Clinical Practice Guideline Implementation for Alpha-1 Antitrypsin Deficiency Testing: Evaluation of an Innovative Method

Abstract

Purpose/Aims: The American Thoracic Society (ATS) published recommendations for alpha-1 antitrypsin deficiency (AATD) testing in 2003. This descriptive project evaluates the outcomes of ATS AATD guideline use in the setting of the pulmonary function testing (PFT) lab.The specific aims met by this descriptive project describe the prevalence of AATD cases and carriers in the sample, examine to what degree the established clinical guideline promoted accurate patient selection for the alpha-1 test in the sample, and aimed to determine whether alpha-1 antitrypsin blood levels are reduced in current smokers compared to former or never smokers.Background: Alpha-1 antitrypsin prevents lung tissue breakdown by attenuating excess elastase released from neutrophils during the inflammatory response. Smoking impairs alpha-1 antitrypsin protection at the site of lung inflammation promoting emphysema development. In the case of genetic mutation, protective alpha-1 antitrypsin levels are reduced, causing emphysema even in non-smokers. Significantly reduced protective levels of alpha-1 antitrypsin increase the odds for morbidity and early mortality from emphysema. The literature provides support for targeted testing in the population most affected.Sample/Methods: The sample population included adults 21 through 79 years completing pulmonary function testing over 18 months in a metropolitan pulmonary medicine practice and was retrospectively reviewed.Of the 521 in the sample, 190 were tested for AATD, and 24 were found to carry an abnormal genotype. However, using Table 11 from the ATS CPG failed to provide structured, consistent guidance in selecting patients for AATD testing. Still, the prevalence of the abnormal genotypes MS, MZ, SZ, and ZZ was increased in this pulmonary population compared to the published estimated prevalence for the general population.A structured decision-tree, developed from the original guideline for diagnostic testing, may provide superior guidance for AATD test patient selection in this setting. Increased case finding by targeted testing of patients in the setting of the pulmonary function lab can serve to integrate this clinical practice guideline in a consistent streamlined fashion.In this sample, no difference between AAT blood levels among ever, never, and current tobacco smokers was detected. A more powerful sample is needed.