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 .
COPD association and repeatability of blood biomarkers in the ECLIPSE cohort
Background There is a need for biomarkers to better characterise individuals with COPD and to aid with the development of therapeutic interventions . A panel of putative blood biomarkers was assessed in a subgroup of the Evaluation of COPD Longitudinally to Identify Surrogate Endpoints ( ECLIPSE ) cohort . Methods Thirty-four blood biomarkers were assessed in 201 subjects with COPD , 37 ex-smoker controls with normal lung function and 37 healthy non-smokers selected from the ECLIPSE cohort . Biomarker repeatability was assessed using baseline and 3-month sample s. Intergroup comparisons were made using analysis of variance , repeatability was assessed through Bl and -Altman plots , and correlations between biomarkers and clinical characteristics were assessed using Spearman correlation coefficients . Results Fifteen biomarkers were significantly different in individuals with COPD when compared to former or non-smoker controls . Some biomarkers , including tumor necrosis factor-α and interferon-γ , were measurable in only a minority of subjects whilst others such as C-reactive protein showed wide variability over the 3-month replication period . Fibrinogen was the most repeatable biomarker and exhibited a weak correlation with 6-minute walk distance , exacerbation rate , BODE index and MRC dyspnoea score in COPD subjects . 33 % ( 66/201 ) of the COPD subjects reported at least 1 exacerbation over the 3 month study with 18 % ( 36/201 ) reporting the exacerbation within 30 days of the 3-month visit . CRP , fibrinogen interleukin-6 and surfactant protein-D were significantly elevated in those COPD subjects with exacerbations within 30 days of the 3-month visit compared with those individuals that did not exacerbate or whose exacerbations had resolved . Conclusions Only a few of the biomarkers assessed may be useful in diagnosis or management of COPD where the diagnosis is based on airflow obstruction ( GOLD ) . Further analysis of more promising biomarkers may reveal utility in subsets of patients . Fibrinogen in particular has emerged as a potentially useful biomarker from this cohort and requires further investigation . Trial Registration SCO104960 , clinical trials.gov identifier
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 .