Study show asthma does not remit at adolescence
Contrary to the commonly held belief that asthma in children frequently disappears during adolescence, researchers have found in a study that almost 60 percent of the children with asthma during the pre-pubertal period keep experiencing wheezing episodes during the first four years after the onset of puberty. Also, from their study results, the investigators revealed that being either overweight or obese at age 11 was associated with a threefold increased risk for the persistence of asthma. The study authors analyzed data on 781 children from a longitudinal birth cohort called the Tucson Children's Respiratory Study. The investigators examined the youngsters at ages 6,8,11, 13, and 16 years to determine factors influencing the persistence or the remission of childhood asthma after the onset of puberty, which was considered to be 12.2 years. A major finding of the study was the strong, independent effect of elevated body mass index and the early onset of puberty on the persistence of wheezing in adolescence. Of the 781 children in the study, 166 were considered asthmatics either as a result of frequent wheezing or a physician-confirmed diagnosis, plus wheezing. Of this group, 58 percent of the children, or 97 kids, reported the presence of wheezing after the onset of puberty. In contrast, only 30 percent of the children with infrequent wheezing before puberty experienced wheezing after the onset of puberty. The study appears in the first issue for July 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
Japanese investigators develop new tuberculosis test
Japanese investigators, using an interferon-gamma-based whole blood assay that features new antigens, have developed a highly accurate diagnostic test to detect tuberculosis (TB) infection in persons who have received the Calmette-Guérin (BCG) vaccination, which has been employed in many countries primarily to reduce the severity of the disease. (Because BCG vaccine is not 100 percent effective, it is not routinely given to children in the U.S.) The researchers said that the current tuberculin skin test used to indicate Mycobacterium tuberculosis infection has many limitations, including being confounded by BCG vaccination and by the presence of nontuberculosis mycobacteria. After identifying several antigens that are absent from BCG vaccine as well as from most nontuberculosis mycobacteria, the investigators used them in a whole blood interferon-gamma assay as a diagnostic test in BCG-vaccinated persons. Utilizing a group of 216 BCG-vaccinated Japanese adult student nurses who had no identifiable risk of tuberculosis exposure, they found that the specificity of their new test was 98.1 percent. (The specificity of a test is the percentage of people reliably classified as not having the disease.) Employing the same test on a group of 118 patients with diagnostic culture-confirmed M. tuberculosis infection who had received no therapy, they found a sensitivity of 89 percent. (Sensitivity to a test is the percentage of people reliably classified as having the disease.) The specificity of the tuberculin skin test in the study was 35.4 percent, but was only 10 percent in public reports in Japan. The investigators attributed the poor skin test specificity to a widespread use of the BCG vaccine in that country. Commenting in a editorial on the study in the same issue of the journal, Peter F. Barnes, M.D., of the Center for Pulmonary and Infectious Disease Control, University of Texas Health Center, Tyler, Texas, wrote that the research offered the most convincing evidence to date that the interferon-gamma-based tests are substantially more specific in BCG-vaccinated persons. He points out that the most critical issue for further evaluation of the interferon-gamma-based test is to determine its sensitivity for detection of latent tuberculosis infection. The study appears in the first issue for July 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
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Journal
American Journal of Respiratory and Critical Care Medicine