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 United States 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.
U.S. researchers analyzed data from 316,388 patients with AF from the National Cardiovascular Data Registry Practice Innovation and Clinical Excellence 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.
Senior author of the report, Mintu Turakhia, MD, Stanford (Calif.) 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 said in an interview. “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.”
Dr. 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.
Dr. 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.”
Dr. 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.