Background Severe asthma can be due difficult to treat asthma due to poor adherence or due to refractory asthma. Identifying poor adherence can be challenging since the methods of adherence have limitations. We developed a method of assessing adherence using Inhaler compliance assessment (INCA) device, which incorporates both identifying technique errors and time of use of the inhaler. We hypothesised that that feedback on time of use and technique of use to patients, improves adherence, compared to standard education without visual feedback.

Methods This was a 3-month prospective multicentre randomised controlled stud, in which patients with severe uncontrolled asthma recruited from specialist asthma clinics were randomised to get feedback on and education using the adherence information downloaded from the INCA device or education alone.

Results At the end of the study period, the mean rate of adherence for month three in the active group (n = 111) was 73% versus 63% in the control group (n = 107), p ≤ 0.01 (95% CI: difference 2.8, 17.6). Only the active group demonstrated significant reductions in the rate of technique errors missed doses, excess-doses with improvement in the habit of use. The mean AQLQ and ACT improved significantly in both groups. At the end of the study, 64 (32%) patients remained poorly controlled with persistent airflow obstruction. Of these, 39 had adherence rates <80%, (mean 52%), while 25 had adherence >80%, indicating refractory asthma.

Conclusion Without changing patients’ therapy, most of the patients’ asthma control improved. Two thirds of those who remained uncontrolled required further adherence counselling. 11% of the total cohort remained unstable despite adequate adherence and hence will require step up therapy. Our study shows that adherence assessment and education using INCA feedback should be considered prior to referring patients for additional therapy.