Reduction of lymphocyte at early stage elevates severity and death risk of COVID-19 patients: a hospital-based case-cohort study

Jun Fei; Lin Fu; Ying Li; Hui-Xian Xiang; Ying Xiang; Meng-Die Li; Fang-Fang Liu; De-xiang Xu; Hui Zhao

ground-glass opacities, consolidation, traction bronchiectasis, bronchial wall thickening, reticulation, subpleural bands, vascular enlargement and lesion distribution. The detailed CT image characteristics of 200 COVID-19 patients were described in other work (8) . On the image scans, the pulmonary tissues were divided into two single lungs (left and right lung) and three zones (upper, middle, and lower zones of lung in the bilateral lungs). These areas of the lung were defined as the "upper zones" above the level of the carina; the "middle zones" between the level of the carina and the level of the inferior pulmonary veins; and the "lower zones" below the level of the inferior pulmonary veins. The CT score was determined by visually estimating the extent of disease in each zone. The severity scores were evaluated according to the percentage of lung parenchyma in each zone that showed evidence of each recorded abnormality: (1) no injury; (2) 1 point, involvement of less than 25% of the image; (3) 2 ponits, 25% to 50%; (4) 3 points, 50% to 75%; (5) 4 ponits, more than 75%. A total severity scores (between 0 and 24) for each lung were generated via adding all the partial areas. The total scores represented the damage area for each lung tissue (9) .