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The correlations are weaker when looking at asthmatics during times of stability
(Grootendorst, Sont et al. 1997; Ronchi, Piragino et al. lggT). No relationship was
demonstrated with steroid dose or lung function test results in over 100 stable asthmatics and
40 normal subjects in one community sample of adults (Iouis, Sele et a\.2002). Eosinophils
were frequently within the normal range and not a useful diagnostic tool in a population
divided into 'normal subjects', 'asthmatics', 'wheeze but no asthma' and 'industrial exposure
to irritants' (I-emiere, Walker et al. 2001). Eosinophils, ECp, MBp, EDN and IL5 correlated
with methacholine challenge and FEVr in adult asthmatics (Pizzichini ,Pizzichiniet al. 1996).
However, the eosinophil numbers only accounted for 167o of the variance of the methacholine
challenge across one group, while the TNFo levels correlated more closely (Obase, Shimoda
et al. 2001). Other studies showed no correlation between eosinophilic inflammatory
parameters and lung function (Hashimoto, Minoguchi et al. 1999; Rosi and Scano 2000),
methacholine (Rosi and Scano 2000) or histamine challenges (Iredale, Wanklyn et al. 1994;
Hashimoto, Minoguchi et al. 1999). Eosinophils, leukotriene Ea (LTE+), ECp and rantes were
all increased in poorly controlled asthmatics rather than being consistently high in severe
asthmatics, for example if patients were well controlled (Romagnoli, Vachier et al. 2002).In
addition, they were high only with symptoms even in long-term corticosteroid dependent
patients (Tarodo de la Fuente, Romagnoli et al. 1999). Considerable heterogeneity in sputum
counts were seen in over 250 adult asthmatics and normal subjects with eosinophils of all
amounts (Green, Brightling et al.2OO2).
Many studies have used sputum to determine the best predictor of response to steroids. When
commencing longer term IHCS treatment in placebo controlled trials, sputum eosinophils
correlated to the response in a number of studies (van Rensen, Straathof et al. 1999; Aldridge,
Hancox et al. 2002: Deykin, Lazarus et al. 2005; Brightling 2006) and was a better marker
than ECP levels in either sputum or blood (van Rensen, Straathof et al. 1999; Rosi, Ronchi et
al. 2000; Aldridge, Hancox et al. 2002: Deykin, Lazarus et al.2o05), baseline lung function
@eykin, Lazarus et al. 2005) or methacholine challenge results (van Rensen, Straathof et al.
1999; Deykin, Lazarus et al. 2005). Acutely, sputum eosinophils and ECp fell with oral or
intravenous steroid treatment (claman, Boushey et al.lgg4; Rosi, Lanini et al. 2002) with the
eosinophil count giving a positive predictive value of 68Vo, sensitivity of 54Vo and specificity
of 76Vo for an increase in FEVr >l5%o with steroid therapy (Little, Chalmers et al. 2000).
Eosinophils, neutrophils, ECP, IL5 and fibrinogen all increased when treatment was reduced
but the eosinophil count was consistently the most accurate, across a number of studies, to
predict when treatment reduction would lead to symptom development (Pizzichini, pizzichini
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