Minimum Clinically Important Difference (MCID)

A Minimum Clinically Important Difference (MCID) is a treatment assessment method based on the smallest improvement considered worthwhile by a patient.

• Context:
  • It can range from being a Anchor-based MCID to being a Distribution-based MCID.
  • …
• See: MCID, SGRQ.

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References

2007

• (Copay et al., 2007) ⇒ Anne G. Copay, Brian R. Subach, Steven D. Glassman, David W. Polly Jr, and Thomas C. Schuler. (2007). “Understanding the Minimum Clinically Important Difference: A Review of Concepts and Methods.” The Spine Journal 7, no. 5
  • Background context: The effectiveness of spinal surgery as a treatment option is currently evaluated through the assessment of patient-reported outcomes (PROs). The minimum clinically important difference (MCID) represents the smallest improvement considered worthwhile by a patient. The concept of an MCID is offered as the new standard for determining effectiveness of a given treatment and describing patient satisfaction in reference to that treatment.
  • Purpose: Our goal is to review the various definitions of MCID and the methods available to determine MCID.
  • Study design: The primary means of determining the MCID for a specific treatment are divided into anchor-based and distribution-based MCIDs. Each method is further subdivided and examined in detail.
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2005

• (Jones, 2005) ⇒ Paul W. Jones. (2005). “St . George's Respiratory Questionnaire: MCID.” COPD: Journal of Chronic Obstructive Pulmonary Disease 2, no. 1
  • ABSTRACT: The SGRQ is a disease-specific measure of health status for use in COPD. A number of methods have been used for estimating its minimum clinically important difference (MCID). These include both expert and patient preference-based estimates. Anchor-based methods have also been used. The calculated MCID from those studies was consistently around 4 units, regardless of assessment method. By contrast, the MCID calculated using distribution-based methods varied across studies and permitted no consistent estimate. All measurements of clinical significance contain sample and measurement error. They also require value judgements, if not about the calculation of the MCID itself then about the anchors used to estimate it. Under these circumstances, greater weight should be placed upon the overall body of evidence for an MCID, rather than one single method. For that reason, estimates of MCID should be used as indicative values. Methods of analysing clinical trial results should reflect this, and use appropriate statistical tests for comparison with the MCID. Treatments for COPD that produced an improvement in SGRQ of the order of 4 units in clinical trials have subsequently found wide acceptance once in clinical practice, so it seems reasonable to expect any new treatment proposed for COPD to produce an advantage over placebo that is not significantly inferior to a 4-unit difference.

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