Sue Hughes
October 16, 2023
The issue of earlier classification of medical conditions — known as “diagnosis creep” — is leading to many patients becoming eligible for treatments at earlier stages in their disease course, without those treatments having been validated in those particular groups.
This concern has been highlighted recently in the atrial fibrillation (AF) field, with the recent change in the definition of hypertension in the US at lower levels of blood pressure causing a lot more patients to become eligible for oral anticoagulation at an earlier stage in their AF course.
US researchers analyzed data from 316,388 patients with AF from the National Cardiovascular Data Registry Practice Innovation and Clinical Excellence (PINNACLE) outpatient quality improvement registry, and found that at 36 months follow-up, 83.5% of patients met the new 130/80 mm Hg definition of hypertension, while only 53.3% met the previous 140/90 mm Hg definition.
The diagnosis of hypertension gives 1 point in the CHA2DS2-VASc score, which is used to determine risk in AF patients, those with scores of 2 or more being eligible for oral anticoagulation.
The researchers report that in patients with an index CHA2DS2-VASc score of 1 (before the hypertension diagnosis), at 36 months, 83% fulfilled the 130/80 mm Hg definition of hypertension while the 140/90 mm Hg definition was met by only 50%, giving a large increase in the number of patients who could qualify for oral anticoagulation therapy.
“While the definition of hypertension has changed in response to landmark clinical trials, CHA2DS2-VASc was validated using an older hypertension definition, with limited ambulatory blood pressure monitoring and higher blood pressure goals for treatment,” the authors state.
“Now, patients with AF will meet the CHA2DS2-VASc threshold for oral anticoagulation earlier in their disease course. However, it is not known if patients with scores of 1 or 2 using the new hypertension definition have sufficient stroke risk to offset the bleeding risk of oral anticoagulation and will receive net clinical benefit,” they point out.
This study was published online as a research letter in JAMA Network Open on September 26.
Senior author of the report, Mintu Turakhia, MD, Stanford University/iRhythm Technologies Inc, said AF is a good example of how “diagnosis creep” may lead to patients receiving inappropriate treatment.
“Risk scores derived when risk variables were described in one way are starting to be applied based on a diagnosis made in a totally different way,” he told theheart.org | Medscape Cardiology. “Diagnosis creep is a problem everywhere in medicine. The goal of this study was to quantify what this means for the new definition of hypertension in the context of risk scoring AF patients for anticoagulation treatment. We are calling attention to this issue so clinicians are aware of possible implications.”
Turakhia explained that the CHA2DS2-VASc score was formulated based on claims data so there was a record of hypertension on the clinical encounter. That hypertension diagnosis would have been based on the old definition of 140/90 mm Hg.
“But now we apply a label of hypertension in the office every time someone has a measurement of elevated blood pressure — treated or untreated — and the blood pressure threshold for a hypertension diagnosis has changed to 130/80 mm Hg,” he said. “We are asking what this means for risk stratification scores such as CHA2DS2-VASc, and how do we quantify what that means for anticoagulation eligibility?”
He said that while identifying hypertension at lower blood pressures may be beneficial with regard to starting antihypertensive treatment earlier with a consequent reduction in cardiovascular outcomes, when this also affects risk scores that determine treatment for other conditions, as is the case for AF, the case is not so clear.
Turakhia pointed out that with AF, there are additional factors causing diagnosis creep, including earlier detection of AF and identification of shorter episodes due to the use of higher sensitivity tools to detect abnormal rhythms.
“What about the patient who has been identified as having AF based on just a few seconds found on monitoring and who is aged 65 (so just over the age threshold for 1 point on the CHA2DS2-VASc score)?” he asked. “Now we’re going to throw in hypertension with a blood pressure measurement just over 130/80 mm Hg, and they will be eligible for anticoagulation.”
Turakhia noted that in addition to earlier classification of hypertension, other conditions contributing to the CHA2DS2-VASc score are also being detected earlier, including diabetes and reduced ejection fractions that are considered heart failure.
“I worry about the sum of the parts. We don’t know if the risk score performs equally well when we’re using these different thresholds. We have to be careful that we are not exposing patients to the bleeding risks of anticoagulation unnecessarily. There is a clear issue here,” he said.
What Should Clinicians Do?
Commenting on this issue for theheart.org | Medscape Cardiology, Gregory Lip, MD, chair of cardiovascular medicine at the University of Liverpool, Liverpool, England, who helped develop the CHA2DS2-VASc score, said clinicians needed to think more broadly when considering hypertension as a risk factor for the score.
He points out that if a patient had a history of hypertension but is now controlled to below 130/80 mm Hg, they would still be considered to be at risk per the CHA2DS2-VASc score.
And for patients without a history of hypertension, and who have a current blood pressure measurement of around 130/80 mm Hg, Lip advises that it would be premature to diagnose hypertension immediately.
“Hypertension is not a yes/no diagnosis. If you look at the relationship between blood pressure and risk of stroke it is like a continual dose-response. It doesn’t mean that at 129/79 there is no stroke risk but that at 130/80 there is a stroke risk. It’s not like that,” he said.
“I wouldn’t make a diagnosis on a one-off blood pressure measurement. I would want to monitor that patient and get them to do home measurements,” he commented. “If someone constantly has levels around that 130/80 mm Hg, I don’t necessarily rush in with a definite diagnosis of hypertension and start drug treatment. I would look at lifestyle first. And in such patients, I wouldn’t give them the 1 point for hypertension on the CHA2DS2-VASc score.”
Lip points out that a hypertension diagnosis is not just about blood pressure numbers. “We have to assess the patients much more completely before giving them a diagnosis and consider factors such as whether there is evidence of hypertension-related end-organ damage, and if lifestyle issues have been addressed.”
Are New Risk Scores Needed?
Turakhia agreed that clinicians need to look at the bigger picture, but he also suggested that new risk scores may need to be developed.
“All of us in the medical community need to think about whether we should be recalibrating risk prediction with more contemporary evidence — based on our ability to detect disease now,” he commented.
“This could even be a different risk score altogether, possibly incorporating a wider range of parameters or perhaps incorporating machine learning. That’s really the question we need to be asking ourselves,” Turakhia added.
Lip noted that there are many stroke risk factors and only those that are most common and have been well validated go into clinical risk scores such as CHA2DS2-VASc.
“These risks scores are by design simplifications, and only have modest predictive value for identifying patients at high risk of stroke. You can always improve on clinical risk scores by adding in other variables,” he said. “There are some risk scores in AF with 26 variables. But the practical application of these more complex scores can be difficult in clinical practice. These risks scores are meant to be simple so that they can be used by busy clinicians in the outpatient clinic or on a ward round. It is not easy to input 26 different variables.”
He also noted that many guidelines are now veering away from categorizing patients at high, medium, or low risk of stroke, which he refers to as “artificial” classifications. “There is now more of a default position that patients should receive stroke prevention normally with a DOAC [direct oral anticoagulant] unless they are low risk.”
Turakhia agreed that it is imperative to look at the bigger picture when identifying AF patients for anticoagulation. “We have to be careful not to take things at face value. It is more important than ever to use clinical judgment to avoid overtreatment in borderline situations,” he concluded.
This study was supported by the American College of Cardiology Foundation’s National Cardiovascular Data Registry. Turakhia reported employment from iRhythm Technologies; equity from AliveCor, Connect America, Evidently, and Forward; grants from US Food and Drug Administration, American Heart Association, Bayer, Sanofi, Gilead, and Bristol Myers Squibb; and personal fees from Pfizer and JAMA Cardiology (prior associate editor) outside the submitted work. Lip has disclosed no relevant financial relationships.
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