Thus the distribution method can only be used to calculate an absolute MCID as there is no st and ard deviation of baseline score for a relative measure .
The anchor-based method relates the change in
To the Editor : The same patient outcome data from clinical trial results , when presented as absolute or relative changes , may appear different in magnitude .
Recommendations are to report both absolute and relative , or at least baseline , data from which to calculate absolute values [ 1 , 2 ] .
To inform clinical practice , outcome improvements , whether relative or absolute , must be statistically significant and clinical ly meaningful .
A minimal clinical ly important difference ( MCID ) should inform sample size calculations for clinical trials .
Sputum eosinophilia and short-term response to prednisolone in chronic obstructive pulmonary disease: a randomised controlled trial
BACKGROUND Some patients with chronic obstructive pulmonary disease ( COPD ) respond to corticosteroid therapy . Whether these patients have different airway pathology from other COPD patients is unclear . We tested the hypothesis that response to prednisolone is related to the presence of eosinophilic airway inflammation . METHODS We did a r and omised , double-blind , crossover trial . Patients who had COPD treated with bronchodilators only were assigned placebo and 30 mg prednisolone daily for 2 weeks each , in a r and om order , separated by a 4-week washout period . Before and after each treatment period , we assessed patients with spirometry , symptom scores , the chronic respiratory disease question naire ( CRQ ) , incremental shuttle walk test , and induced sputum .  Analysis was done by intention to treat . FINDINGS 83 patients were recruited , of whom 67 were r and omised . The geometric mean sputum eosinophil count fell significantly after prednisolone ( from 2.4 % to 0.4 % ; mean difference six-fold [ 95 % CI 3.1 - 11.4 ] ) but not after placebo . Other sputum cell counts did not change . After stratification into tertiles by baseline eosinophil count , postbronchodilator forced expiratory volume in 1 s ( FEV1 ) and total scores on the CRQ improved progressively after prednisolone from the lowest to the highest eosinophilic tertile , compared with placebo . The mean change in postbronchodilator FEV1 , total CRQ score , and shuttle walk distance with prednisolone compared with placebo in the highest tertile was 0.19 L ( 0.06 - 0.32 ) , 0.62 ( 0.31 - 0.93 ) , and 20 m ( 5 - 35 ) , respectively . INTERPRETATION Our findings suggest that eosinophilic airway inflammation contributes to airflow obstruction and symptoms in some patients with COPD and that the short-term effects of prednisolone are due to modification of this feature of the inflammatory response . The possibility that sputum eosinophilia identifies a subgroup of patients who particularly respond to long-term treatment with inhaled corticosteroids should be investigated
Thus the distribution method can only be used to calculate an absolute MCID as there is no st and ard deviation of baseline score for a relative measure .
The anchor-based method relates the change in
To the Editor : The same patient outcome data from clinical trial results , when presented as absolute or relative changes , may appear different in magnitude .
Recommendations are to report both absolute and relative , or at least baseline , data from which to calculate absolute values [ 1 , 2 ] .
To inform clinical practice , outcome improvements , whether relative or absolute , must be statistically significant and clinical ly meaningful .
A minimal clinical ly important difference ( MCID ) should inform sample size calculations for clinical trials .