News Release

Substantial discrepancies found between estimated and measured GFR

Embargoed news from Annals of Internal Medicine

Peer-Reviewed Publication

American College of Physicians

1. Substantial discrepancies found between estimated and measured GFR


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A cross sectional study found that substantial discrepancies exist between individual estimated glomerular filtration rate (eGFR) and directly measured GFR (mGFR). Laboratory reports that provide eGFR calculations should consider including the distribution of this uncertainty. According to the authors, renaming the eGFR as a population average GFR (or paGFR) merits further discussion. The findings are published in Annals of Internal Medicine.


GFR is the standard metric used to assess and monitor kidney function. Directly measured GFR, or mGFR, requires injecting a filtration marker and measuring plasma or urinary clearance by serial blood and urine sampling under standardized conditions is not possible for every patient. So eGFR calculated from serum creatinine is often used by clinicians to predict an mGFR. Population-level discrepancies between eGFR and mGFR are low, but individual discrepancies are much higher. It is important to understand the magnitude of these individual-level differences for clinical decision making.

Researchers from the University of Mississippi Medical Center calculated eGFR from serum creatinine alone and cystatin C and creatinine using the Chronic Kidney Disease Epidemiology Collaboration equations for 3,223 participants and compared their eGFR to their mGFR to quantify the magnitude and consequences of the individual-level differences between the two. The authors found substantial discrepancies between directly measured GFR and estimated GFR and report that these differences resulted in only approximately 50% agreement between CKD stages. Individual-level differences between the mGFR and the eGFR did not improve substantially using cystatin C. The authors estimate that several factors contribute to these discrepancies: creatinine and cystatin C have non-GFR factors influencing their serum concentration; variability in the mGFR can result from normal physiology and measurement error from mGFR markers and technique; and as GFR estimation models the ratio of mGFR–body surface area as a function of serum markers, it incorporates errors in mGFR and errors in body surface area calculated from height and weight. According to the authors, their findings highlight the need to make direct GFR measurements available to patients who need them. They note that implementation studies are needed in this area, and research is needed to assess how the availability and use of mGFRs change clinical management.

Media contacts: For an embargoed PDF, please contact Angela Collom at To speak with the corresponding author Tariq Shafi, MBBS, MHS, please contact Karen Bascom at


2.  Interventions based on social needs may reduce hospitalizations, health care use


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A randomized study of adult Medicaid patients suggests that social program-based interventions for housing, food security, and transportation may reduce inpatient admission rates by 11 percent and emergency department visits by 4 percent. However, health care savings based on these interventions may not cover the cost of social the social programs. The findings are published in Annals of Internal Medicine.

Health care-based programs assisting patients with social needs including housing, transportation, and food security are gaining interest as a strategy to improve health and avoid unnecessary health care use, but uncertainty remains about their impact. The success of programs may vary depending on factors including patient eligibility, personnel qualifications, and enrollment duration.

Researchers from Contra Costa Health Services and University of California, Berkeley School of Public Health studied adult Medicaid enrollees in Contra Costa County, CA, at elevated risk for health care to assess the population level impact of a case management program designed to address patients' social needs. The patients were randomly assigned to 12 months of social needs case management or the control group. However, only 40 percent of those assigned to the intervention program chose to engage in case management. The researchers found that the intervention programs saved $3,423,085, or 17 percent of yearly program expenses, in hospitalization costs. The intervention also reduced total inpatient admissions by 11 percent and total emergency department visits by 4 percent. According to the authors, the observed effect on inpatient admissions, and even more pronounced reduction in avoidable admissions, may suggest that the intervention supported better management of chronic conditions. They also report that feedback from participating case managers suggested that the program helped patients build trust with the health system, resolve basic social needs, and better navigate the care landscape. The authors caution that although the interventions saved health care use, they may not save enough money to cover the cost of intervention programs.

Media contacts: For an embargoed PDF, please contact Angela Collom at To speak with the corresponding author, Daniel M. Brown, MPH, PhD, please contact Brittany Paris at


3.  Guidelines experts present framework for developing living practice guidelines in health care

Since the COVID-19 pandemic, guidelines that are updated as new evidence emerges are increasingly used



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Guidelines experts reviewed existing research and conducted their own to present a framework for developing living practice guidelines in health care. The framework provides specific instruction for the planning, production, reporting, and dissemination of such guidelines and highlights the considerations specific to each of those areas in the context of a living document. The advice is published in Annals of Internal Medicine.

Rigorously developed, disseminated, and implemented practice guidelines promote health, prevent harm, encourage best practice, and reduce practice variation. Since the COVID-19 pandemic, living practice guidelines, or those that are updated as new evidence becomes available, are increasingly being used to ensure that recommendations are responsive to rapidly emerging evidence.

A team of 51 multidisciplinary researchers from the Living Guidelines Group studied methods papers and conducted a review of handbooks of guideline producing organizations and an analytic review of selected living practice guidelines to develop a framework that characterizes the processes of development of living practice guidelines in health care.  The framework builds on the Guidelines International Network–McMaster guideline development checklist to address aspects specific or particularly relevant to the living guideline process. The researchers provide definitions of key concepts used in developing living practice guidelines and detail 4 specific areas -- planning, producing, reporting, dissemination, and accessibility. They explain that the planning process should address the organization's adoption of the living methodology as well as each specific guideline project. The production process consists of initiation, maintenance, and retirement phases. The reporting should cover the evidence surveillance time stamp, the outcome of reassessment of the body of evidence (when applicable), and the outcome of revisiting a recommendation (when applicable). The dissemination process may necessitate the use of different venues, including one for formal publication.

According to the authors, the framework should help guideline developers in both planning and conducting their living guideline projects.

Media contacts: For an embargoed PDF or contact information for an author, please contact Angela Collom at


New content also published in this issue:

Antinucleocapsid Antibodies After SARS-CoV-2 Infection in the Blinded Phase of the Randomized, Placebo-Controlled mRNA-1273 COVID-19 Vaccine Efficacy Clinical Trial

Dean Follmann, PhD; Holly E. Janes, PhD; Olive D. Buhule, PhD; Honghong Zhou, PhD; Bethany Girard, PhD; Kristen Marks, MD; Karen Kotloff, MD; Michaël Desjardins, MD; Lawrence Corey, MD; Kathleen M. Neuzil, MD, MPH; Jacqueline M. Miller, MD; Hana M. El Sahly, MD; and Lindsey R. Baden, MD

Original Research


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