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      The COPD assessment test correlates well with the computed tomography measurements in COPD patients in China

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          The chronic obstructive pulmonary disease (COPD) assessment test (CAT) is a validated simple instrument to assess health status, and it correlates well with the severity of airway obstruction in COPD patients. However, little is known about the relationships between CAT scores and quantitative computed tomography (CT) measurements of emphysema and airway wall thickness in COPD patients in the People’s Republic of China.


          One hundred and twelve participants including 63 COPD patients and 49 normal control subjects were recruited. All participants were examined with high-resolution CT to get the measurements of emphysema (percentage of pixels below −950 HU [%LAA–950]) and airway wall thickness (wall area percentage and the ratio of airway wall thickness to total diameter). Meanwhile, they completed the CAT and modified Medical Research Council questionnaire independently.


          Significantly higher CAT scores and CT measurements were found in COPD patients compared with normal control subjects ( P<0.05), and there was a tendency of higher CAT scores and CT measurements with increasing disease severity measured by GOLD staging system. Positive correlations were found between CAT scores and CT measurements ( P<0.01). Using multiple linear stepwise regression, CAT score =−46.38+0.778× (wall area percentage) +0.203× (%LAA–950) ( P<0.001). Meanwhile, CAT scores and CT measurements in COPD patients all positively correlated with the modified Medical Research Council grades and negatively correlated with FEV 1% ( P<0.01).


          CAT scores correlate well with the quantitative CT measurements in COPD patients, which may provide an imaging evidence that the structural changes of the lungs in this disease are associated with the health status measured by CAT.

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          Most cited references 24

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          Comparison of computed density and macroscopic morphometry in pulmonary emphysema.

          High-resolution computed tomography (HRCT) scans were obtained at 1 cm intervals in 63 subjects referred for surgical resection of a cancer or for transplantation to find out whether the relative area of lung occupied by attenuation values lower than a threshold would be a measurement of macroscopic emphysema. Using a semiautomatic procedure, the relative areas occupied by attenuation values lower than eight thresholds ranging from -900 to -970 HU were calculated on the set of scans obtained through the lobe or the lung to be resected. The extent of emphysema was quantified by a computer-assisted method on horizontal paper-mounted lung sections obtained every 1 to 2 cm. The only level for which no statistically significant difference was found between the HRCT and the morphometric data was -950 HU. To determine the number of scans sufficient for an accurate quantification, we recalculated the relative area occupied by attenuation values lower than -950 HU on progressively fewer numbers of scans and investigated the departure from the results obtained with 1 cm intervals. Because of wide variations in this departure from patient to patient, a standard cannot be recommended as the optimal distance between scans.
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            The COPD assessment test (CAT): response to pulmonary rehabilitation. A multicentre, prospective study.

            The COPD (chronic obstructive pulmonary disease) assessment test (CAT) is a recently introduced, simple to use patient-completed quality of life instrument that contains eight questions covering the impact of symptoms in COPD. It is not known how the CAT score performs in the context of clinical pulmonary rehabilitation (PR) programmes or what the minimum clinically important difference is. The introduction of the CAT score as an outcome measure was prospectively studied by PR programmes across London. It was used alongside other measures including the St George's Respiratory Questionnaire, the Chronic Respiratory Disease Questionnaire, the Clinical COPD Questionnaire, the Hospital Anxiety and Depression score, the Medical Research Council (MRC) dyspnoea score and a range of different walking tests. Patients completed a 5-point anchor question used to assess overall response to PR from 'I feel much better' to 'I feel much worse'. Data were available for 261 patients with COPD participating in seven programmes: mean (SD) age 69.0 (9.0) years, forced expiratory volume in 1 s (FEV(1)) 51.1 (18.7) % predicted, MRC score 3.2 (1.0). Mean change in CAT score after PR was 2.9 (5.6) points, improving by 3.8 (6.1) points in those scoring 'much better' (n=162), and by 1.3(4.5) in those who felt 'a little better' (n=88) (p=0.002). Only eight individuals reported no difference after PR and three reported feeling 'a little worse', so comparison with these smaller groups was not possible. The CAT score is simple to implement as an outcome measure, it improves in response to PR and can distinguish categories of response.
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              The prediction of small airway dimensions using computed tomography.

              Chronic obstructive pulmonary disease is characterized by destruction of the lung parenchyma and/or small airway narrowing. To determine whether the dimensions of relatively large airways assessed using computed tomography (CT) reflect small airway dimensions measured histologically, we assessed these variables in nonobstructed or mild to moderately obstructed patients having lobar resection for a peripheral tumor. For both CT and histology, the square root of the airway wall area (Aaw) was plotted versus lumen perimeter to estimate wall thickness. The wall area percentage was calculated as wall area/lumen area + wall area x 100. Although CT overestimated Aaw, the slopes of the relationships between the square root of Aaw and internal perimeter (Pi) measured with both techniques were related (CT slope = 0.2059 histology slope + 0.1701, R2 = 0.32, p < 0.01). The mean wall area percentage measured by CT for airways with a Pi of greater than 0.75 cm predicted the mean dimensions of the small airways with an internal diameter of 1.27 mm (R2 = 0.57, p < 0.01). We conclude that CT measurements of airways with a Pi of 0.75 cm or more could be used to estimate the dimensions of the small conducting airways, which are the site of airway obstruction in chronic obstructive pulmonary disease.

                Author and article information

                Int J Chron Obstruct Pulmon Dis
                Int J Chron Obstruct Pulmon Dis
                International Journal of COPD
                International Journal of Chronic Obstructive Pulmonary Disease
                Dove Medical Press
                05 March 2015
                : 10
                : 507-514
                Pulmonary Department, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People’s Republic of China
                Author notes
                Correspondence: Guang-He Fei, Pulmonary Department, First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui, People’s Republic of China, Tel +86 551 6292 2013, Fax +86 551 6363 5578, Email guanghefei@

                *These authors contributed equally to this work

                © 2015 Zhang et al. This work is published by Dove Medical Press Limited, and licensed under Creative Commons Attribution – Non Commercial (unported, v3.0) License

                The full terms of the License are available at Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

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