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Canadian Respiratory Journal
Volume 19, Issue 2, Pages 109-116
Special Article

Alpha-1 Antitrypsin Deficiency Targeted Testing and Augmentation Therapy: A Canadian Thoracic Society Clinical Practice Guideline

DD Marciniuk,1 P Hernandez,2 M Balter,3 J Bourbeau,4 KR Chapman,4 GT Ford,5 JL Lauzon,5 F Maltais,6 DE O’Donnell,7 D Goodridge,1 C Strange,8 AJ Cave,9 K Curren,10 S Muthuri,10 and Canadian Thoracic Society COPD Clinical Assembly Alpha-1 Antitrypsin Deficiency Expert Working Group

1University of Saskatchewan, Saskatoon, Saskatchewan, Canada
2Dalhousie University, Halifax, Nova Scotia, Canada
3University of Toronto, Toronto, Ontario, Canada
4McGill University, Montreal, Quebec, Canada
5University of Calgary, Calgary, Alberta, Canada
6Laval University, Laval, Quebec, Canada
7Queen’s University, Kingston, Ontario, Canada
8Medical University of South Carolina, Charleston, South Carolina, USA
9University of Alberta, Edmonton, Alberta, Canada
10Canadian Thoracic Society, Ottawa, Ontario, Canada

Copyright © 2012 Canadian Thoracic Society. This open-access article is distributed under the terms of the Creative Commons Attribution Non-Commercial License (CC BY-NC) (, which permits reuse, distribution and reproduction of the article, provided that the original work is properly cited and the reuse is restricted to noncommercial purposes.


Alpha-1 antitrypsin (A1AT) functions primarily to inhibit neutrophil elastase, and deficiency predisposes individuals to the development of chronic obstructive pulmonary disease (COPD). Severe A1AT deficiency occurs in one in 5000 to one in 5500 of the North American population. While the exact prevalence of A1AT deficiency in patients with diagnosed COPD is not known, results from small studies provide estimates of 1% to 5%. The present document updates a previous Canadian Thoracic Society position statement from 2001, and was initiated because of lack of consensus and understanding of appropriate patients suitable for targeted testing for A1AT deficiency, and for the use of A1AT augmentation therapy. Using revised guideline development methodology, the present clinical practice guideline document systematically reviews the published literature and provides an evidence-based update. The evidence supports the practice that targeted testing for A1AT deficiency be considered in individuals with COPD diagnosed before 65 years of age or with a smoking history of <20 pack years. The evidence also supports consideration of A1AT augmentation therapy in nonsmoking or exsmoking patients with COPD (forced expiratory volume in 1 s of 25% to 80% predicted) attributable to emphysema and documented A1AT deficiency (level ≤11 μmol/L) who are receiving optimal pharmacological and nonpharmacological therapies (including comprehensive case management and pulmonary rehabilitation) because of benefits in computed tomography scan lung density and mortality.