Table 1

Proportion of asthmatics with lung eosinophilia

StudyCase definition*MethodDefinition of eosinophilic and non-eosinophilic asthma based on cut off values**NoEosinophilic asthma
*All asthma cases were recruited from symptomatic patients attending a clinic, unless indicated otherwise; these studies therefore only give a crude estimate of the proportion of asthma which is characterised by lung eosinophilia in selected populations.
†Induced and spontaneous sputum.
‡Children with asthma symptoms not recruited through a clinic.
§Children with bronchial hyperresponsiveness (BHR).
¶In case the authors did not define a cut off or when a cut off of less than 2% was chosen in the original study, we have set the cut off at 2%.
**Cut off was determined based on eosinophil counts in control subjects unless indicated otherwise.
††30 obstructed ICS treated patients were included in the study but in the figure only 26 could be observed. Individual sputum data for the other three asthma groups (ICS treated non-obstructed and ICS naïve obstructed and non-obstructed patients) were not given in the article.
‡‡59 patients were included in the study but in the figure only 56 could be observed.
Studies in adults:
Fahy et al (1995)32Acute severe asthmaSputum2% eosinophils¶1850%
Turner et al (1995)24Mild asthma with exacerbation in past 2 weeksSputum†4% eosinophils¶3447%
Pizzichini et al (1996)27Stable asthmaSputum2% eosinophils¶1958%
Wenzel et al (1999)18Severe asthma, corticosteroid (CS) dependentBronchial biopsyMean eosinophil count +2SD (exact value not given)3459%
Pavord et al (1999)22Asthma patients treated with β2 agonistsSputum3% eosinophils¶2361%
Pavord et al (1999)33Asthma of variable severitySputum†3% eosinophils2688%
Jatakanon et al (1999)23Persistent asthma of variable severity:Sputum2% eosinophils5560%
• Mild persistent2378%
• Moderate persistent1638%
• Severe persistent1656%
Lemiére et al (1999)34Asthma of variable severitySputum2% eosinophils 633%
Berlyne et al (1999)30Asthma of variable severitySputum†2% eosinophils8452%
Mean eosinophil count + 2SD (87 × 103/g)8482%
Tarodo de la Fuente et al (1999)35Asthma of variable severitySputum2% eosinophils3834%
• Mild untreated 922%
• Moderate treated with ICS1225%
• Severe CS dependent1747%
Ordoñez et al (2000)36Acute severe asthmaTracheal aspirates during intubation2% eosinophils¶1070%
Wark et al (2000)37Asthma of variable severity:Sputum2.75% eosinophils3244%
• Not treated with ICS1567%
• Treated with ICS1724%
Giannini et al (2000)38Stable asthma treated with CS, currently asymptomaticSputum3.0% eosinophils3033%
Gibson et al (2001)21Persistent asthma, BHR, CS dependent:Sputum2.5% eosinophils5641%
• Mild persistent1127%
• Moderate persistent2646%
• Severe persistent1942%
Ottanelli et al (2001)39Stable persistent asthma treated with ICS with FEV1/FVC <70%Sputum2.0% eosinophils26††62%
Fahy et al (2001)40Moderate to severe asthmaSputum2.0% eosinophils56‡‡59%
Studies in children:
Gibson et al (1998)20Open population incl non-symptomatic subjects:Sputum2.5% eosinophils¶(162)(27%)
• Symptoms in past 2 weeks‡5641%
• BHR§2362%
Gibson et al (1999)41Acute severe asthmaSputum2.5% eosinophils3788%
Marguet et al (1999)19• Asthma with recurrent symptomsBAL2% eosinophils¶1457%
• Infantile wheezers (age 5–46 months)2619%
Wilson et al (2000)31Asthma of variable severity:Sputum2% eosinophils¶3619%
• Not treated with ICS2129%
• Treated with ICS15 7%
Gibson et al (2001)42Asthma defined as wheezing in last 12 months‡Sputum2.5% eosinophils2245%