High-resolution computed tomography scanning in alpha1-antitrypsin deficiency: relationship to lung function and health status.

The development of computed tomography (CT) has enabled emphysema to be assessed noninvasively. Objective quantification of lung density correlates well with lung function in patients with chronic obstructive pulmonary disease and has been shown to be a sensitive tool for monitoring disease progression. In order to determine the clinical impact of changes seen on high-resolution computed tomography (HRCT), the relationship between the objective quantification of emphysema on HRCT, lung function and health status in 111 patients with alpha1-antitrypsin deficiency was examined (PiZ). The degree of HRCT scan abnormality correlated well (p<0.001 for all comparisons) with forced expiratory volume in one second (r = -0.60- -0.75), specific airway conductance (r = -0.67-0.76), residual volume/total lung capacity (r = 0.46-0.58) and transfer factor of the lung for carbon monoxide (r = -0.64- -0.81). In addition, the CT scans correlated (p<0.001) with health status as assessed by the St. George's Respiratory Questionnaire (SGRQ total: r = -0.38-0.50) and the Short-Form health survey (e.g. physical functioning: r = -0.39-0.54). In summary, other workers have shown high-resolution computed tomography to be a sensitive indicator of disease progression. This study confirms the relationship between high-resolution computed tomography and lung physiology, and suggests the relationship is even stronger in patients with predominantly lower zone pan-lobular emphysema than in usual chronic obstructive pulmonary disease. High-resolution computed tomography also relates to patients disability and impairment as defined by health status questionnaires and, therefore, should be considered as an alternative outcome measure particularly in alpha1-antitrypsin deficiency.