Expertise levels and experience of the human observers.

a<p>level of expertise based as on Reference <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042227#pone.0042227-tenCate1" target="_blank">[24]</a>: <i>I</i> has knowledge and some skills, <i>II</i> acts under full supervision, <i>III</i> acts under limited supervision, <i>IV</i> acts without supervision, <i>V</i> supervises and teaches;</p>b<p>Years since the observer started reading and evaluating chest CT scans; Observer 1 to 5 were considered ‘less experienced observers’ and observer 6 to 8 were considered ‘experienced observers’.</p

Flow diagram of the study.

<p>Flow diagram showing the selection of the study population from the total screening trial cohort. The index test presented is for the observer with the highest positive predictive value.</p

Comparison between the included subsample of participants and the total cohort of screening participants in the study period between July 2007–September 2008.

<p>Comparison using Mann-Whitney U test revealed no significant differences between the two groups.</p>a<p>data in the randomly selected subsample of male participants;</p>b<p>data in the total group of male participants screened in the study period</p

Diagnostic performance measures with 95% confidence interval for CT-based evaluation of COPD presence.

<p>Data given are percentages.</p><p><i>PPV</i> positive predicted value; <i>NPV</i> negative predictive value</p

Characteristics of the 266 study participants.

a<p>airflow limitation was defined as FEV₁/FVC ratio less than 70% and classified as mild (FEV₁≥80%), moderate (50%≤FEV₁<80%) and sever (FEV₁<50%);</p><p>SD = Standard deviation; FEV₁ = forced expiratory volume in the first second; FEV₁/FVC = ratio of FEV₁ over forced vital capacity</p

Intra- and interobserver agreement for CT based identification of COPD.

<p>Data given are Kappa (κ) values.</p