To evaluate the effectiveness of internet-based self-management of asthma compared to usual care.

Randomised, controlled, multi-centre trial (www.controlled-trials.com; ISRCTN79864465).

From 37 general practices and 1 outpatient department we recruited 200 patients with asthma who had a prescription of inhaled corticosteroids for at least 3 months in the previous year and had access to internet. Patients were randomly assigned to an internet group (n = 101) or a control group (n = 99). Participants in the internet group weekly monitored their asthma control on the internet and received on-line treatment advice, education and coaching by an asthma nurse specialist, next to the usual care. Participants in the control group only received the usual care. The primary outcome measure was asthma related quality of life after 12 months (clinically relevant difference 0.5 on a 7-point scale). Secondary outcome measures were asthma control, lung function, symptom-free days and time to first exacerbation.

Asthma related quality of life improved more in the internet group than in the control group (difference: 0.38; 95%-CI: 0.20-0.56). In the internet group 54% showed a clinically relevant improvement, compared to 27% in the control group (RR: 2.00; 95%-CI: 1.38-3.04). Asthma control improved more in the internet group than in de usual care group (difference: ‑0.47; 95%-CI: ‑0.64 - ‑0.30). After 12 months the percentage of symptom-free days increased with 18.2 and 7.3% in the internet group and control group, respectively (difference: 10.9; 95%-CI: 0.05-21.3). Pre-bronchodilator forced expiratory volume in 1 s (FEV₁) changed with 0.24 and -0.01 l (difference: 0.25; 95%-CI: 0.03-0.47), respectively. Time to first exacerbation did not differ between the 2 groups.

Internet-based asthma self-management leads to improvements in asthma related quality of life, asthma control and lung function, and leads to an increased number of symptom-free days.