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 .
What is an acceptable outcome of treatment before it begins? Methodological considerations and implications for patients with chronic low back pain
Underst and ing changes in patient-reported outcomes is indispensable for interpretation of results from clinical studies . As a consequence the term “ minimal clinical ly important difference ” ( MCID ) was coined in the late 1980s to ease classification of patients into improved , not changed or deteriorated . Several method ological categories have been developed determining the MCID , however , all are subject to weaknesses or biases reducing the validity of the reported MCID . The objective of this study was to determine the reproducibility and validity of a novel method for estimating low back pain ( LBP ) patients ’ view of an acceptable change ( MCIDpre ) before treatment begins . One-hundred and forty-seven patients with chronic LBP were recruited from an out-patient hospital back pain unit and followed over an 8-week period . Original and modified versions of the Oswestry disability index ( ODI ) , Bournemouth question naire ( BQ ) and numeric pain rating scale  ( NRSpain ) were filled in at baseline . The modified question naires determined what the patient considered an acceptable post-treatment outcome which allowed us to calculate the MCIDpre . Concurrent comparisons between the MCIDpre , instrument measurement error and a retrospective approach of establishing the minimal clinical ly important difference ( MCIDpost ) were made . The results showed the prospect i ve acceptable outcome method scores to have acceptable reproducibility outside measurement error . MCIDpre was 4.5 larger for the ODI and 1.5 times larger for BQ and NRSpain compared to the MCIDpost . Furthermore , MCIDpre and patients post-treatment acceptable change was almost equal for the NRSpain but not for the ODI and BQ . In conclusion , chronic LBP patients have a reasonably realistic idea of an acceptable change in pain , but probably an overly optimistic view of changes in functional and psychological/affective domains before treatment begins
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 .