Letters to the Editor
Managing chronic obstructive pulmonary disease
- Michael A Kennedy, Michael Abramson, Nicholas Glasgow, Christine McDonald
- Aust Prescr 2007;30:64-7
- 1 December 2007
- DOI: 10.18773/austprescr.2007.082
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Editor, – I wonder why alpha-1 antitrypsin deficiency was not mentioned in the article on 'Managing chronic obstructive pulmonary disease' (Aust Prescr 2007;30:59-63). There is worldwide evidence that this genetic problem is much more common than it was thought in the past. In fact the World Health Organization advises that everybody with chronic obstructive pulmonary disease should be tested for alpha-1 antitrypsin deficiency, especially since there is treatment for it, though no cure.
Michael A Kennedy
General practitioner, retired
Professor Michael Abramson, Associate Professor Christine McDonald and Professor Nicholas Glasgow, authors of the article, comment:
We thank Dr Kennedy for drawing attention to the role of alpha-1 antitrypsin deficiency in chronic obstructive pulmonary disease (COPD). This genetic disorder is evidence for the elastase-antielastase hypothesis of emphysema. The prevalence of severe homozygous (ZZ) alpha-1 antitrypsin deficiency has been estimated at around 1/4,727 in European populations.1 Although 75-85% of such individuals will develop emphysema, tobacco smoking is still the most important risk factor for COPD even in this group. Targeted screening suggests 1-4.5% of patients with COPD have underlying severe alpha-1 antitrypsin deficiency.2 The index of suspicion should be high in younger patients with predominantly basal disease and a family history. The diagnosis can be made by measuring serum levels of alpha-1 trypsin. If they are reduced, genotyping should be performed. Whether people who are heterozygous (MZ, MS) are also at an increased risk of COPD remains controversial.
Although replacement therapy is available, trials conducted to date have been underpowered to confirm beneficial effects on the rate of decline in lung function or on survival. One placebo-controlled randomised trial suggested some reduction in the loss of lung tissue as assessed by CT scan.3 Therapy involves intravenous administration of alpha-1 trypsin concentrate purified by fractionation of normal human plasma or recombinant alpha-1 trypsin. These products can restore alpha-1 trypsin levels above the protective threshold for some weeks. Replacement therapy is available through the Special Access Scheme. A national patient support group can be contacted at http://health.groups.yahoo.com/group/Alpha1-ANZ.
General practitioner, retired, Vaucluse, NSW
Department of Epidemiology and Preventive Medicine, Monash University, Melbourne
Australian Primary Health Care Research Institute, Canberra
Department of Respiratory and Sleep Medicine, Austin Health, Melbourne