CLN - Feature

Critical Value Change

Labs consider pros and cons of implementing new hypoglycemia target based on limited evidence

Whitney J. Palmer

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In January 2019, the American Diabetes Association (ADA) in its annual standards of medical care in diabetes released new guidance, classifying level 2 hypoglycemia as a glucose value <54 mg/dL, the threshold at which “neuroglycopenic symptoms begin to occur and requires immediate action to resolve the hypoglycemic event” (Diabetes Care 2019;42(Suppl. 1):S61–70). This change, representing a new critical value, was based on a consensus report issued in 2017 by ADA and seven other organizations on standardizing clinically meaningful outcome measures beyond HbA1c for type 1 diabetes (Diabetes Care 2017;40:1622-30). Although the healthcare community generally hews closely to ADA standards, this move has been met with some doubt and disagreement among clinical laboratorians.

Conversation around the updated value perhaps has been more animated than other ADA recommendations because of the scant evidence behind it. The trail of references cited for the change eventually leads to a single 30-year-old study that involved only 10 people who did not have diabetes (Am J Physiol 1991;260:E67–74). For many in the field, that has called into question the need for a revised critical value, especially as making this change could create significant protocol pivots and shift workloads for laboratorians and providers alike, potentially straining already stressed resources.

Because monitoring patients’ glucose can play a critical role in many aspects of their medical care, clinical laboratorians are carefully considering whether to institute this new critical hypoglycemia value. With many factors involved, the decision will not be one-size-fits-all.

To Change or Not to Change

Clinical laboratories and institutions will need to decide for themselves whether the new critical value is appropriate, said Steven Cotten, PhD, DABCC, NRCC, FADLM, co-director of clinical chemistry at UNC Hospitals in Chapel Hill, North Carolina. At UNC, adopting the new value helped avoid any future misunderstandings or miscommunications about patients’ care, according to Cotten.

“We ended up aligning our values with the ADA hypoglycemia protocols with the understanding that the change wasn’t based really on a study,” he explained. “But we felt it was best to eliminate confusion.”

The ADA update also fell in line with an existing policy at Bronson Methodist Hospital in Kalamazoo, Michigan, said compliance and point-of-care coordinator Erika Deaton-Mohney, MT(ASCP). Bronson’s existing protocol for hypoglycemia was triggered above the critical value range, and a conversation had already begun about potentially changing the lab’s lower limit. Consequently, news of the ADA’s updated value accelerated the lab and clinical teams’ plan to switch from ≤42 mg/dL to ≤55 mg/dL.

Other institutions arrived at different conclusions about making the change, Houston Methodist Hospital in Texas among them. Consultation with other organizations indicated that raising the hospital’s critical value from 50 mg/dL to 54 mg/dL would not serve a clinical need, according to Roger Bertholf, PhD, DABCC, FADLM, director of clinical chemistry.

“Our laboratory leadership, including the director of clinical laboratories, wanted to know what other hospitals were doing,” he said. “When they heard the switch wouldn’t even be a change that would exceed the variability of glucose measurements on a glucometer, they lost a lot of enthusiasm for making the change.”

Adil Khan, MSc, PhD, director of point-of-care testing and clinical chemistry at Temple University Hospital and Temple University Episcopal Campus in Philadelphia, echoed Bertholf’s comments, adding that 54 mg/dL is more appropriate for clinical trials than patient care. In fact, he said, Temple uses a higher critical value, 60 mg/dL, because this threshold reduces the number of patients who experience negative outcomes, including fainting or a rapid, irregular heartbeat.

“A level of 54 mg/dL is more of a biochemically defined value where a patient would start to feel a lot of physiological issues. They develop an impaired mental status and many other symptoms,” he said. “After our endocrinologists spoke with their clinical colleagues, we felt we wanted our level to be higher.” Khan emphasized that any change to glucose critical values—regardless of the threshold chosen—should be made with improved patient care management in mind.

LAC+USC Medical Center in Los Angeles also has followed its own path on hypoglycemic critical values. Although the hospital flags as abnormal any glucose level <65 mg/dL, the organization’s critical value remains at <40 mg/dL, according to Allison Chambliss, PhD, DABCC, director of clinical chemistry and point-of-care testing.

“I don’t want to discount the fact that a glucose below 54 is certainly very low, and we know patients can be symptomatic and need intervention,” she said. “But for us, this discussion really came down to diagnosis or clinical classification, and that does not equal a critical value notification limit.”

The Journey to a Decision

Chambliss emphasized that deciding whether to switch a hypoglycemia critical value requires discussion and research. Any change also would call for methodical preparation because many parties, including both laboratory and point-of-care testing personnel, will be affected.

She also stressed the value in reaching out to peer institutions to see how they’ve approached this issue, including how they quantify and the reasoning behind their low glucose threshold. Bertholf seconded this recommendation, as the results of his poll of other organizations factored into Houston Methodist’s decision to maintain its current critical value.

Chambliss and her lab colleagues also gathered feedback from committees that involve providers who would receive the critical value calls. For instance, they collected input from the chairs of internal medicine not only at LAC+USC but also all USC hospitals, as well as from the health system’s ambulatory cases committee comprised of primary internal medicine providers and medical directors of outpatient clinics.

At Bronson Methodist, the patient safety and quality committee, as well as the medical process improvement and critical care process improvement committees, contributed to the decision-making process, said Deaton-Mohney.

Back at UNC, Cotten recommended involving stakeholders from pharmacy and information technology to ensure the smoothest transition. “As a large health system, we tried to make the change globally, so it wasn’t just our laboratory that had to do this,” he explained. “It was every single other satellite location, ambulatory clinic, affiliated hospital. They all had to coordinate on a single date to make the switch.”

Deaton-Mohney recommended that labs provide knowledge-sharing documents filled with details about how to make the change. This can be a good way to ensure all providers—particularly nurses most directly involved in patient care—are aware of the new critical value and how to implement it.

“The challenge is getting the education and knowledge out there about the change,” she said. “You also need to make sure your instrumentation at the point-of-care can trigger and alert the operator on the main screen to any critical results with the patient.”

Another place to get the word out is in daily patient care huddles, added Deaton-Mohney. “It can be a hurdle to make sure all of your operators that aren’t in the main laboratory understand this change and know what the differences are from old to new,” she said. “It’s critical to have your nursing team work with you, making sure they follow their processes to train all their operators.”

Chambliss also cautioned labs to consider how any changes to glucose critical values might impact their workflows. “Examine your retrospective data from your labs so you know what those glucose results have looked like in the past,” she said. “Having the data and being able to play with the numbers will let you know how many more patients you would be making calls for so you can assess any impact on both the lab and on providers.”

It’s also important, she added, to know not only who will be responsible for making the calls about patients with low values but also who will be asked to receive this information. The switch to a higher critical value could become burdensome on both ends of the exchange—clinical laboratory staff and clinicians. Workflow reviews also would need to consider any adjustments needed in systems to document critical value calls for regulatory purposes.

A solid plan based on detailed information-gathering will guide labs in their decision-making on this issue, Bertholf suggested. “If you’re starting from ground zero to establish a program, and you want to know what sort of procedures you will implement, it is always helpful to have some sort of guideline document to which you can refer,” he suggested. “That gives you some sort of basis for choosing a particular threshold—otherwise, it can be an arbitrary threshold based solely on clinical judgment rather than evidence.”

Whitney J. Palmer is a freelance journalist in Holly Springs, North Carolina. +Email: [email protected]