Objectives: To identify the correlation between the severity of emphysema on chest CT with clinical characteristics, FEV1 and chest X-ray in stable COPD patients. Subjects: 112 COPD patients in stable stage, managed at the Respiratory Consultation Unit of Cantho Central Hospital.
Journal of military pharmaco-medicine n08-2017 THE CORRELATION BETWEEN EMPHYSEMA’S SEVERITY ON THE CHEST COMPUTED TOMOGRAPHY AND CLINICAL CHARACTERISTICS, FEV1, CHEST X-RAY IN PATIENTS WITH STABLE COPD Cao Thi My Thuy*; Dong Khac Hung**; Nguyen Van Thanh* SUMMARY Objectives: To identify the correlation between the severity of emphysema on chest CT with clinical characteristics, FEV1 and chest X-ray in stable COPD patients Subjects: 112 COPD patients in stable stage, managed at the Respiratory Consultation Unit of Cantho Central Hospital Study design: Descriptive cross-sectional study based on the percentage of low attenuation area less than the threshold - 950 Hounsfield Unit (%LAA ≤ 950 HU) on high resolution computed topography (HRCT) in order to identify the severity of emphysema The clinical characteristics were selected as well as frontal and lateral chest X-ray, lung function test, classification COPD into groups A - D from GOLD 2017 Results: The severity of emphysema on chest CT is direct correlation with MRC scales (PCC = 0.389, p = 0.0001) and CAT (PCC = 0.268, p = 0.004), but inversely correlation to the value of FEV1 after bronchodilation (PCC= -0.278, p = 0.003) The results from emphysema evaluated on chest X-ray and %LAA ≤ 950 HU were correlated (PCC: 0.22, p: 0.018) Conclusions: The severity of emphysema leads to cause the airway limitation in COPD Chest X-ray has still the role for emphysema’s diagnosis The severity of emphysema correlates with dyspnea degrees and poor health status * Keywords: Stable chronic obstructive pulmonary disease; Emphysema; Chest CT; Clinical characteristics INTRODUCTION Chronic obstructive pulmonary disease (COPD) is a disease characterized by incompletely reversible airway limitation That consequence results from the increase in airway resistance due to small airway obstruction and loss of lung elastic recoil due to emphysema The lung function testing only helps to confirm the airway limitation, but not to identify the pathological changes as well as not to reflect all of clinical characteristics of the COPD patients [9] Unlike previous versions, GOLD 2017 classifies the patients with the groups A - D, that not depend on results of lung function [9] Computed topography (CT), especially the HRCT and multislide computed topography is the most accurate imaging method for detection and classification of emphysema’s severity The way how to identify and classify the emphysema’s severity on CT could be qualilative and quantitative The quantitative method could * Cantho Central Hospital ** Vietnam Military Medical University Corresponding author: Cao Thi My Thuy (bscaothimythuy@gmail.com) Date received: 20/08/2017 Date accepted: 28/09/2017 187 Journal of military pharmaco-medicine n08-2017 identify the correlation with damaging histology by emphysema Applying imaging techniques for phenotype of COPD classification is likely to help us to understand more about the heterogeneity of COPD, to make a better prognosis and an appropriate approach in treatment In Vietnam, there have been a few studies about imaging characteristics regarding chest of COPD patients and also have no consistent conclusions about the correlation between the emphysema’s severity and ventilatory lung function [1, 2] The aim of this study is: To identify the correlation between the emphysema’s severity classified by chest CT with clinical characteristics, FEV1 and chest X-ray of patients with stable COPD SUBJECTS AND METHODS Subjects The study was carried out on 112 patients with stable COPD, managed in the Respiratory Consultation Unit of Cantho Central Hospital The criteria of COPD diagnosis are based on GOLD 2017 guidelines [9] The patients with diagnosis of asthma, tuberculosis, lung tumor, bronchiectasis, previous chest operation, pneumothorax, without permission to perform spirometry, without agreement to participate in the study were excluded Method - Study design: Descriptive cross-sectional study - Variables selected such as age, gender, smoking status (packs-year), number of exacerbation during the last 12 previous months, BMI, cough, expectoration, chronic dyspnea on exertion, degree of dyspnea based on MRC, scales, assessment 188 of COPD test (ACT), classification COPD into groups A - D from GOLD 2107 [9] - Lung function testing: Patients were measured their lung function apart from exacerbation, by using KoKo - Spirometer (nSpire Health, USA) They were performed spirometry before and 15 minutes after bronchodilation test with salbutamol 400 µg (ventolin) through spacer The measurement techinique followed ATS/ERS standards [5] Diagnosis of COPD is confirmed when the ratio FEV1/FVC < 0.7 after bronchodilation use The severity of airway obstruction is based on GOLD 2017, by the value of % FEV1 predicted after bronchodilation [9] - Chest X-ray: All of the patients were performed frontal and lateral chest X-ray by the digital machine (Quantum, USA) The results were interpreted as existing emphysema, no emphysema and unidentifiable The analysis was taken from the cases with emphysema or not The unclear cases were classified in the unidentified group The criteria for emphysema should meet at least among points below [8]: On the frontal chest X-ray: diaphragm is flat and low: the distance from the highest point of diaphragm outline to the line between cardio phrenic angle and costo phrenic angle < 1.5 cm; heterogious lucency in two lung fields On the lateral chest X-ray: increased retrosternal space: measurement from the sternum to the anterior margin of ascending aorta ≥ 2.5 cm; flattening of diaphragm: sterno phrenic angle ≥ 900 - Chest HRCT procedure: GE 64 slices scanner machine (USA) was used with the thickness of slide about 0.625 mm, Journal of military pharmaco-medicine n08-2017 permeability: 120 kV, mA = 600 Patients were taken the chest HRCT in inspiration without contrast The percentage of low attenuation area that was less than the threshold - 950 HU Hounsfield unit (%LAA ≤ 950 HU) to identity the severity of emphysema based on Rutten EP criteria [7] RESULTS Patient’s characteristics There were 112 patients recruited for the study Population characteristics (gender, age) and clinical manifestations were presented in the table Table 1: Patients’s characteristics Patient’s characteristics Results (n, %) Gender (n, %): Male Female 110 (98,2) (1,8) Age (year), mean (SD) 69,5 (8,9) Smoking status: current or ex-smoker: package - year, mean (SD) 33,4 (10,7) BMI, mean (SD) 20,3 (3,3) Respiratory symptoms (n, %) Cough and/or chronic expectoration Chronic dyspnea Cough, expectoration and chronic dyspnea (4,5) 15 (13,4) 92 (82,1) Numbers of exacerbation in the previous 12 months, mean (SD) 1,73 (0,85) MRC, mean (SD) 1,88 (0,93) CAT, mean (SD) 14,23 (6,26) Classification GOLD into groups (A, B, C, D) (n, %) Group A Group B Group C Group D 14 (12,5) 25 (22,3) 26 (23,2) 47 (43,0) Severity of airway limitation (n, %) GOLD GOLD GOLD GOLD 14 (12,5) 57 (50,9) 35 (31,2) (5,4) Emphesema’s severity on the chest CT (%LAA ≤ 950 HU) (n, %) No emphesema Minor Moderate Severe 48 (42,9) 60 (53,6) (3,6) (Abbreviations: SD: Standard deviation; BMI: Body mass index); MRC: Medical research council; CAT: COPD assssment test; %LAA: % low attenuation area) 189 Journal of military pharmaco-medicine n08-2017 Correlation between %LAA ≤ 950 HU and respiratory symptoms, multiple exacerbation, BMI, MRC scales, CAT score and classification groups A - D The results from analyzing the correlation between the severity of emphysema and clinical respiratory symptoms, multiple exacerbation, BMI, MRC scales, CAT score, classification groups A - D had shown in table Table 2: The correlation between %LAA ≤ 950 HU with clinical respiratory signs, multiexacerbation characteristics of MRC scales, CAT scores, A - D groups classification Compared variables Clinical respiratory signs Multiexacerbation MRC scales CAT score BMI A-D groups -0,01 0,073 0,389 0,268 -0.279 0,019 %LAA ≤ 950 HU PCC p value 0.93 (*) 0.44 0.0001 (*) 0.004 (*) 0.003 p = 0.84 (*: significant correlation if < 0.01) The value %LAA ≤ 950 HU has the direct correlation with MRC scale and CAT, but inverse correlation with BMI (p < 0.01) Results of emphysema in chest X-ray, %LAA ≤ 950 HU and their correlation Results considered if there was an emphysema or not in conventional chest X-ray and the percentage of low attennuation area in chest CT (%LAA ≤ 950 HU) were presented in table Table 3: Results from evaluation of existing emphysema in conventional chest X-ray, %LAA ≤ 950 HU and their correlation Results Existing emphesema; Emphysema: 14 (13.5%) n (%) Not emphysema: 43 (38.4%) Correlation PCC: 0.22 p: 0.018 (*) Unidentifiable 55 (49.1%) %LAA ≤ 950 HU Mean (SD): 9,7 (8.3) Minimal value: 0.1 Maximal value: 42.4 (* p < 0.05) The result of analyzing this correlation is statistically significant with p < 0.05 190 Journal of military pharmaco-medicine n08-2017 Correlation between emphysema evaluated on chest X-ray, percentage of low attenuation area on chest CT (%LAA) with value of %FEV1 predicted after bronchodilaton Table 4: Correlation between emphysema evaluated on chest Xray, %LAA ≤ 950 HU and FEV1 FEV1 Conventional chest X ray PCC (r) -0.043 p value 0.650 %LAA ≤ 950 HU PCC (r) p value -0.278(**) 0.003 (**: Significant correlation if < 0.01) Graph 1: Correlation between the severity of emphysema (%LAA ≤ 950HU) and %FEV1 predicted after bronchodilation The value of %LAA ≤ 950 HU and FEV1 were inversely proportional with p < 0.01 DISCUSSION In this study, males were predominant with 98.2%, females only 1.8% The average age was 69.5 (8.9) and the past history smoking was on average about 33.4 (10.7) pack-years The patients had the mean BMI 20.3 (3.3), that was underweight The majority of patients (82.1%) had both symptoms as cough, expectoration and chronic dyspnea The classification COPD into groups A - D based on GOLD guidelines was applied and revealed that COPD patients in group D had the highest percentage (43%), followed by group B and C (22.3% and 23.2%, respectively), finally group A (12.5%) The number of patients with high risks (multiple exacerbation) and more symptoms outweight those with low risks and less symptoms The patients with the severity of airway limitation GOLD and GOLD were predominant (50.9% and 30.2%, respectively), GOLD and GOLD with 12.5% and 5.4%, respectively The parameters of patient’s characteristics are similar to those of Pham Kim Lien et al’s study [2] The difference about age, clinical manifestations and the severity of airways were compatible with the smoking habit as men smoke more than women, and compatible with natural change of diseases and the needs for healthcare with COPD patients The role of quantitative CT was more and more confirmed in evaluation of the pathological changes in COPD Identifying the severity of emphysema on chest CT based on the percentage of low attenuation area less than the threshold - 950 Houndsfield unit (%LAA ≤ 950 HU), is correlated with histological change In this study, patients with minor and moderate emphysema were 53.6% and 3.6%, respectively, and no case with severe emphysema Pham Kim Lien et al had shown the same results [2] 191 Journal of military pharmaco-medicine n08-2017 The severity of emphysema on the chest CT (%LAA ≤ 950 HU) did not correlate with clinical respiratory symptoms, multiple exacerbations and classification of COPD patients in groups A - D based on GOLD On the contrary, the severity of emphysema was directly correlation to MRC scales (PCC = 0.389, p = 0.0001) and to CAT (PCC = 0.268, p = 0.004), as well as with BMI (PCC = -0.279, p = 0.003) The results of this study were similar to those of Yan Zhang [10] Patients COPD with predominant emphysema phenotype were recognized that they are thinner, more dyspneique and less well-being Although chest CT could make an accurate diagnosis of emphysema, it does not still become the routine method due to its high cost In the contrary, conventional chest X-ray could be used routinely for COPD patients, but its accuracy in emphysema diagnosis is not consistent in other studies This study had shown that, identifying emphysema on chest X-ray and %LAA ≤ 950 HU on the chest CT were correlated (p < 0.05) In the two recent studies, chest X-ray had demonstrated its value in emphysema diagnosis with sensitivity and specitivity more than 80% [4, 6] COPD is characterized by the airway limitation with incomplete reversibility which results from the changes in airways and parenchymal lungs Emphysema status has led to lose elastic lung recoil causing the airway limitation in COPD The study results had shown that emphysema’s severity on the chest CT is insversly proportional to %FEV1 predicted value 192 after bronchodilation (p < 0.01), and compatible with the study of Dang Vinh Hiep et al [1], Gupta P [3] and Yan Zhang [10] CONCLUSION The chest CT has the key role to evaluate specific damage and lesions of COPD The severity of emphysema based on the percentage of low attenuation area ≤ 950 HU on the chest CT is directly correalation with MRC scales and CAT score, inversely correalation with value of post-bronchodilation FEV1 Results from evaluation of existing emphysema by conventional chest X-ray correlated with %LAA ≤ 950 HU Chest X-ray and chest CT could have the significant role to identify the emphysema phenotype in patients with COPD That is likely to contribute to approach and treat effectively for patients with COPD REFERENCES Đặng Vĩnh Hiệp, Phạm Ngọc Hoa Đánh giá tương quan CT định lượng chức hô hấp bệnh phổi tắc nghẽn mạn tính Luận văn Chuyên khoa Cấp II Trường Đại học Y Dược TP Hồ Chí Minh 2008 Phạm Kim Liên, Dương Hồng Thái, Đỗ Quyết Nghiên cứu đặc điểm hình ảnh khí phế thũng mối liên quan với tình trạng giảm khối thể BN mắc bệnh phổi tắc nghẽn mạn tính Tạp chí Y học thực hành 2011, 766, tr.119-123 Gupta P, Yadav R, Verma M et al Correlation between high-resolution computed tomography features and patients' characteristics in chronic obstructive pulmonary disease Ann Thorac Med 2008, (3), pp.87-93 Journal of military pharmaco-medicine n08-2017 Hassan W.A, Abo-Elhamd E Emphysema versus chronic bronchitis in COPD: Clinical and radiologic characteristics Open Journal of Radiology 2014, 4, pp.155-162 Miller M.R, Hankinson J, Brusasco V, Burgos F et al Series ‘ATS/ERS task force: Standardization of lung function testing Standardisation of spirometry Eur Respir J 2005, 26, pp.319-338 Miniati M, Monti, Stolk J et al Value of chest radiography in phenotyping chronic obstructive pulmonary disease Eur Respir J 2008, 31, pp.509-514 Rutten E.P, Grydeland T.B, Pillai S.G et al Quantitative CT: associations between emphysema, airway wall thickness and body composition in COPD Pulmonary Medicine 2011, p.6 Sutinen S, Christoforidis A.J, Klugh G.A, Pratt P.C Roentgenologic criteria for the recognition of nonsymptomatic pulmonary emphysema Correlation between roentgenologic findings and pulmonary pathology Am Rev Respir Dis 1965, 91, pp.69-76 The global stragtey for the diagnosis, management, and prevention of chronic obstructive pulmonary disease (GOLD) 2017 available at: www.goldcopd.com 10 Yan Zhang, You-Hui Tu, Guang-He Fei The COPD assessment test correlates well with the computed tomography measurements in COPD patients in China Int J Chron Obstruct Pulmon Dis 2015, 10, pp.507-514 193 ... have no consistent conclusions about the correlation between the emphysema’s severity and ventilatory lung function [1, 2] The aim of this study is: To identify the correlation between the emphysema’s. .. severity classified by chest CT with clinical characteristics, FEV1 and chest X-ray of patients with stable COPD SUBJECTS AND METHODS Subjects The study was carried out on 112 patients with stable. .. HU and their correlation Results considered if there was an emphysema or not in conventional chest X-ray and the percentage of low attennuation area in chest CT (%LAA ≤ 950 HU) were presented in