Remission of asthma: a prospective longitudinal study from northern Europe (RHINE study)

The aim of the present study was to investigate the remission rate of adult asthma in a general population sample in relation to age, sex, asthma symptoms, allergic rhinitis and smoking. A follow-up of the random population samples from the European Community Respiratory Health Survey in Northern Europe was conducted from 1999-2001 on 1,153 individuals (aged 26-53 yrs) with reported asthma. Remission was defined as no asthmatic symptoms in two consecutive years and no current use of asthma medication. Remission rates per 1,000 person-yrs were calculated and Cox regression models, adjusting for confounders, were used to estimate hazard ratios (HR) with 95% confidence intervals (CI). An average remission rate of 20.2 per 1,000 person-yrs was found. There was no significant difference according to sex; the remission rates were 21.7 and 17.8 per 1,000 person-yrs in females and males, respectively. An increased remission rate was observed among subjects who quit smoking during the observation period. Subjects not reporting any asthma symptom at baseline had an increased remission rate. In the Cox regression model, ex-smoking (HR 1.65, 95% CI 1.01-2.71) was associated with increased remission rate, and reporting any asthma symptom at baseline was associated with decreased remission rate (HR 0.7, 95% CI 0.40-0.90). In conclusion, the present prospective longitudinal study showed that quitting smoking and the presence of mild disease appeared to favour remission.