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 .
Sufficiently Important Difference
Evidence -based medicine is built on a foundation of r and omized trials . Interpretation of trials depends on whether a predetermined difference ( effect size ) between intervention and control groups was observed and the likelihood of this being due to chance ( statistical significance ) . It is now generally agreed that the effect size for which a trial is powered should be just large enough to be clinical ly significant . Introduction of the concept of minimal important difference ( MID ) in the 1980s was followed by an emerging stream of research aim ed at assessing this quantity in a variety of disease conditions , followed by rapidly increasing use of MID among research ers and regulators . To date , however , MID methods focus on benefit magnitude alone , ignoring side effects , adverse events , and other harms . This article 1 ) argues that MID should be replaced with ‘ ‘ sufficiently important difference ’ ’ ( SID ) , a concept that includes balancing of benefits against harms , and 2 ) outlines a few pressing research questions and challenges related to this incipient field . Sufficiently important difference was originally defined as ‘ ‘ the smallest amount of patient-valued benefit that an intervention would require to justify associated costs , risks and other harms . ’ ’ SID is understood in the context of existing evidence and is measured at the individual level . Perhaps the concept underlying SID should instead been named ‘ ‘ smallest worthwhile effect ’ ’ ( SWE ) , as that phrase seems to have more intuitive appeal . Because people value various benefits and harms differently , SID/SWE varies across population s. Because the assessment of benefits and harms changes as science evolves , SID/SWE estimates may change . Yet even in relatively evolved and evidence -rich areas , such as preventing and treating cardiovascular disease or screening for breast or colon cancer , questions regarding SID/SWE lie almost completely unexplored . For example , we do n’t know whether closer to 10 % , 50 % , or 90 % of people targeted for cholesterol , blood pressure , or blood sugar – lowering drugs or for cancer screening using colonoscopy or mammography would deem expected benefits sufficient to justify expected harms , should they underst and the evidence . We know that these interventions are widely promoted and that some benefits are expected , but we do n’t know whether or to what degree that associated benefit-harm tradeoffs correspond to target population health values . Although great progress has been made in the evidence -based assessment of benefits and harms , very little is known about how individuals and population s would value and use that evidence in decision making , should it be presented to them in an underst and able manner . The purpose of this article , then , is to call for an expansion of inquiry in this direction , to suggest a few research questions and method ological avenues , and to briefly list some of the challenges that may emerge . Arguably , the era of evidence -based medicine ( EBM ) began with Archie Cochrane , after whom the Cochrane collaboration was named . Cochrane , followed by notables such as Gordon Guyatt , David Sackett , and others , exhorted the medical Received 15 February 2012 from Department of Family Medicine , University of Wisconsin – Madison , Madison , WI ( BB ) . Revision accepted for publication 5 December 2012
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 .