Table 3

Association (z-value; p trend) of FEV1 %predicted with CRP quartile classes§


z-value#
 ptrend (across crp quartiles)
Non-smoking men


FEV1 (% predicted)*
-3.91
 <0.000
FEV1 (% predicted)**
-4.53
 <0.000
Non-smoking women



FEV1 (% predicted)*
-2.32
 0.02
FEV1 (% predicted)**
-2.15
 0.03
Smoking men


FEV1 (% predicted)*
-2.44
 0.015
FEV1 (% predicted)**
-4.82
 <0.000
Smoking women



FEV1 (% predicted)*
-2.44
 0.015
FEV1 (% predicted)**
-3.14
 0.002

*controlled for BMI, systolic blood pressure, ETS (in non smokers), packyears (in smokers), alcohol intake, study area; ** crude associations; ¶additionally adjusted for menopausal status, and intake of female hormones; subjects with crp > 10 mg/l were excluded; §CRP quartiles (Q) (mg/l): Q1 < 0.6, Q2 < 1.1, Q3 < 2.2, Q4 > 2.2; # Regression models without CRP quartiles as predictor variable were computed first. A Cuzick's trend test was then used to test whether regression residuals showed a monotonous association with CRP quartiles. Under the null hypothesis of no trend, the z-value of Cuzick's trend test statistic approximately follows a standard normal distribution, enabling the computation of approximate p-values; a negative sign indicates an inverse association between CRP and FEV1%predicted [15].

Senn et al. Respiratory Research 2008 9:35   doi:10.1186/1465-9921-9-35