There was no consistent relationship with factors such as disease-specific or generic instrument or the number of response options .
Negative changes were not associated with larger ESs .
Population -based estimation procedures and brief follow-up were associated with smaller ESs , and acute conditions with larger ESs .
Background .
A number of studies have computed the minimally important difference ( MID ) for health-related quality of life instruments .
To determine whether there is consistency in the magnitude of MID estimates from different instruments .
What are minimal important changes for asthma measures in a clinical trial?
In this study , the perceptions of asthmatics to change in their disease was associated with observed changes in clinical asthma measures , in order to identify the threshold where changes in clinical asthma measures are perceivable by patients . The study included 281 asthmatic patients , aged 18 - 63 yrs , in a r and omized , placebo-controlled clinical trial of a leukotriene antagonist .  Changes were related in : 1 ) asthma symptom scores ; 2 ) inhaled beta-agonist use ; 3 ) forced expiratory volume in one second ( FEV1 ) ; and 4 ) peak expiratory flow ( PEF ) to a global question that queried overall change in asthma since starting the study drug . Additional analyses examined differences in the group reporting minimal improvement by treatment ( active treatment versus placebo ) , sex and age groups . The average minimal patient perceivable improvement for each measure was : 1 ) -0.31 points for the symptom score on a scale of 0 - 6 ; 2 ) -0.81 puffs x day(-1 ) for inhaled beta-agonist use ; 3 ) 0.23 L for FEV1 ; and 4 ) 18.79 L x min(-1 ) for PEF . In general placebo-treated patients and older patients , who reported minimal improvement , experienced less mean improvement from baseline than active-treated patients and younger patients , who reported minimal improvement . Determining the minimal patient perceivable improvement value for a measure may be helpful to interpret changes . However , interpretation should be carried out cautiously when reporting a single value as a clinical ly important change
There was no consistent relationship with factors such as disease-specific or generic instrument or the number of response options .
Negative changes were not associated with larger ESs .
Population -based estimation procedures and brief follow-up were associated with smaller ESs , and acute conditions with larger ESs .
Background .
A number of studies have computed the minimally important difference ( MID ) for health-related quality of life instruments .
To determine whether there is consistency in the magnitude of MID estimates from different instruments .