PURPOSE OF THE STUDY.
To characterize clinical and lung function outcomes of childhood asthma to age 50.
The Melbourne Asthma Study was established in 1964 to describe the spectrum and natural history of childhood asthma. A group of children (n = 401) with a history of wheezing was randomly selected after a survey of 30 000 Melbourne second graders. Another group of children (n = 83) with severe wheezing was selected from the same birth cohort at age 10 years. Reports of wheezing were collected by parent report at recruitment.
The children were recruited in a random sequential process to the following predefined groups: 105 control subjects who had never wheezed; 74 children with <5 episodes of wheezing, typically with respiratory infection (“mild wheezy bronchitis” [MWB]); 104 children with ≥5 episodes of wheezing with respiratory infection (“wheezy bronchitis” [WB]); 113 children with wheezing not associated with infection (persistent asthma); and 83 children (severe asthma) with onset of symptoms before age 3; at least 10 attacks between ages 8 and 10; or persistent symptoms at age 10; barrel-chest deformity; and/or forced expiratory volume in 1 second/forced vital capacity <0.50. The MWB and WB groups would now be classified as intermittent asthma. Subjects were invited to complete an interviewer-administered questionnaire, skin prick testing, and pulmonary function test (PFT) from age 7 to 50 at 7-year intervals.
Of the original 484 subjects, records were lost for 5, 21 others had died (2 from asthma), 78 were lost to follow-up, and 34 refused contact; leaving 346 (76%) who were followed to age 50. Of this group, 57% completed both questionnaire and PFTs, and 43% completed questionnaire alone. Asthma remission at age 50 was 64% in the MWB and WB groups, 47% in those with persistent asthma, and 15% for those with severe asthma. Risk factors for current asthma at age 50 included severe childhood asthma, childhood allergic rhinitis, and female gender. Childhood BMI was not found to be a risk factor. Rates of decline in forced expiratory volume in 1 second (mL/year) were similar in all groups.
The clinical and lung function outcomes in adult life are strongly determined by asthma severity in childhood. Pulmonary function decrements noted in adults are established in childhood, with decline rates similar to persons without asthma.
Previous studies of the natural history of asthma in children have made strikingly similar observations, but those studies did not have 4 decades of follow-up. Although the Melbourne investigators did not record drug therapy, major allergen exposure such as to dust mite or indoor furred pets, allergy immunotherapy, or activity level, the message from “shorter term” studies is that those factors do not determine whether you still have disease decades later. When pediatricians are asked by parents the “Will he/she outgrow asthma” question, the presence of obstructive changes on PFTs, overall more severe disease, and presence of atopy all help steer one’s guarded answer.
- Copyright © 2015 by the American Academy of Pediatrics