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For assessing stroke risk, changes in validated atrial fibrillation risk predictors over time are far more accurate than baseline predictors alone, a study showed.

When researchers in Taiwan examined Delta-CHA₂DS₂-VASc, which reflects changes in the risk predictor scores, this prediction strategy was found to be strongly predictive of ischemic stroke risk.

The findings confirm that the CHA₂DS₂-VASc scores of atrial fibrillation (Afib, AF) patients are not static, wrote researcher Tze-Fan Chao, MD, of Taiwan's Taipei Veterans General Hospital, and colleagues, in the Journal of the American College of Cardiology, published online Jan. 8.

Just over half of the patients included in the analysis developed new comorbidities during the study, most commonly hypertension.

Introduced in 2001, for patients with atrial fibrillation assigns one point each for congestive heart failure, hypertension, age ≥75 years, and diabetes mellitus, and two points for a prior stroke or transient ischemic event.

Roughly a decade later, the prediction tool was modified to include vascular disease, age, and sex (, which improved stroke prediction. This model is now widely recommended to guide clinicians and patients as make decisions about anticoagulation therapy.

In their newly published study, Chao and colleagues examined three ways of using the CHA₂DS₂-VASc score to predict stroke risk: baseline CHA₂DS₂-VASc score, follow-up CHA₂DS₂-VASc score, and the change in the score over time, known as Delta CHA₂DS₂-VASc.

"Because the CHA₂DS₂-VASc score would change over the follow-up period, we hypothesized the risk change (Delta CHA₂DS₂-VASc) could have greater predictive value by assessing stroke risk factors with a dynamic assessment for new and/or incident comorbidities," the researchers wrote.

The researchers examined national universal health insurance data on 31,039 Afib patients in Taiwan who had not received antiplatelet treatments or oral anticoagulants and who did not have comorbidities other than age and sex associated with CHA₂DS₂-VASc at baseline.

Delta CHA₂DS₂-VASc scores were defined as differences between the baseline and follow-up CHA₂DS₂-VASc scores.

The mean baseline CHA₂DS₂-VASc score was 1.29, compared to 2.31 during follow up, with a mean Delta CHA₂DS₂-VASc score of 1.02. The score remained unchanged in 40.8% of patients.

Among the 4,103 patients who suffered ischemic strokes during close to 172,000 person-years of follow-up:

• 89.4% had a Delta CHA₂DS₂-VASc score ≥1 compared with only 54.6% of patients without ischemic stroke

• 64.4% of patients had ≥1 new-onset comorbidity, with the most common being hypertension (50.3% of patients)

• 35.4% developed congestive heart failure, while 14.4% developed diabetes mellitus

• 49.9% developed one new comorbidity, while 36.5%, 12.1% and 1.4%, respectively, developed two, three and four new comorbidities

"In this real-world, nation-wide Taiwan AF cohort, we clearly demonstrated that the CHA₂DS₂-VASc score is not static, and that most patients with AF who experienced ischemic stroke develop one or more new stroke risk factors before presentation with ischemic stroke," the researchers wrote.

In an editorial published with the study, Brian Gage, MD, who led the team that developed the CHADS₂ stroke model, wrote that the new findings make a clear case for reassessing CHA₂DS₂-VASc score periodically, "at least for low-risk patients who are not prescribed anticoagulant therapy."

"Clinicians who are accustomed to recalculating the periodically for their patients who are not prescribed a statin will find this recommendation familiar," he wrote. "It may also sound familiar because some AF that, 'individual risk varies over time, so the need for anticoagulation must be re-evaluated periodically in all patients with AF.'"

Gage, of the Washington University School of Medicine in St. Louis, Missouri, noted that additional research is needed to validate the Delta CHA₂DS₂-VASc score and to better explain the strong link between a rising score and stroke risk.

It also remains to be seen, he wrote, how adoption of the risk change model will impact patient outcomes.

"For example, would use of a Delta CHA₂DS₂-VASc score increase the appropriate use of anticoagulant therapy? Or would it obfuscate prescription of stroke prophylaxis? More importantly, how would use of a Delta CHA₂DS₂-VASc score affect clinical outcomes? Because answers to these questions are unknown, potential use of the proposed Delta CHA₂DS₂-VASc score awaits further research," Gage wrote.