Background: The aim of this study was to uniquely describe CT scan appearance, densitometry, and health status in subjects with protease inhibitor SZ phenotype (PiSZ) alpha(1)-antitrypsin deficiency (AATD) compared with matched subjects with protease inhibitor ZZ phenotype (PiZZ).
Methods: The presence and type of emphysema seen on CT scan, upper and lower zone densitometry, health status, physiology, and symptoms were compared for 126 subjects (63 with PiSZ, 63 with PiZZ) from the UK AATD registry, matched for age, gender, and smoking status. Similar analyses were performed for lung index and nonindex subgroups.
Results: A lower proportion of PiSZ index (46%) and non-PiSZ index (15%) subgroup case patients showed visible emphysema on CT scans compared with matched PiZZ index (91%; p < 0.001) and non-PiZZ index (61%; p = 0.011) case patients. Sixty-five percent of subjects with PiSZ and 74% with PiZZ had panacinar emphysema (p = 0.54); however, a greater proportion (p = 0.005) of the PiSZ group (39%) had upper zone-predominant emphysema compared with the PiZZ group (12%). Densitometric analysis revealed less extensive emphysema in the lower zones, but not the upper zones, of subjects with PiSZ than those with PiZZ. When subjects were matched for ascertainment method, health status was similar between the two phenotypes, despite the differences in CT scan and densitometry findings, and more abnormal respiratory physiology test results in subjects with PiZZ.
Conclusions: Subjects with PiSZ showed less emphysema on CT scans, more apical predominance, less abnormal respiratory physiology test results, but similar health status impairment compared with matched subjects with PiZZ.