Correlation study of semi-quantitative CT emphysema score with the BODE index in COPD patients

Background: Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation due to airway narrowing and loss of elastic recoil. Emphysema is the hallmark of elasticity loss and can be assessed by CT scan by measuring low attenuation areas (LAA). The BODE staging system, including FEV1 and other variables, helps to predict mortality and hospitalization for COPD. Aim: To assess any relationship between BODE index and CT extension of emphysema in mild-to-severe COPD patients. Patients and study design: Thirty-three out of 48 enrolled out-patients were included in the study (M/F: 24/9, mean age±SD: 67±8.9 yrs; smoking history: 34±19 pack/yrs). BODE index and semi-quantitative CT scoring of emphysema were calculated for each patient within two weeks from enrolment. Results: The mean BODE index and CT emphysema score were 4.3±3.2 and 1±1.2, respectively. No emphysema was recorded in 16 (48%) patients; the emphysema score was 1 (less than 25% of LAA) in seven cases, 2 (between 25 and 75%) in 6 cases and 3 (more than 75%) in 3 patients. Severe emphysema (score: 4) was reported in one patient. We found no correlation between the emphysema score and the BODE index (p= 0.348; r=0.168). Similarly, no correlation was found with FEV1, the level of dyspnoea (MMRC score) and the 6-minute walking distance (m). However, a weak inverse correlation was found with the body mass index (p 0.038; r -0.362). Conclusions: Our preliminary results suggest that no correlation exists between BODE index and semi-quantitative CT emphysema scoring. Further efforts better assessing emphysema and other COPD-related pathological abnormalities, i.e. airway remodelling, are needed in larger samples siz