Lung function, smoking and survival in severe alpha 1-antitrypsin deficiency, PiZZ

Lung function, smoking, age and mortality data in 158 adult severe alpha₁-antitrypsin deficient, PiZZ individuals, followed from 1963 to 1982 were analyzed. Low initial FEV₁ value was significantly associated with increased mortality (p < 0.005). A 3 yr mortality rate of 40% was found in individuals whose initial FEV₁ values were less than 30% of that predicted. In contrast, the corresponding 3-yr mortality among those whose initial FEV₁ values were between 30 and 65% of that predicted was only 7%. Smokers were found to have significantly lower FEV₁ levels (p = 0.008) and higher mortality (p < 0.005) than non-smokers. The difference between current and ex-smokers in mortality and FEV₁ level were not statistically significant (p = 0.9 and p>0.25, respectively). Cross-sectional analysis of the initial FEV₁ values indicated a significant decline (p < 0.005) of FEV₁ with increasing age. This decline was greater among smokers than non-smokers. Longitudinal analysis of FEV₁ rates of decline in 80 cases with follow-up FEV₁ measurements failed to detect any significant differences between smokers and non-smokers, but was performed late in the disease process. The application of these results to the planning of studies on replacement therapy, smoking intervention strategy and longitudinal follow-up is discussed.