The Veterans Administration Cooperative Study of Pulmonary Function. III. Mortality in Relation to Respiratory Function in Chronic Obstructive Pulmonary Disease

Abstract

Abstract A cooperative study of life expectancy in chronic obstructive pulmonary disease (COPD) has been conducted in fifteen Veterans Administration Hospitals that had previously contributed to the study of pulmonary function in normal men [9,10]. Between October 1957 and July 1960, 487 men were selected for study on the basis of characteristic clinical manifestations of COPD and the presence of residual volume: total lung capacity (RV:TLC) ratio of 35 per cent or greater, together with a total lung capacity (TLC) larger than 80 per cent of their predicted normal value. Upon entrance into the study, clinical information was obtained for each patient and all were studied by those pulmonary function tests previously standardized among the participating hospitals. These consisted of measurements of lung volume, maximal expiratory air flow rates and maximal voluntary ventilation. In addition, arterial blood-gas contents were measured by conventional methods. At four years after entrance into the study, the mortality rate for this group of patients was 53 per cent. An excellent correlation was found between life expectancy and the degree of physiologic disturbance at the time of first study. This was true for disturbances in ventilatory function as well as alterations in gas exchange. In addition, the previously reported unfavorable influence upon prognosis of an episode of right heart failure from cor pulmonale was confirmed. In contrast to previous studies, a correlation of the vital capacity, residual volume and residual volume to total lung capacity ratio and a lack of correlation of polycythemia with survival was found. Finally, it was observed that patients with COPD who reside at moderately elevated altitudes have a significantly higher mortality rate than those who live at sea level. This difference probably results from the higher incidence of cor pulmonale among the patients residing at high altitude.