Outcome and severity of adult onset asthma--report from the obstructive lung disease in northern Sweden studies (OLIN).
BACKGROUND
Studies of longitudinal changes in severity and the long-term outcome of asthma in epidemiological settings are uncommon.


OBJECTIVE
To assess the outcome of incident asthma in a cohort of subjects who developed asthma after the age of 20 years.


METHODS
This is a prospective study of the outcome of 309 subjects with incident asthma being included in a case-referent study based on all adults aged 20-60 years living in three municipalities/towns in Northern Sweden. The subjects fulfilled the criteria for incident asthma defined as onset of symptoms common in asthma within 12 months prior to the study and a verified bronchial variability. In 2003, 250 (81%) of the subjects with asthma were re-examined with structured interview, lung-function test and methacholine test.


RESULTS
At follow-up, 237 (95%) subjects still had an active asthma, i.e. they had symptoms or used asthma medicines. Among those with active asthma, 65% were using inhaled cortico-steroids. Severity grading (GINA 2000) showed that 21% had mild intermittent asthma, 30% mild persistent, 44% moderate persistent, and 5% severe asthma, contrasting to 75% with moderate or severe asthma at entry. Higher age, higher BMI and low lung function were associated with greater asthma severity. Twelve subjects (5%) were in remission. Predictors for remission were non-sensitisation and a normal lung function. Age, sex, BMI, and smoking habits were not significantly different between those in remission and those not.


CONCLUSIONS
Remission of adult onset asthma was low. Severity of asthma changed considerably over time, however, the overall change was towards a milder disease probably as a result of treatment.
Rönmark
Eva
E
The OLIN Studies, Department of Medicine, Sunderby Central Hospital of Norrbotten, Luleå, Sweden. eva.ronmark@telia.com
Lindberg
Anne
A
Watson
Louise
L
Lundbäck
Bo
B
D000328:Adult; D017668:Age of Onset; D001249:Asthma / Q000453:epidemiology* / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D011446:Prospective Studies; D012075:Remission, Spontaneous; D012720:Severity of Illness Index; D013548:Sweden / Q000453:epidemiology