Figure 1

Study flow diagram. Medical records of cases who were referred in the period between January 1990 and December 1991 to the clinic for the diagnosis and treatment of allergic diseases were reviewed. To be included in the study cases had to be between the ages of 18 and 40 years and not diagnosed with asthma at the time of referral. A total of 1104 records were selected at baseline. In the period from January to April 2000, subjects were contacted for a follow up visit to evaluate the possibility of asthma diagnosis; 629 subjects were lost to follow-up leaving 475 subjects taking part in the study. A diagnosis of asthma could not be established with confidence in 39 subjects, leaving a total of 436 subjects for the final analyses. Among those 436 subjects, 332 had allergic rhinitis and 104 had no allergic rhinitis or history of atopy. At follow up, 46.1% (n = 153) of those with rhinitis at baseline developed asthma.