Clinical score predicts risk of severe asthma exacerbation trajectory
medwireNews: Researchers have devised and validated a clinical risk score that accurately identifies asthma patients who will have persistently frequent severe exacerbations over the long term.
“Knowing the illness trajectory of a patient early in their clinical course allows clinicians to intervene at the earliest timepoint with the intent of altering the future trajectory,” the researchers point out in Allergy.
The team studied the rate of severe exacerbations warranting hospitalization or an emergency department (ED) visit over a 5-year period among 177 patients presenting to a specialist clinic with problematic asthma, encompassing both uncontrolled and severe disease. All of the patients were on step 4 of the Global Initiative for Asthma treatment ladder.
The patients fell into three distinct trajectories. The majority, at 58.5%, had stable disease and rare intermittent exacerbations (Trajectory 1, “infrequent”), while 32.0% had frequent severe exacerbations at baseline that gradually declined over the following years (Trajectory 2, “non-persistently frequent severe exacerbations”), and 9.5% had, on average, frequent severe exacerbations in every year (Trajectory 3, “persistently frequent severe exacerbations”). This last group had the highest rate of near-fatal asthma, at 0.28 events per 5 person–years versus 0.06 and 0.01 events per 5 person–years for Trajectories 1 and 2, respectively.
Probability of assignment indicated that patients were well matched with their assigned trajectories and there was no change in the trajectories after taking into account age, gender, ethnic group, and current smoking.
Patients in Trajectory 3 could be distinguished from those in the other trajectories according to six variables and these were used to compose a clinical risk score.
Two points were awarded to those with at least two ED visits or hospitalizations and requiring systemic corticosteroids for at least 3 days in the past year, while a history of non-fatal asthma, a body mass index of 25 kg/m2 or above, obstructive sleep apnea, gastroesophageal reflux, and depression each carried 1 point.
A score of at least 3 points predicted a high risk of being in the unfavorable third trajectory, with 72.2% sensitivity, 81.1% specificity, and an area under the receiver operating characteristic curve (AUC) of 84.0%.
“The components of the risk score are easy to use in clinical practice and had excellent performance in an independent validation cohort,” report Anthony Yii (Singapore General Hospital) and colleagues.
This validation cohort consisted of 84 patients and looked at exacerbation data spanning 3 years. At the same cutoff of 3 or more points, the clinical score predicted persistently frequent exacerbations with 100% sensitivity, 71.3% specificity, and an AUC of 94.0%.
The researchers propose that “assessing future risk of severe exacerbations using long-term trajectories can complement existing state-of-the-art clinical phenotyping and molecular endotyping approaches in tailoring asthma treatment.”
While cross-sectional phenotyping can inform on the most effective treatments to use, a trajectory-based approach “may help identify patients […] for whom specialist care and advanced treatments are the most indicated,” they conclude.
By Lucy Piper
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