Primary care physicians saw a median of 1,370 unique patients over two years, with the interquartile range spanning over 2.5x, from 860 to 2,208 patients.
Physicians in metropolitan or micropolitan areas saw 85% more patients than those in rural areas.
Physicians in independent practice or other settings had 29% larger patient panels than health system or hospital-employed physicians.
Primary care services are the logical foundation of any healthcare system that is focused on preventive health. Because U.S. healthcare policy assumes that the primary care provider (PCP) is the gateway to primary care services, understanding the variance in patient panel composition has the potential to inform how primary care resources can be better allocated, especially given the backdrop of inadequate provider supply. Understanding this variance is increasingly important as both vertical and horizontal integration reshape primary care practice ownership and workforce shortages intensify. The implications extend beyond care utilization alone, as patient panel characteristics influence care continuity, health outcomes and the decreasing financial viability of independent primary care practices.
For decades, U.S. healthcare policy has presumed that PCPs are the cornerstone of the care continuum, acting as both patients’ first point of contact for preventive care and as the coordinator for more complex care needs. Access to primary care leads to improved health outcomes, reduced costs and slowed chronic disease progression.1,2 However, the U.S. is facing a growing shortage of PCPs, with projections estimating a deficit of up to 40,400 physicians by 2036.3
Notably, the structure and ownership of primary care practices have shifted considerably in recent years.4 Independent physician practices have increasingly been acquired by health systems, private equity (PE) firms and corporations, altering existing incentive structures, employment arrangements and care delivery expectations. Hospital-affiliated PCPs increased from 25.2% in 2009 to 47.9% in 2022, and at least 47% of physicians were employed by or affiliated with health systems in 2024, up from less than 30% in 2012.5,6 The ratio of independent to employed physicians shows geographic variance; for example, 71% of physicians in Indiana are employed.7 Notably, studies have found that negotiated rates for office visits were 10.7% higher for hospital-affiliated primary care physicians and 7.8% higher for PE-affiliated physicians compared to independent physicians.8
Beyond practice ownership or physician employment status, the specialization of PCPs, whether focusing on pediatrics, geriatrics or general practice, also shapes panel composition. Research examining panel size variations found differences by specialty.9 Geography also influences the number, demographic characteristics and health status of primary care patient panels. Rural primary care practices face unique challenges, such as more pronounced provider shortages, longer travel times for patients and populations with higher rates of chronic disease.10 In 2023, 92% of rural counties were designated as primary care health professional shortage areas (HPSAs), with 42.6M people living in these HPSAs. Although 20% of Americans live in rural areas, just 10% of physicians practice in rural areas.11 By 2037, the current supply of physicians is expected to meet only 68% of demand in rural areas.12
While each of these factors has been studied independently, less is known about how they interact to shape the patient populations that different types of PCPs serve.
Leveraging national all-payer claims and Provider Directory data, patient panels were examined among primary care physicians (MD/DO). In this analysis, patient panel size refers to the unique number of patients to whom a physician renders care in a two-year period.13 Analyses were conducted to understand variation in primary care physician panel size by employment type (hospital or health system vs. independent or other), provider type (adult primary care, pediatrics, geriatrics) and geography (urban vs. rural).
Independent practice physicians had 29% larger panels than their hospital or health system-employed counterparts. Physicians in independent practice or other settings had a median panel of 1,556 patients over two years compared to 1,202 patients for those employed by health systems or hospitals (Figure 1). The interquartile ranges were 964 to 2,541 patients for independent practice and 766 to 1,905 patients for health system or hospital employment.
Independent practices have more direct financial incentives to maintain larger panels as their revenue generally depends both on patient volume and visit volume. In contrast, hospital-employed physicians are salaried, and primary care within the hospital is considered a loss leader, rather than a profitable service line. Independent practices may also have greater flexibility in scheduling and fewer administrative burdens than health systems. Regardless of differing structures and incentives, the wide variation within each employment category was substantial, suggesting that employment structure alone does not determine panel size or capacity.
Panel sizes varied predictably across primary care specialties. Pediatricians maintained the largest panels with a median of 1,893 patients over two years, compared to 1,250 for adult primary care physicians and 967 for geriatric PCPs (Figure 2). Wide variation was also observed within each specialty, with interquartile ranges spanning 1,194 to 2,892 patients for pediatrics, 759 to 2,045 for adult primary care and 594 to 1,598 for geriatrics.
Primary care patient panels vary widely across practice settings, with employment status emerging as a crucial indicator. Independent practice physicians had 29% larger panels than hospital or health system-employed physicians. This difference likely reflects the differing financial incentives, notably primary care as the singular revenue source for independent practices and a loss leader for health systems. Independent practices face financial pressures despite larger panels, as they receive lower negotiated rates from insurers than hospital-affiliated providers, while operating without the economies of scale or cross-subsidization available to health systems. The combination of higher patient volume and lower per-patient revenue contributes to ongoing consolidation as independent practices face declining financial viability.
While geography influences panel size in logical ways, with urban physicians serving larger populations than rural counterparts, specialty does as well. Pediatric panels are larger due to the continuous influx of patients from births, shorter routine visits and standardized annual well-child care. Adult primary care panels are shaped by a combination of preventive guidelines that dictate when adults receive preventive screenings and availability or financial barriers that could discourage consistent primary care interaction. Geriatric panels are inherently smaller given that elderly patients require more frequent and complex visits for chronic disease management. Substantial variation within each category indicates that practice structure and operational factors strongly influence not only how many patients a physician maintains in their panel, but also the volume of care rendered to those patients.
These findings take on greater significance given the economic pressures that influence not just how and when, but whether patients access primary care. Nearly one-third of Americans have skipped medical care due to cost concerns, and more than 30% report not having a PCP due to high costs.14,15 With single coverage deductibles rising by 110% since 2010, outpacing wage growth, patients have become active healthcare consumers by seeking affordable and convenient alternatives.16 Often faced with the notion that a primary care-forward approach to care is not financially sustainable, patients increasingly weigh perceived costs against immediate need, often deferring preventive care and only seeking medical care when symptoms become acute or have progressed.
These “value” calculations are defining care-seeking patterns in ways that extend gaps between primary care engagement and shift patients toward episodic, lower-cost alternatives when they “need” care. Patients have historically relied on PCPs for guidance in navigating their healthcare journey, especially for referrals to specialists and follow-up tests and procedures. The increase in “transactional” care consumption based on convenience or cost makes this coordination increasingly difficult. The result undermines the continuity and prevention-oriented model around which traditional primary care is designed, making it increasingly difficult for PCPs to maintain stable patient relationships, monitor health outcomes over time, coordinate specialty referrals and manage chronic conditions effectively.
For policymakers, these findings point to something that Congress has discussed for decades but never enacted: physician payment reform. While the logic of the current resource-based relative value unit (RBRVU) system is unassailable – relative payments based on the physician’s time and effort, associated practice expenses, etc. – it is completely misaligned with the notion of the primacy of primary care.
Logically, a system focused on encouraging the utilization of primary care services guided and overseen – but not always delivered – by a PCP would reimburse comprehensive care based on the societal and economic value of reducing the use of specialty care services as opposed to the current model that equates value to time.
While such an approach is objectionable to specialty societies, Congress was elected to serve every American, not protect the incomes of a select few. If Congress is unwilling to transform the RBRVU system, it should not expect a different outcome.