Peak expiratory flow, rather than forced expiratory volume in 1 second (FEV1), is effective in predicting long-term asthma control following a reduction in daily inhaled corticosteroid (ICS) dose, according to research published in The Journal of Allergy and Clinical Immunology: In Practice.
Japanese researchers prospectively assessed adults with asthma from 6 hospitals across Japan’s National Hospital Organization, with a primary goal of measuring clinical symptoms following a 50% reduction in daily inhaled corticosteroid (ICS) dose.
Over 36 months, 213 patients recorded morning and evening measurements of peak expiratory flow. Additional measured parameters included serum IL-10 and IL-33 levels and thymic stromal lymphopoietin in all patients, as well as lung function, bronchial hyperresponsiveness, fractional nitric oxide levels, sputum eosinophil level, and serum IgE levels in most patients.
Nearly 60% of patients maintained asthma control for 3 years following ICS dose reduction. The factors most predictive of asthma control maintenance included low serum IL-10 and IL-33 levels, low peak expiratory flow variability over 1 week, and onset of asthma prior to age 10 years (P <.01, P =.35, P =.014, and P =.03, respectively).
“[W]e confirmed that high [peak expiratory flow] variability — rather than a 1-time measurement of FEV1 or maximum expiratory flow rate at 50% of forced vital capacity — is predictive of loss of control of asthma after ICS dose reduction,” the researchers wrote. “We consider that the change in [peak expiratory flow] over 1 week reflects the asthma control achieved over several days, whereas change in FEV1 after inhaled [short-acting beta agonist] represents disease control on that particular day only.”
They concluded, “We have demonstrated that…an adult with asthma will remain in control of the asthma for months to years after a 50% reduction in daily ICS dose.”
Tsurikisawa N, Oshikata C, Sato T, et al. Low variability in peak expiratory flow predicts successful inhaled corticosteroid step-down in adults with asthma [published online December 6, 2017]. J Allergy Clin Immunol Pract. doi:10.1016/j.jaip.2017.10.036