urban centers such as Jeddah (0.2), Makkah (0.3), Eastern Region (0.3), and Riyadh (0.4) maintained lower facility densities, compared with less populated regions like Al Baha (2.7) and Bisha (2.0). Lower physician ratios were concentrated in Jeddah (1.9), Riyadh (2.1), and Makkah (2.5), whereas higher ratios were reported in Al Baha (10.9), Bisha (9.5), and the Northern Region (7.6). Availability of nursing staff followed a matching pattern, ranging from lower ratios in Jeddah (2.4), Makkah (3.8), and Riyadh (3.9) to higher ratios in Al Baha (17.9), Bisha (15.7), and Al-Jouf (15.6).

Table 4 shows that the density of PHCCs remained largely stable over the 8 years, maintaining an overall mean near 1.0 per 10,000 population. Regional disparities ranged from a low of 0.19 in 2016 to a high of 2.77 in 2021. With the improvement in medical coverage over time, the mean physician density rose from 3.88 to 4.76 per 10,000 population. However, regional inequality widened, peaking at a maximum density of 10.90 physicians per 10,000 in 2022 compared to a historic regional low of 1.37 in 2017. Nursing capacity recorded the largest net growth among healthcare resources, increasing its overall mean density from 8.34 to 9.82 per 10,000 population. It also displayed significant regional variance, reaching up to 17.95 nurses per 10,000 in 2022 versus a minimum of 1.45 in 2017.

Distribution Equity: Gini Coefficient Analysis

The Gini coefficient was calculated to measure equality in the distribution of PHC resources relative to regional population shares. Across all three resource categories, Gini index values remained below 0.30, indicating a high overall degree of distribution equality across the 20 health regions (Table 4).

PHCC Infrastructure showed high structural stability over time, maintaining a lower Gini range of 0.262 to 0.277 with a negligible standard deviation (0.001). Facility closures during the study period did not destabilize geographical equity. The analysis showed that physician distribution recorded lower baseline inequality than PHCCs and nurses, though it exhibited greater annual variability (SD = 0.010). However, the distribution of nursing staff demonstrated moderate inequality indices ranging from 0.197 to 0.269, with notable increases recorded in 2017 (0.254) and 2021 (0.269).

The Lorenz curves corresponding to the Gini coefficients for PHCCs, Physicians, and nurses in PHCCs from 2015 to 2022 are shown below:

Fig 1: Lorenz curves corresponding to the Gini coefficients for PHCCs, Physicians, and nurses in PHCCs from 2015 to 2022

The figure shows that physicians in PHCCs exhibit the lowest overall Gini coefficient (Mean G = 0.178), positioning their Lorenz curve closest to the line of perfect equality (45⁰ line). Physical PHCC infrastructure shows the greatest inequality (Mean $G = 0.269$). Nurses in PHCCs (Green Curve): Shows a moderate level of inequality with a mean Gini coefficient of 0.231.

Structural Concentration: Herfindahl–Hirschman Index (HHI) Analysis

The Herfindahl–Hirschman Index (HHI) was applied to assess absolute market and geographic concentration across the 20 regions. Benchmark HHI values below 1,500 represent low concentration (highly dispersed allocation), while values exceeding 2,500 signal high concentration.

Table 5 shows all computed HHI values are ranged between 734.05 and 984.36, confirming that primary healthcare resources in Saudi Arabia maintained a low degree of concentration across health regions throughout the 2015–2022 period. PHCC facilities remained the most essentially static resource, whereas physicians showed a temporary surge in concentration during 2018–2019, then rebalancing to 780.92 by 2022. Nurses displayed stable, low concentration indices overall (734.05 to 811.31), with no prolonged regional clustering observed.

Discussion

The findings of this study reveal that despite expansion of healthcare infrastructure, the distribution of primary healthcare resources in Saudi Arabia remains uneven, with regional disparities evident in the number of PHCs, physicians, and nurses per 10,000 population. The use of inequality indices such as the Gini coefficient and the Hirschman–Herfindahl Index (HHI) indicates moderate but persistent disparities, with certain regions experiencing temporary fluctuations. Notably, the Gini coefficients for PHCs and nurses suggest moderate inequality, while physicians tend to be more evenly distributed but with instances of instability—particularly during 2019 and 2021—possibly reflecting recruitment and retention challenges [29].

Earlier studies have pointed out imbalances in how primary healthcare facilities and hospital capacity are allocated throughout the Kingdom. Calculating the Gini coefficient to assess inequality, Al Sheddi et al. [2] demonstrated that PHCs were distributed relatively evenly across 20 health regions, yielding the Gini coefficients ranging from 0.2 to 0.3. Nevertheless, the authors observed localized inequities, highlighting that a more balanced allocation is essential for optimizing healthcare accessibility and patient outcomes. Similarly, Saffer et al. [23] identified regional inconsistencies in primary care center availability, noting a pronounced urban clustering of specialized medical personnel. Kattan [17] observed the geographical inequities in the distribution of PHCs during 2022. The study underscores an imperative for equitable healthcare accessibility across the Kingdom. Strategic expansion of primary care infrastructure is requisite in underserved territories to adequately align service capacity with population demand. Consequently, these empirical insights must be systematically embedded into institutional policy frameworks to advance the strategic objectives of Vision 2030, specifically regarding the establishment of a sustainable, equitable national health system.

The low HHI values across the years suggest that resource concentration remains generally dispersed; however, regional variations still impact equitable access. The regional disparities in healthcare workforce and infrastructure can negatively influence health outcomes, underscoring the importance of policy measures that focus on equitable distribution aligned with population needs [9,11,17-18]. Moreover, the slight decline in the number of PHCs despite population growth indicates a need for strategic planning to prevent service gaps, especially as demographic shifts and epidemiological transitions continue.

While Saudi Arabia has made significant progress in expanding primary healthcare infrastructure and workforce, ongoing regional disparities pose challenges to achieving true health equity. Strategic, data-driven resource allocation, targeted policy interventions, and innovative delivery models are essential to bridge the gap between urban and rural, and between high- and low-resource regions. These findings were collaborated by earlier studies in Saudi Arabia [16-17, 20,23,25]. Ultimately, these efforts are vital for realizing the overarching goals of Saudi Vision 2030 and ensuring that primary healthcare serves as an equitable foundation for sustainable health development across the kingdom.

To address the persistent disparities in primary healthcare resource distribution across Saudi Arabia, a comprehensive, data-driven approach is essential. Policymakers should prioritize strategic geographic allocation by utilizing detailed demographic and geographic data to identify underserved regions and adjust resource distribution accordingly. Expanding infrastructure and leveraging telemedicine in rural and remote areas can significantly improve access, while incentivizing healthcare professionals—through financial benefits, career development opportunities, and mandatory service policies—can help ensure a more equitable workforce distribution. Capacity building initiatives, including increased training programs and retention strategies, are vital to sustain workforce growth in underserved areas. Regular monitoring and evaluation using indicators like the Gini coefficient and HHI should be institutionalized to track progress and enforce accountability. Integrating these efforts within national development frameworks such as Vision 2030 and fostering collaboration with local communities and private sector partners will ensure services are culturally appropriate and tailored to regional needs. Additionally, innovative delivery models like mobile clinics and outreach programs, along with dedicated funding and performance-based incentives, can further promote equitable access. Implementing these multi-faceted policies will help create a more equitable, efficient, and sustainable primary healthcare system that effectively serves all regions of Saudi Arabia

Future research should focus on evaluating the long-term impacts of resource redistribution policies on healthcare access and health outcomes across different regions in Saudi Arabia. Additionally, studies exploring the effectiveness of innovative service delivery models, such as telemedicine and mobile clinics, in reducing disparities are needed. Investigating the barriers faced by healthcare professionals in underserved areas and identifying strategies to improve workforce retention and motivation can also provide valuable insights. Furthermore, incorporating patient perspectives and community engagement into research can help tailor policies to better meet local needs, ultimately contributing to a more equitable and resilient primary healthcare system.

Conclusion

This study provides a comprehensive evaluation of PHC resource allocation across Saudi Arabia’s health regions during a major health sector transformation. The findings reveal a structural shift toward resource optimization in primary care physical infrastructure experienced mild consolidation, while human workforce capacity expanded considerably, outpacing national population growth. The analysis confirms that macro-level equity and structural dispersion of PHC resources remain well-maintained nationwide. However, per-capita analyses underscore persistent regional imbalances. To fulfill the ambitions of Saudi Vision 2030, future healthcare policy must move beyond structural consolidation to address sub-regional and local demographic demands. Strategic interventions should focus on dynamic, population-adjusted workforce distribution and targeted infrastructure planning to ensure equitable, timely access to primary care for all communities.

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