Sputum cell counts to manage prednisone-dependent asthma: effects on FEV1 and eosinophilic exacerbations

Abstract

BackgroundPrednisone dependence in asthma is usually described based on clinical and spirometric characteristics. It is generally believed that these patients have frequent exacerbations and lose lung function rapidly because of uncontrolled airway eosinophilia.ObjectivesThe objectives of this study are to report the effect on asthma exacerbations and the change in lung function over time in prednisone-dependent asthma when severe asthma is managed using a protocol that aims to maintain normal sputum cell counts.MethodsA retrospective survey of patients prospectively assessed in a university tertiary care asthma clinic.Results52 patients (30 males, mean age 51 years, 64% non-atopic) were followed for a median period of 5.4 years (min–max: 0.2–35.2). Monitoring with the aim of keeping sputum eosinophils below 3% resulted in higher doses of corticosteroids (median daily dose of prednisone was 10 mg and for inhaled corticosteroids was 1500 μg of fluticasone equivalent) than at baseline and this was associated with predictable adverse effects. Despite the disease severity, 10 patients (19%) did not require LABA for symptom control. Most importantly, over the period of follow-up, there were only 0.3 eosinophilic exacerbations/patient/year. Overall, there was an increase in FEV1 over the period of follow-up (mean +84.6 ml/year) rather than an expected decline.ConclusionsMonitoring of eosinophils in sputum enables to maintain symptom control and preserve FEV1 in patients with severe prednisone-dependent asthma.

Increase in blood eosinophils during follow-up is associated with lung function decline in adult asthma

“…In previous studies, rates of post-BD FEV 1 decline have varied from 38 mL y −1 for asthmatics compared to 22 mL y −1 in healthy subjects, 25.7 mL y −1 and 27.1 mL y −1 in severe asthma [14,29], 31.5 mL y −1 in asthmatic patients with frequent exacerbations vs 14.6 mL y −1 in those with infrequent exacerbations [13], 28.4-39.7 mL y −1 in adult nonsmoker asthmatic patients in the Busselton cohort [11], to 16.1-21.5 mL y −1 in ICS treated asthmatic patients [30,31]. Decline in our secondary care population, with 27.5 mL y −1 , is consistent with the observations reported in other populations.…”

Asthma Endotypes and an Overview of Targeted Therapy for Asthma

“…In RCTs in adults, moderate-to-severe asthmatics managed by normalizing induced sputum eosinophils had significantly reduced exacerbations and hospital admissions when compared with those managed by national asthma guidelines ( 23 , 55 ). When this strategy was applied clinically in 52 OCS-dependent asthmatics, maintained symptom control, reduced exacerbations, and preserved lung function was observed over 5 years ( 56 ). Novel biologic therapies should be considered for their steroid sparing effect, also for the minority of patients who are corticosteroid-insensitive (unresolved sputum eosinophilia despite high doses of oral corticosteroids) ( 57 ).…”

Asthma and Corticosteroid Responses in Childhood and Adult Asthma

“…A recent study recommended monitoring eosinophils in the sputum of patients with severe, prednisone-dependent, asthma as a means to maintain symptom control, reduce exacerbations and preserve FEV1 in these patients (112), however this remains technically difficult in clinical practice.…”