The report is a product of the VA/HSR&D Evidence Synthesis Program.
Systematic Review: What is the Optimal Panel Size in Primary Care?
In 2009, the VA Handbook 1101.02—Primary Care Management Module (PCMM) established a baseline panel size of 1,200 patients for a full-time physician in a Patient Aligned Care Team (PACT). This number could be adjusted up or down based on the availability of support staff, number of examination rooms, and patient complexity. After adjustment for these factors, panels ranged from 1,000 to 1,400. In 2017, VA Directive 1406—Patient-Centered Management Module (PCMM) for Primary Care reaffirmed both the baseline panel numbers and adjustment parameters.
Primary care providers (PCPs) want to provide high-quality, comprehensive care to their panel of patients. However, determining the right size panel - to ensure that providers have the time to do all their tasks - is a problem that has yet to be solved. External factors like physician shortages contribute to the problem when systems suggest that panel sizes need to be increased to cover more patients in the face of inadequate numbers of PCPs. Such processes may contribute to burnout by not allowing providers adequate time to perform their required tasks. Thus, determining the right or optimal panel size for a full-time physician and team is a complex undertaking that requires balancing the demands of the system (i.e., patient access to care, clinical effectiveness or quality, patient experience, and cost) with the needs of the provider team (i.e., physician/team satisfaction, adequate time for care, and avoidance of physician/team burnout). Further, a standard method for determining panel size does not account for the tasks that occur outside of traditional face-to-face clinical visits, including patient communication (i.e., telephone calls, emails, and form completion), test follow-up, panel management activities, and care coordination.
Investigators with VA's Evidence Synthesis Program in West Los Angeles, CA conducted a systematic review to help inform an expert panel that will consider issues about determining VA primary care panel size. Investigators conducted searches in PubMed (inception to 3/8/19), Web of Science (inception to 3/10/19), as well as Scopus and Embase (1/1/18 to 3/8/19). Using Google, they also searched the gray literature. The literature search produced 462 potentially relevant articles; of these, 30 publications met initial inclusion criteria, including 16 hypothesis-testing studies that assessed the association of panel size with an outcome of interest, 11 studies of models, and 3 of toolkits.
For this systematic review, the Institute of Medicine (IOM) framework for quality healthcare was used as the source of potential measures that could be considered for optimization. The IOM framework has six "Aims for Improvement
;" healthcare must be: 1) safe, 2) effective (operationalized to include clinical quality), 3) patient-centered (which included patient experience measures), 4) timely (operationalized to include access and continuity), 5) efficient (operationalized to include cost), and 6) equitable. To these six aims, investigators added reducing provider burnout.
Summary of Review
The evidence about the effect of panel size on IOM aims for healthcare improvement is surprisingly thin, given the importance of primary care panel size to all models of population-based care. The evidence consists of a handful of cross-sectional studies that assess associations of panel size with clinical quality, patient experience, access and continuity, and show variable, no, or negative associations of increasing panel size on these outcomes of interest. The few studies available provide a signal that increasing panel size may have an association with modest worsening of clinical quality and patient experience. Several modeling studies exist, but all model only the effect of panel size on access to care and assume that other IOM aims are constant with increasing panel size. Modeling studies support the policy that risk-adjustment and practice-level variables influence the optimal panel size for access. Current recommendations regarding primary care panel size are based more on historical experience than on evidence.
Applicability to VA Patients
Four of the studies in this systematic review were done in VA populations. However, even these studies use VA data that are 5-10 years old, and primary care delivery in VA has been changing rapidly (e.g., PACT), suggesting that the results of these VA studies may already be out of date. It also is important to note that many non-VA studies assume that beneficiaries of a commercial insurance plan or Medicare will primarily use that insurance. This is not necessarily the case in VA, as Veterans receive care in VA as an entitlement, not as an insurance benefit. Therefore, it is possible that they also have another primary insurer - and another primary care physician. How this might influence VA primary care provider panel sizes is unclear.
The nationwide adoption of the team-based PACT model may have fundamentally changed the panel capacity that providers are able to manage. Historical panel size norms from several decades ago, like the target panel size of 1,200 patients, may no longer be relevant to current VA practice. Additional research on the relationship between panel size and PACT team-based care is needed.
A substantial amount of research is needed before declarations of what constitutes an "optimal" panel size in primary care can claim to be evidence-based. VA is well-positioned to conduct this research due to the existing availability of its rich sources of data. First, more evidence needs to be accumulated about the effect of changes in panel size on the IOM aims other than access. A potential first step would be assessing this within the VA healthcare system by using clinical quality and patient experience outcomes data; for example, individual measures of cancer screening, vaccination, tobacco use, diabetes, and hypertension. A next step would be an assessment of experimental changes in panel size on clinical quality, access, and patient experience, etcetera.
Evidence also is needed regarding primary care provider burnout - and about the appropriate visit frequency or follow-up time, and format (i.e., face-to-face, video or telephone, or secure messaging), for patients with chronic conditions. Most currently used visit frequencies or follow-up times (such as a visit frequency of twice a year for a patient with well-controlled diabetes and hypertension) are based on historical norms, are variable between physicians, and lack evidence that a particular frequency produces better outcomes than some other frequency.
Shekelle PG, Paige NM, Apaydin EA, Goldhaber-Fiebert JD, Mak SS, Miake-Lye IM, Begashaw MM, Beroes-Severin JM, What is the Optimal Panel Size in Primary Care?: A Systematic Review. Washington, DC: Evidence Synthesis Program, Health Services Research and Development Service, Office of Research and Development, Department of Veterans Affairs. VA ESP Project: #05-226; 2019.
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