In Finnish young men, the incremental tendency of asthma diagnosis remained from 0.29% in 1966 to 1.79% in 1989. The possibility of confounding factors in the diagnosing is improbable, as the exemption of military service due to incapacitating asthma was correlated with the increase reported.
In another wider evaluation in the UK, from 1955 to 2004, several indicators of asthma such as primary care, prescriptions, hospitalizations, and mortality evidenced an increase until the 1990s, where the curve flattened and even decreased The opposing evolution of these effects compared to the sale of inhaled corticosteroids (ICS) is one explanation, since the recognition of the inflammatory component of asthma began in the 1980s.
However, also in the UK, an evaluation of prevalence in schoolchildren between 1991 and 2002 showed a significant increase in wheezing in the past 12 months, in severe speech-limiting episodes and night waking, but non-significant increase in medical visit because of wheezing. Here again, this last finding could be explained by the significant increase in steroids prophylactic treatment reported in this population.
This explanation will be reconsidered ahead.
Another trend study also evidenced a significant increase from 1990 to 2003 in doctor-diagnosed asthma, more evident in females (7.3–14.6%) than in males (7.8–9.4%), in all age groups but larger in people aged 55 and older.