A Simple Score for Future Risk Prediction in Patients with Controlled Asthma Who Undergo a Guidelines-Based Step-Down Strategy.

Abstract

The minimum controlling dose of treatment must be established in patients with asthma, but the outcome of step-down is unpredictable. To identify factors associated with risk of control loss when stepping down asthma treatment and to develop a score to predict this risk. A prospective, multicenter study including adults with well-controlled asthma was performed. Treatment was stepped up or stepped down over a 12-month period to maintain asthma control. We determined associations between clinical and functional variables and step-down failure. Finally, we derived a score to predict loss of control in 1 cohort and validated it in an independent cohort. The derivation cohort consisted of 228 patients; 218 completed at least 1 step-down episode and a total of 495 step-down episodes were evaluated. A medical-record documented postbronchodilator spirometry result of <70% forced expiratory volume in 1 second (FEV₁)/forced vital capacity (odds ratio [OR] = 2.08; 95% confidence interval [CI]: 1.26-3.43), current FEV₁ < 80% (OR = 1.80; 95% CI: 1.03-3.14), ≥1 severe exacerbation in the previous 12 months (OR = 2.43; 95% CI: 1.48-4.01), and Asthma Control Test score < 25 (OR = 2.30; 95% CI: 1.35-3.92) were independently associated with failure. The score showed an area under the curve of 0.690 (95% CI: 0.633-0.747; P < .05) in the derivation cohort and 0.76 (95% CI: 0.643-0.882; P < .001) in a validation cohort of 114 patients. A score <4.5 implies a low risk of failure (<20%), whereas a score >8 implies a high risk (>40%). This score can facilitate the prediction of step-down failure before medication taper in patients with well-controlled asthma.