EXTRINSIC AND INTRINSIC ASTHMA FROM CHILDHOOD TO ADULT AGE - A 10-YR FOLLOW-UP

Background: Asthma constitutes one of the most common chronic diseases in childhood, yet little is known about the factors that determine the outcome in childhood asthma. The purpose of this study was to describe various factors of potential importance for the outcome in children with intrinsic and extrinsic asthma. Methods: Of 85 consecutive children, 5-15 years of age with asthma, 70 (82%) participated in a IO-yr follow-up examination. At the time of referral, all children underwent certain tests for asthma (case history, total IgE, skin prick tests, radioallergosorbent (RAST) tests and specific bronchial provocations). On the basis of these tests, 24 children had intrinsic asthma and 46 children had extrinsic asthma. Results: At the follow-up examination, 60 of the 70 adults (86%, 20 with intrinsic asthma) had current symptoms; 54 of the 60 (90%; 18 with intrinsic asthma) were receiving maintenance therapy. Both FEV(1) %predicted and FEV(1)/FVC increased significantly (from 73% +/- 19% to 92% +/- 17% and from 75% +/- 13% to 80% +/- 12% respectively) from childhood to early adulthood (P<0.0001 and P<0.001, respectively); a matching amelioration of symptoms was observed (P<0.0001). Adults with current symptoms had a significantly lower FEV(1) %predicted at the time of follow-up (90% +/- 2% vs. 100% +/- 4%, P<0.02) but not in childhood (73% +/- 20% vs. 71% +/- 10%) than adults who had ceased wheezing. Conclusions: In children with intrinsic asthma, the outcome seems to be predicted by a combination of the initial frequency of symptoms (P=0.04), initial FEV(1) (P=0.002), active smoking (P=0.001) and age at onset of respiratory symptoms (P=0.001), whereas the initial FEV(1) (P<0.001) seems to be a strong predictor for the outcome in children with extrinsic asthma. These findings suggest that the pathogenic mechanisms underlying intrinsic and extrinsic asthma in children may differ.