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ICD Code: 493. Asthma



ICD Code: 493. Article Review
Title: de Marco R et al; "Incidence and Remission of Asthma: A Retrospective Study on the Natural History of Asthma in Italy." Journal of Allergy and Clinical Immunology; V.110; No.2; 8/02; p228
      STUDY DESIGN: This article describes the pattern of the incidence, persistence, and remission of asthma, from birth to age 44 years, during the period between 1953 and 2000, in a large, nationally representative sample of young Italian adults who took part in the multicenter Italian Study on Asthma in Young Adults. The survey was carried out between 1998 and 2000 in 9 Italian centers belonging to 2 different climatic regions: subcontinental (Northern Italy) and Mediterranean (Central/Southern Italy). The presence of lifetime asthma and age at onset were identified on the basis of the answers the subjects gave to the following questions: (1) "Have you ever had asthma?", and (2) "How old were you when you had your first attack of asthma?" Of the 25,969 eligible subjects in 9 centers, 18,873 filled in the questionnaire, with an overall response rate of 72.7%.
      INCIDENCE (ITALY): The estimated adjusted incidence rates (per 1000 persons per year) of asthma for men versus women were reported by age at onset as follows: 0 to 5 years, 5.3 vs 3.8; 5 to 10 years, 4 vs 2.3; 10 to 15 years, 2.3 vs 1.8; 15 to 20 years, 1.5 vs 1.7; 20 to 25 years, 1.4 vs 1.5; 25 to 30 years, 1.3 vs 1.8; 30 to 35 years, 1.8 vs 3.0; 35 to 40 years, 2 vs 3.2; 40 years and older, 2 vs 5.3.
      The crude incidence of asthma (per 1000 persons per year) was reported as follows. Whole sample: 2.59. Gender: males, 2.76; females, 2.42. Age at onset: 0 to 5 years, 5.17; 5 to 10 years, 3.56; 10 to 15 years, 2.32; 15 to 20 years, 1.67; 20 to 25 years, 1.40; 25 to 30 years, 1.48; 30 to 35 years, 1.96; 35 to 40 years, 1.87; 40 to 45 years, 2.27. Birth cohort: 1953 to 1958, 1.59; 1959 to 1963, 2.09; 1964 to 1968, 2.56; 1969 to 1973, 3.57; 1974 to 1979, 4.73. Climatic region: subcontinental, 2.48; Mediterranean, 2.86. The overall crude incidence was 2.59 per 1000 persons per year (2.76 per 1000 persons per year in men and 2.42 per 1000 persons per year in women), which peaked in the less than 10 years age group and increased in successive generations.
      REMISSION: 663 (45.8%) of 1449 asthmatic subjects remitted, and the percentage of remission was significantly higher in men (49.5%) than in women (41.6%). Subjects in remission were characterized by an earlier mean age at onset (7.4 versus 15.9 years) and a shorter duration (5.6 versus 16.1 years) of the disease than subjects with current asthma. The probability of remission was strongly influenced by the age at onset, being particularly high in children (patients under 10 years of age). The cumulative remission rates were 62.8%, 40.3%, and 15.0%, respectively, in the groups with ages at onset of less than 10 years, 10 to 20 years, and 20 years and older. If the remission of asthma does not occur in the first years after the onset, the disease tends to become chronic.
      DISCUSSION: The authors believe the present study to be one of the largest population-based studies on asthma, allowing the natural history of the disease to be studied retrospectively. It relies on the recall of past events of persons interviewed at one point in time. Its strength is that it gives information on incidence and remission in a wide age range from birth to adult life that would hardly have been possible to obtain by means of a longitudinal study. Its weakness is that recall bias could have influenced the recall of events experienced in the past. The main result of the present retrospective analysis is the evidence that, with respect to its natural history, asthma presents 2 different forms, which the authors call early- and late-onset asthma. The former occurs early in childhood, affects mainly boys, and has a good prognosis; the latter generally occurs during or after puberty, affects mainly women, and has a poor prognosis. A minority of subjects with early-onset asthma, representing about 35% of subjects with current asthma in the young adult population, have long-term persistent asthma. When using prevalence cases in risk-factor assessment, it is necessary to distinguish between subjects with early- and late-onset asthma to avoid confusion between determinants of persistence and determinants of occurrence of asthma.

Search Criteria: Text - Journal of Allergy and Clinical Immunology; V.110; No.2; 8/02; p228