Physicians should maintain a high degree of suspicion and carefully examine any patient who has had two or more relatives with pulmonary fibrosis since genetic susceptibility plays a significant role in the development of this fatal disease, especially among smokers. This warning to help identify early stage disease resulted from a new study in the first issue for November 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
Researchers identified 111 families with members who had familial interstitial pneumonia (pulmonary fibrosis). Among the group were 309 affected persons and 360 unaffected. Other than genetic susceptibility, three additional traits were associated with the development of this disease: older age (over 68), male sex, and ever having smoked cigarettes.
During the development of pulmonary fibrosis, certain diseases cause the abnormal accumulation of inflammatory cells in the lungs. As part of the process, white blood cells and protein rich fluid accumulate in the air sacs (alveoli), causing inflammation. When the inflammation persists, the fluid solidifies and scarring or fibrosis replaces lung tissue.
The investigators pointed out that after controlling for the age and sex of the participants, ever having smoked cigarettes remained strongly associated with the presence of pulmonary fibrosis. Yet, even among smokers, genetic susceptibility played a more important role.
Within the 111 families, there were 231 persons with probable pulmonary fibrosis (also called interstitial pneumonia) and 78 with definite disease. Those who had definite disease died at a younger age, had a higher mortality rate, and had a shorter time to death from their age at diagnosis.
According to the authors, the age range at onset of the disease varied greatly from slightly over 30 to over age 75.
TUBERCULOSIS BLOOD TEST BELIEVED SUPERIOR TO SKIN TEST
Researchers who tested the traditional tuberculin skin test against a new tuberculin blood test in persons who had been exposed to a diagnosed tuberculosis (TB) case believe that the new blood assay test could be more sensitive than the skin test in detecting latent TB, especially in foreign-born individuals. Many of these persons had received a type of vaccination that triggered a response from the skin test.
During their research, the investigators studied 413 contacts of patients with TB. Of this group, 185 persons (45 percent) were born in the U.S., and 228 were foreign-born. After both tests were administered, 208 (50 percent) were positive to the tuberculin skin test and 163 (39 percent) were positive to the blood test, called ELISPOT, for which blood was drawn after placement of the skin test. The tuberculin skin test alone was positive in 75 cases (18 percent) and the ELISPOT test alone was positive alone in 30 cases (7 percent).
During the test, six contacts were diagnosed with tuberculosis. Five had positive blood tests and four showed positive tuberculin skin tests.
The authors point out that the tuberculin skin test has many shortcomings. For example, the test requires two office visits and skilled personnel are essential to properly place and interpret the test. Also, the skin test reacts to bacilli Calmette-Guérin (BCG) tuberculosis vaccination which had been given to 201 (88 percent) of the 228 foreign-born persons tested in the study. Among the 185 persons born in the U.S., only three had been BCG vaccinated.
The investigators noted that a more accurate and convenient test to diagnose latent TB infection would greatly enhance control efforts.
ELISPOT, approved for use in Europe, is being evaluated by the U.S. Food and Drug Administration.
The study is published in the first issue for November 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
Journal
American Journal of Respiratory and Critical Care Medicine