The correlation between emphysema’s severity on the chest computed tomography and clinical characteristics, fev1, chest x - ray in patients with stable copd

Nội dung text: The correlation between emphysema’s severity on the chest computed tomography and clinical characteristics, fev1, chest x - ray in patients with stable copd

1. Journal of military pharmaco-medicine n 08-2017 THE CORRELATION BETWEEN EMPHYSEMA’S SEVERITY ON THE CHEST COMPUTED TOMOGRAPHY AND CLINICAL CHARACTERISTICS, FEV 1, 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, FEV 1 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 FEV 1 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 [9]. Unlike previous versions, GOLD 2017 Chronic obstructive pulmonary disease classifies the patients with the groups A - D, (COPD) is a disease characterized by that do not depend on results of lung incompletely reversible airway limitation. function [9]. That consequence results from the increase Computed topography (CT), especially in airway resistance due to small airway the HRCT and multislide computed obstruction and loss of lung elastic recoil topography is the most accurate imaging due to emphysema. The lung function method for detection and classification of testing only helps to confirm the airway emphysema’s severity. The way how to limitation, but not to identify the pathological identify and classify the emphysema’s changes as well as not to reflect all of severity on CT could be qualilative and clinical characteristics of the COPD patients 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
2. Journal of military pharmaco-medicine n 08-2017 identify the correlation with damaging of COPD test (ACT), classification COPD histology by emphysema. Applying imaging into groups A - D from GOLD 2107 [9]. techniques for phenotype of COPD - Lung function testing: Patients were classification is likely to help us to understand measured their lung function apart from more about the heterogeneity of COPD, exacerbation, by using KoKo - Spirometer to make a better prognosis and an appropriate (nSpire Health, USA). They were performed approach in treatment. In Vietnam, there spirometry before and 15 minutes after have been a few studies about imaging characteristics regarding chest of COPD bronchodilation test with salbutamol 400 µg patients and also have no consistent (ventolin) through spacer. The measurement conclusions about the correlation between techinique followed ATS/ERS standards the emphysema’s severity and ventilatory [5]. Diagnosis of COPD is confirmed when lung function [1, 2]. the ratio FEV 1/FVC < 0.7 after bronchodilation The aim of this study is: To identify the use. The severity of airway obstruction is correlation between the emphysema’s based on GOLD 2017, by the value of % severity classified by chest CT with FEV 1 predicted after bronchodilation [9]. clinical characteristics, FEV 1 and chest - Chest X-ray: All of the patients were X-ray of patients with stable COPD. performed frontal and lateral chest X-ray by the digital machine (Quantum, USA). SUBJECTS AND METHODS The results were interpreted as existing 1. Subjects. emphysema, no emphysema and The study was carried out on 112 patients unidentifiable. The analysis was taken with stable COPD, managed in the from the cases with emphysema or not. Respiratory Consultation Unit of Cantho The unclear cases were classified in the Central Hospital. The criteria of COPD unidentified group. The criteria for emphysema diagnosis are based on GOLD 2017 should meet at least 2 among 4 points guidelines [9]. The patients with diagnosis of asthma, tuberculosis, lung tumor, below [8]: On the frontal chest X-ray: bronchiectasis, previous chest operation, diaphragm is flat and low: the distance pneumothorax, without permission to from the highest point of diaphragm perform spirometry, without agreement to outline to the line between cardio phrenic participate in the study were excluded. angle and costo phrenic angle < 1.5 cm; 2. Method. heterogious lucency in two lung fields. On the lateral chest X-ray: increased retrosternal - Study design: Descriptive cross-sectional space: measurement from the sternum to study. the anterior margin of ascending aorta - Variables selected such as age, ≥ 2.5 cm; flattening of diaphragm: sterno gender, smoking status (packs-year), 0 number of exacerbation during the last 12 phrenic angle ≥ 90 . previous months, BMI, cough, expectoration, - Chest HRCT procedure: GE 64 slices chronic dyspnea on exertion, degree of scanner machine (USA) was used with dyspnea based on MRC, scales, assessment the thickness of slide about 0.625 mm, 188
3. Journal of military pharmaco-medicine n 08-2017 permeability: 120 kV, mA = 600. Patients threshold - 950 HU Hounsfield unit (%LAA were taken the chest HRCT in inspiration ≤ 950 HU) to identity the severity of without contrast. The percentage of low emphysema based on Rutten EP criteria attenuation area that was less than the [7]. RESULTS 1. Patient’s characteristics. There were 112 patients recruited for the study. Population characteristics (gender, age) and clinical manifestations were presented in the table 1. Table 1: Patients’s characteristics. Patient’s characteristics Results (n, %) Gender (n, %): Male 110 (98,2) Female 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 5 (4,5) Chronic dyspnea 15 (13,4) Cough, expectoration and chronic dyspnea 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 14 (12,5) Group B 25 (22,3) Group C 26 (23,2) Group D 47 (43,0) Severity of airway limitation (n, %) GOLD 1 14 (12,5) GOLD 2 57 (50,9) GOLD 3 35 (31,2) GOLD 4 6 (5,4) Emphesema’s severity on the chest CT (%LAA ≤ 950 HU) (n, %) No emphesema 48 (42,9) Minor 60 (53,6) Moderate 4 (3,6) Severe 0 (Abbreviations: SD: Standard deviation; BMI: Body mass index); MRC: Medical research council; CAT: COPD assssment test; %LAA: % low attenuation area) 189
4. Journal of military pharmaco-medicine n 08-2017 2. 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 2. Table 2: The correlation between %LAA ≤ 950 HU with clinical respiratory signs, multiexacerbation characteristics of MRC scales, CAT scores, A - D groups classification. Compared Clinical Multiexacerbation MRC CAT BMI A - D variables respiratory signs scales score groups %LAA ≤ 950 HU PCC -0,01 0,073 0,389 0,268 -0.279 0,019 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). 3. 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 3. Table 3: Results from evaluation of existing emphysema in conventional chest X-ray, %LAA ≤ 950 HU and their correlation. Results Correlation Existing emphesema; Emphysema: 14 (13.5%) n (%) PCC: 0.22 Not emphysema: 43 (38.4%) 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
5. Journal of military pharmaco-medicine n 08-2017 4. Correlation between emphysema pack-years. The patients had the mean evaluated on chest X-ray, percentage BMI 20.3 (3.3), that was underweight. The of low attenuation area on chest CT majority of patients (82.1%) had both (%LAA) with value of %FEV 1 predicted symptoms as cough, expectoration and after bronchodilaton. chronic dyspnea. The classification COPD Table 4: Correlation between emphysema into groups A - D based on GOLD guidelines evaluated on chest Xray, %LAA ≤ 950 HU was applied and revealed that COPD and FEV 1. patients in group D had the highest percentage (43%), followed by group B FEV 1 and C (22.3% and 23.2%, respectively), Conventional chest PCC (r) -0.043 finally group A (12.5%). The number of X ray p value 0.650 patients with high risks (multiple exacerbation) %LAA ≤ 950 HU PCC (r) -0.278 (**) and more symptoms outweight those with p value 0.003 low risks and less symptoms. The patients (**: Significant correlation if < 0.01) with the severity of airway limitation GOLD 2 and GOLD 3 were predominant (50.9% and 30.2%, respectively), GOLD 1 and GOLD 4 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. Graph 1: Correlation between the severity The role of quantitative CT was more of emphysema (%LAA ≤ 950HU) and and more confirmed in evaluation of the %FEV predicted after bronchodilation. 1 pathological changes in COPD. Identifying The value of %LAA ≤ 950 HU and FEV 1 the severity of emphysema on chest CT were inversely proportional with p < 0.01. based on the percentage of low attenuation area less than the threshold - 950 Houndsfield DISCUSSION unit (%LAA ≤ 950 HU), is correlated with histological change. In this study, patients with In this study, males were predominant minor and moderate emphysema were with 98.2%, females only 1.8%. The average 53.6% and 3.6%, respectively, and no age was 69.5 (8.9) and the past history case with severe emphysema. Pham Kim smoking was on average about 33.4 (10.7) Lien et al had shown the same results [2]. 191
6. Journal of military pharmaco-medicine n 08-2017 The severity of emphysema on the after bronchodilation (p < 0.01), and compatible chest CT (%LAA ≤ 950 HU) did not correlate with the study of Dang Vinh Hiep et al [1], with clinical respiratory symptoms, multiple Gupta P [3] and Yan Zhang [10]. exacerbations and classification of COPD patients in groups A - D based on GOLD. CONCLUSION On the contrary, the severity of emphysema The chest CT has the key role to evaluate was directly correlation to MRC scales specific damage and lesions of COPD. (PCC = 0.389, p = 0.0001) and to CAT The severity of emphysema based on the (PCC = 0.268, p = 0.004), as well as with percentage of low attenuation area ≤ 950 HU BMI (PCC = -0.279, p = 0.003). The results on the chest CT is directly correalation with of this study were similar to those of Yan MRC scales and CAT score, inversely Zhang [10]. Patients COPD with predominant correalation with value of post-bronchodilation emphysema phenotype were recognized FEV 1. Results from evaluation of existing that they are thinner, more dyspneique and emphysema by conventional chest X-ray less well-being. correlated with %LAA ≤ 950 HU. Chest X-ray Although chest CT could make an and chest CT could have the significant accurate diagnosis of emphysema, it does role to identify the emphysema phenotype not still become the routine method due to in patients with COPD. That is likely to its high cost. In the contrary, conventional contribute to approach and treat effectively chest X-ray could be used routinely for for patients with COPD. COPD patients, but its accuracy in emphysema diagnosis is not consistent in REFERENCES other studies. This study had shown that, 1. Đặng V ĩnh Hi ệp, Ph ạm Ng ọc Hoa . Đánh identifying emphysema on chest X-ray and giá s ự t ươ ng quan gi ữa CT định l ượng và %LAA ≤ 950 HU on the chest CT were ch ức n ăng hô h ấp trong b ệnh ph ổi t ắc ngh ẽn correlated (p < 0.05). In the two recent mạn tính. Lu ận v ăn Chuyên khoa C ấp II. studies, chest X-ray had demonstrated its Tr ường Đại h ọc Y D ược TP. H ồ Chí Minh. 2008. value in emphysema diagnosis with sensitivity and specitivity more than 80% [4, 6]. 2. Ph ạm Kim Liên, D ươ ng H ồng Thái, Đỗ Quy ết. Nghiên c ứu đặc điểm hình ảnh khí COPD is characterized by the airway ph ế th ũng và m ối liên quan v ới tình tr ạng gi ảm limitation with incomplete reversibility kh ối c ơ th ể ở BN m ắc b ệnh ph ổi t ắc ngh ẽn which results from the changes in airways mạn tính. Tạp chí Y h ọc th ực hành. 2011, 766, and parenchymal lungs. Emphysema status tr.119-123. has led to lose elastic lung recoil causing 3. Gupta P, Yadav R, Verma M et al. the airway limitation in COPD. The study Correlation between high-resolution computed results had shown that emphysema’s tomography features and patients' characteristics severity on the chest CT is insversly in chronic obstructive pulmonary disease. Ann proportional to %FEV 1 predicted value Thorac Med. 2008, 3 (3), pp.87-93. 192
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