Absolute MCID was strongly associated with baseline pain , explaining approximately two-thirds of the variation , and to a lesser degree with the operational definition of minimum pain relief and clinical condition .
MCID  for chronic pain relief vary considerably .
Baseline pain is strongly associated with absolute , but not relative , measures .
To a much lesser degree , MCID is also influenced by the operational definition of relevant pain relief and possibly by clinical condition .
BACKGROUND The minimum clinical ly important difference ( MCID ) is used to interpret the relevance of treatment effects , e.g. , when developing clinical guidelines , evaluating trial results or planning sample sizes .
There is currently no agreement on an appropriate MCID in chronic pain and little is known about which context ual factors cause variation .
METHODS This is a systematic review .
Responsiveness of fibromyalgia clinical trial outcome measures.
OBJECTIVE To assess the responsiveness of the Fibromyalgia Impact Question naire ( FIQ ) , patient ratings of pain intensity , number of tender points , and total tender point pain intensity score to perceived changes in clinical status in patients with fibromyalgia ( FM ) . METHODS Using data from a r and omized  placebo controlled study evaluating efficacy of magnetic therapy in patients with FM , the ability of primary outcomes to detect clinical ly meaningful changes over a 6 month period was assessed by : ( 1 ) degree of association between outcome change scores and patient global ratings of symptom change ( Spearman rank-order correlations ) ; ( 2 ) ability of these scores to discriminate among groups of patients whose perceived health status had changed to varying degrees ( ANOVA ) ; ( 3 ) ability of these scores , individually and jointly , to discriminate between patients who had reported improvement and those who did not ( logistic regression ) ; ( 4 ) effect size , st and ardized response mean , and Guyatt 's statistic were calculated to quantify responsiveness . RESULTS Correlations showed the outcome measures were moderately responsive to perceived symptomatic change . For FIQ , pain intensity ratings and number of tender points , differences in change scores between globally improved and unchanged groups and between globally improved and worsened groups were significant ; for total tender point pain intensity , the globally improved differed from worsened group . FIQ outperformed the other measures in discriminating between patients who reported improvement from those who did not . Summary statistics were consistent with discriminatory analyses , indicating the measures were sensitive to improvement , but relatively unresponsive to decline . CONCLUSION The FIQ was the most responsive measure to perceived clinical improvement and we recommend its inclusion as a primary endpoint in FM clinical trials
Absolute MCID was strongly associated with baseline pain , explaining approximately two-thirds of the variation , and to a lesser degree with the operational definition of minimum pain relief and clinical condition .
MCID  for chronic pain relief vary considerably .
Baseline pain is strongly associated with absolute , but not relative , measures .
To a much lesser degree , MCID is also influenced by the operational definition of relevant pain relief and possibly by clinical condition .
BACKGROUND The minimum clinical ly important difference ( MCID ) is used to interpret the relevance of treatment effects , e.g. , when developing clinical guidelines , evaluating trial results or planning sample sizes .
There is currently no agreement on an appropriate MCID in chronic pain and little is known about which context ual factors cause variation .
METHODS This is a systematic review .