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SELECTED ARTICLES FROM THE RECENT LITERATURE 2007
November 2, 2007
We will be seeing more adult cystic fibrosis patients, some of whom will have not been diagnosed
Summary
In the last 40 years, the survival time of cystic fibrosis patients has increased dramatically. The current median survival in cystic fibrosis is 36.9 years. Thus, the number of adults with cystic fibrosis has increased tremendously in this time period. Last year, there were 10 individuals older than 70 years noted in the United States Cystic Foundation National Data Registry. About 5% of individuals with cystic fibrosis are diagnosed after age 16. A number of older patients oftentimes have less gastrointestinal symptoms and can present with only chronic sinopulmonary disease as manifested by chronic cough and sputum production. These patients have chronic sinusitis and chronic bronchiectasis, and may resemble patients with common variable immunodeficiency. Thus it would not be unexpected that allergists will see older patients with cystic fibrosis who have not been previously diagnosed. It is therefore important to keep a high index of suspicion.
The test of choice is a sweat test. Genotyping to look for the presence of two cystic fibrosis mutations is the second option. However, the author states that the sensitivity of genotyping is dependent on the number of mutations tested for, and the ethnic background of the individual being tested. There are approximately 1500 different mutations to date. Cost considerations, and the difficulty in testing for all mutations, thus limit genotyping. However, in patients with equivocal sweat test results, genotyping can be very valuable.
Editor's Comments
Treatment options for cystic fibrosis patients have improved, thus extending the life of such patients. We also recognize that many patients are not diagnosed until late adolescence. This article is a valuable resource to the reader in understanding the pathophysiology, clinical presentation, and appropriate therapy for the adult cystic fibrosis patient. Allergists-immunologists need to be familiar with these issues since patients are often referred to us with similar airway complaints.
Reference
Boyle MP. Adult cystic fibrosis. In: JAMA, October 2007; 298(15):1787-1793.
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