We observed a lack of consistency in the application of methods for computing MID or MCID for generic and disease-specific HRQoL measures .
The anchor-based method yields conservative estimates of MID or MCID , compared to the distribution-based method .
OBJECTIVES The objective of the study was to assess the usability of minimal important difference ( MID ) and minimal clinical ly important difference ( MCID ) for measuring meaningful changes in disease-specific and generic health-related quality -of-life ( HRQoL ) outcomes in patient-centered care .
Surveying physicians to determine the minimal important difference: implications for sample-size calculation.
The minimal important difference ( MID ) is the smallest benefit of treatment that would result in clinicians recommending it to their patients . The MID is necessary to calculate sample size for r and omized clinical trials , but its chosen value is often arbitrary . This study set out to determine the practicability of surveying physicians to elicit the MID for clinical trial sample -size calculation . Using a mail survey , we elicited the MID of different physician specialties ( family medicine , internal medicine , vascular surgery ) for using propranolol  to slow abdominal aortic aneurysm ( AAA ) growth assuming that propranolol was efficacious in this condition . We used different outcome measures ( growth rate or proportion of patients requiring surgery ) and different methods of data presentation for the proportion of patients requiring surgery ( absolute risk reduction or number needed to treat ) . The MID varied significantly by physician specialty , experience with AAA and propranolol , and the method used to elicit the MID . Consequently , sample -size calculations using these various MIDs varied from 116 to 3015 . Future attempts to elicit the MID need to consider carefully who is surveyed , how data are presented , and how opinions are elicited
We observed a lack of consistency in the application of methods for computing MID or MCID for generic and disease-specific HRQoL measures .
The anchor-based method yields conservative estimates of MID or MCID , compared to the distribution-based method .
OBJECTIVES The objective of the study was to assess the usability of minimal important difference ( MID ) and minimal clinical ly important difference ( MCID ) for measuring meaningful changes in disease-specific and generic health-related quality -of-life ( HRQoL ) outcomes in patient-centered care .