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ICD Code: 493. Asthma

ICD Code: 493. Article Review
Title: Barbee RA et al; "The Natural History of Asthma." Journal of Allergy and Clinical Immunology; V.102; No.4; Pt.2; 10/98; pS65
      NATURAL HISTORY OF CHILDHOOD ASTHMA: A UK study collected information at birth and at ages 5 and 10 years on a national cohort of 11,465 children. A history of wheezing was obtained through questionnaires administered to the parents. Of the children who had at least 1 wheezing attack before age 5 years, only 20% had 1 or more wheezing attacks at age 9 years. The number of attacks before age 5 years was a strong predictor of prognosis at age 10 years. 50% of the children with a diagnosis of asthma at age 5 years no longer had that diagnosis at age 10 years.
      Results from studies that spanned the years from childhood to adulthood are now available. One such study involved a population enrolled in 1964 at age 7 years, for which 21 years of follow-up had been completed. 43% of subjects who wheezed at age 7 were no longer wheezing at age 28, and 32% had wheezing at least weekly. It is important that the subjects with more severe wheezing at age 28 tended to have lower lung function and greater airway responsiveness. Over time, some asthmatics improved, and an approximately equal number worsened.
      Members of a 1958 birth cohort in the UK have now been monitored up to age 33 years. Parents of the participants were interviewed when the children were ages 7, 11, and 16 years. The participants themselves were interviewed at ages 23 and 33 years. Of children with a report of asthma or wheezy bronchitis before age 7 years, only 10% had wheezing within the preceding year when questioned at age 23. However, at age 33, 27% reported wheezing in the preceding year. For subjects who reported continued wheezing at age 33, forced expiratory volume in one second (FEV-1) was reduced by about 10% compared with the control group.
      Based on several studies, it appears that about 50% of adults who report having had childhood asthma no longer have symptoms. Airway responsiveness in childhood, however, tends to predict airway responsiveness in adulthood, tends to be greater in asthmatics with persistent symptoms, and tends not to improve over time. These studies support the hypothesis that early therapeutic intervention in mild asthma may lead to an improved clinical outcome.
      REAL VS ARTIFACTUAL PREVALENCE TRENDS: Studies designed to determine whether there has been a recent increase in asthma prevalence are difficult to interpret. They have relied almost exclusively on repeated cross-sectional surveys of different populations living under similar conditions. One survey determined the point prevalence of asthma among 17-year-old Israeli males to be 5.0%, with a cumulative prevalence of 7.9%. When the survey was repeated 4 years later, the percentages for these variables were 5.9% and 9.6%, respectively. A similar study in Finland with a 25-year interval found the prevalence of asthma had increased from 4% to 10%. Rather than accept that these changes were solely related to an increase in asthma prevalence, one study addressed the question of diagnostic labeling and the effect that changes may have on asthma prevalence data. They analyzed 16 studies, all of which were conducted with the repeated cross-sectional survey method. Despite the fact that the reports almost universally indicated an increase in asthma prevalence, the authors were skeptical. In their view the added attention given to asthma in recent years including both public and professional information campaigns has led to an increase in and possible overuse of the asthma diagnostic label. In many cases symptoms have increased less than the asthma diagnosis, suggesting that the increased symptom prevalence accounts for only a portion of the reported increase in asthma diagnoses.

Search Criteria: Text - Journal of Allergy and Clinical Immunology; V.102; No.4; Pt.2; 10/98; pS65