Table 1.

List of outcome measures

Outcome measures	Importance	Measure unit	Minimal clinically important difference
Mortality	Criticala
Exacerbation rate	Critical	1. Average reduction in the annual number of exacerbations	1. 25% (a minimum reduction of 0.5 exacerbations per year)
		2. Number of patients who experience 0 exacerbations annually	2. 10 percentage points
Oral corticosteroid-maintenance treatment	Critical	1. Average %-reduction in daily dose (maintenance-treatment)	1. 20% (at least 2.5 mg prednisolone equivalent dose)
		2. Percentage of patients who are discontinued oral corticosteroid-maintenance treatment	2. 5 percentage points
		3. Percentage of patients who experience ≥ 50% reduction of oral corticosteroid treatment	10 percentage pointsb
Lungfunction FEV1	Important	1. Average change in lung function	1. 200 ml
		2. Percentage of patients who experience an improvement of 200 ml or more	2. 15 percentage points
Asthma control	Important	Average change in asthma control. A prioritised list of scores    ACQ 5 (Asthma Control Questionnaire)    ACT (Asthma Control Test)    Other similar questionnaires	ACQ: 0.5 ACT: 3
Quality of life (QoL)	Important	Average change in QoL. A prioritised list of scores    Asthma Quality of Life Questionnaire (AQLQ)    Other questionnaires	AQLQ: 0.5
Serious adverse events (SAEs)	Important	The added number of SAEs	5 percentage points for the added number of SAEs
		Specific subgroups of SAEs, including anaphylaxis is assessed if they are distributed uniformly between the groups	No minimal clinically important difference is reported
Drop-out rate	Important	The percentage of patients who dropped out when the study was completed (difference between intention to treat population and difference between “intention to treat”-population and patients who completed the study)	10 percentage points
Sick leave	Important	Average number of sick leave days per year	5 days/year

For each outcome measure, the importance is indicated, and for critical and important outcome measures the minimal clinically important difference is reported

^aMortality is always considered to be a critical effect goal, albeit not an effective efficacy measure in the assessment of biological drugs in severe asthma. Asthma-related death occurs rarely, and it is therefore not estimated that outcome measure will provide any relevant information. In relation to safety, it is included in outcome measure: serious adverse events (SAEs). Mortality will therefore not act as a separate outcome measure in the assessment of the therapy

^bThe Expert Committee defined this outcome measure after the protocol was approved as data could not be extracted for the average OCS reduction