Scant Evidence About Optimal Number of Patients for PCPs

Veronica Hackethal, MD

January 20, 2020

The optimal number of patients that primary care physicians (PCPs) should see is unclear because very little evidence exists on the issue, according to a systematic review published online January 20 in the Annals of Internal Medicine.

"Our principal finding is that the evidence about the association between panel size [ie, patient load] and aims of health care is surprisingly thin, given the importance of primary care panel size to all models of population-based care," write author Neil Paige, MD, MSHS, and colleagues. Paige is affiliated with the West Los Angeles Veterans Affairs Medical Center in California.

"The few available studies provide a signal that increasing panel size may be associated with modest worsening of clinical quality and patient experience.... Current recommendations about panel size are based more on historical experience than on evidence," they explain.

Research suggests that patient load varies widely among PCPs, from fewer than 1000 to more than 4000 patients per full-time PCP. Methods to calculate the optimal patient load vary but usually include balancing patient factors, such as cost, access to care, and quality of care, with provider factors, such as burnout and having enough time to see patients. These methods usually include only activities that involve face-to-face patient care; they do not include activities such as working in the electronic medical record, emailing patients, following up on test results, and care coordination.

To review available studies on the issue, the investigators searched Google in September 2019, as well as four databases from inception to October 2019. To be included, studies could have had any design as long as they were published only in English and they evaluated PCP patient load and its effect on provider burnout and/or aspects of quality healthcare, as defined by the National Academy of Medicine: safety, efficacy, patient-centeredness, timeliness, efficiency, and equity.

The analysis included 16 mostly cross-sectional studies (15/16) that evaluated the link between panel size and patient/provider outcomes. The researchers also included one interventional study and 12 simulation modeling studies. The latter exclusively evaluated the link between panel size and access to care. Studies were conducted in Veterans Affairs facilities, US academic medical centers, and Ottawa, Canada.

Although the studies suggest a link between increasing panel size and decreased quality of care, evidence supporting optimal panel size is of modest quality at best, according to the authors. Most studies showed variable links, no links, or negative links between increasing panel size and patient and provider outcomes.

Overall certainty of evidence was very low for safety, efficiency (including cost), equity, and provider burnout. It was low for efficacy (clinical quality), patient-centeredness, and timeliness (access to care and continuity). Modeling studies that used risk adjustment to evaluate access to care yielded moderate-quality results that suggested that including case mix and clinical conditions may improve access to care.

The sole interventional study evaluated panel size on access to care over a 4-month period. Results were judged to be of fair quality and suggested that weighting panels by age, sex, and type of insurance may improve access to care.

The authors mention several limitations. Many of the studies were cross-sectional and cannot provide information about whether increasing panel size causes worse outcomes. Also, included studies may have been subject to publication bias, and the search strategy used in the review may not have identified all studies on this topic.

In an accompanying editorial, Christin Sinsky, MD, and Marie Brown, MD, discuss current problems with the US healthcare system as it concerns PCPs. They bring up possible solutions and suggest rephrasing this study's question.

"Rather than asking, 'What is the ideal panel size in primary care?' we suggest reframing the question to 'What is the ideal practice model that results in the best outcomes for the entire US population?' " write Sinsky and Brown. Both are affiliated with the American Medical Association in Chicago, Illinois.

"We believe that a well-trained, well-resourced primary care team will make the most of society's investment in these physicians' training and will contribute to better experiences for patients and clinicians, lower costs, and better access to care," they add.

Care models need to incorporate practice characteristics, such as factors related to support staff, the extended care team, the regulatory environment, and physician autonomy in decision making. Ultimately, the US healthcare system needs to invest more in understanding a practice model that is currently dysfunctional for PCPs, according to Sinsky and Brown.

"The starkest conclusion to be drawn from Paige and colleagues' review is that the US health care system needs far greater investment in the science of practice," they write.

"The $3 trillion US health care industry is underperforming, in part because of underpowered primary care. As a consequence, primary care physician resources are being squandered," they stress.

The study was primarily funded by the Veterans Affairs Quality Enhancement Research Initiative. The study authors and the editorialists have disclosed no relevant financial relationships.

Ann Intern Med. Published online January 20, 2020.

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