Seeking a diagnosis of asthma depends on how severe it is. This study avoided self selection by following a cohort for 22 years. It found that symptoms of asthma (not diagnosed) and atopy were predictive of adult asthma. The implied defence is that adult asthma was very likely to happen regardless of any specific negligent exposure.
HL Rhodes et al. Journal of Allergy and Clinical Immunology. November (2001) Vol. 108 #5. p. 720.
A longitudinal study of early life risk factors for adult asthma.
Cases of adult onset asthma should regarded as having a potential environmental cause. However, increased severity of asthma in adult life may have an innocent explanation.
Risk factors for adult asthma may be useful in deciding the degree to which other causes are investigated.
This was a prospective cohort study of 100 babies, born to atopic parents. Bronchial hyperresponsiveness was measured at 11 and 22 yrs. Annual check-up in first 5 years.
73 were followed up at 5 years, 67 at 11 years, only 63 at 22 years.
25% were asthmatic as adults. (15 cases).
Wheezing before 2 yrs was not associated with adult asthma.
Wheezing at age 10 was predictive OR = 9.4 (95% CI = 2.1 to 45.5).
Positive skin prick test in year 1 to hens egg, cows milk or both, was predictive OR = 10.7 (95% CI = 2.1 to 55.1). A sign of atopy.
There is a high chance that adult asthma has an innocent cause if there is a history of wheezing at age 10 or if there is evidence of atopy in the first year of life.
The confidence limits on the risk ratios are very high, this reduces confidence in the findings.