The CATO population is a very well documented population during two years. During this study patients were treated according to the CATO algorithm, after that patient were treated according to the Dutch national (GINA derived) guidelines up to 6 years of follow-up. The purpose of this prospective follow-up study is to understand the long-term effects of treatment. Therefore the measurements done at baseline (CATO part 1) are repeated after 6 years in this CATO-population (CATO follow-up).

A long term follow up study for a comparison of stepwise treatment of asthmatic children with Salmeterol/Fluticasone propionate combination product (Seretide®) and/or Fluticasone propionate (Flixotide®) based on PD20 methacholine and symptoms or based on symptoms only ("Children Asthma Therapy Optimal")

Inclusion criteria:

• Any subject who has given informed consent to participate in the CATO study, and has met all the criteria required for randomisation into the clinical study may take part in this follow up study
• Under the age of 18 years Subjects and both parent(s)/guardian(s) who have given written informed consent to participate in the study
• Subjects from 18 years and older who have given written informed consent to participate in the study

Exclusion criteria:

• Experienced an acute asthma exacerbation requiring emergency room treatment within 4 weeks or hospitalisation within 4 weeks of visit 1
• Any use of oral/parenteral or depot corticosteroid within 4 weeks of visit 1
• Subjects who are pregnant (a pregnancy test can be performed at the investigator's discretion)

All patients randomized in the CATO study (SAS30018) (total of 210) were asked to participate in the follow up study.

Any subject who gave informed consent to participate in the CATO study, and met all the criteria required for randomisation into the clinical study took part in this follow up study.