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Table 3 Association (z-value; p trend) of FEV1 %predicted with CRP quartile classes§

From: Circulating alpha1-antitrypsin in the general population: Determinants and association with lung function

  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
  1. *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].