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 .
Minimally important change values of a measurement instrument depend more on baseline values than on the type of intervention.
OBJECTIVES Multi-item question naires are frequently used to measure outcomes in r and omized controlled trials ( RCTs ) in patients with sciatica . Knowing the minimaly important change ( MIC ) values for these instruments will facilitate interpretation of change scores . MIC values have been shown to be dependent on baseline values . The question is whether they also depend on the type of intervention . To estimate the MIC of the Rol and Morris Disability Question naire ( modified 23 item version ) ( RMDQ ) and of intensity of leg pain measured by a  Visual Analogue Scale  ( VAS ) in patients with sciatica and to assess to what extent MIC values depend on type of intervention and on baseline values . STUDY DESIGN AND SETTING This is a secondary analysis of RCT data of the effects of early surgery vs. prolonged conservative treatment in patients with sciatica . Baseline and 8-week data were used to assess MIC of the RMDQ-23 and VAS leg pain . We used the receiver operator characteristic ( ROC ) method to assess the MIC . Global Perceived Recovery ( rated 8 weeks after baseline ) was used as anchor . Subgroups were created based on type of treatment and baseline severity . RESULTS The MIC value of the RMDQ-23 for the total group of sciatica patients was 7.5 . The values were 8.1 and 6.9 for surgery and conservative treatment , respectively . For high and low baseline values , the MICs were 9.0 and 4.9 , respectively , irrespective of treatment received . The MIC values of the VAS leg pain were 34.4 for the total group . For surgery and conservative treatment , the MIC values were 38.5 and 30.4 , respectively , whereas for groups with high and low baseline values , MIC values of 53.5 and 17.2 were found . CONCLUSION The MIC values of the RMDQ-23 and VAS leg pain were found to be highly dependent on their baseline values , although the type of intervention appeared to influence the MIC value only slightly
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 .