Definitions of severity based on self-reported symptoms and recommended minimum preventer therapy
| Severity | Frequency of self-reported symptoms* | Minimum adequate preventer medication |
| Asymptomatic asthma | No symptoms last year but on asthma medication | None |
| Intermittent asthma | Symptoms in the last year but not in the last month, ⩽3 flare-ups in the last year | None† |
| Mild persistent asthma | Symptoms in the last month but less than weekly, ⩾4 flare-ups in the last year but less than monthly | ICS alone low dose (200 μg BDP/160 μg CIC/200 μg FP/400 μg BUD) daily |
| Moderate persistent asthma | Symptoms more than once weekly but not daily, flare-ups more than monthly in the last year | ICS (200 μg BDP/400 μg BDP/160–320 μg CIC/200–400 μg FP/400–800 μg BUD) plus LABA daily |
| Severe persistent asthma | Symptoms daily and flare-ups more than weekly in the last year | High dose of ICS (>400 μg BDP/>320 μg CIC/>400 μg FP/>800 μg BUD) daily |
BDP, beclomethasone dipropionate HFA aerosol; BUD, budesonide; CIC, ciclesonide; FP, fluticasone propionate; ICS, inhaled corticosteroid; LABA, long-acting β2 agonist.
*Self-reported symptoms of (1) morning, (2) daytime, (3) night-time symptoms and (4) number of flare-ups.
†Participants with intermittent asthma who were on preventer medication were categorised as “adequate preventer medication users” since, according to the NAC guidelines, they did not require being on preventer therapy.