There was no consistent relationship with factors such as disease-specific or generic instrument or the number of response options .
Negative changes were not associated with larger ESs .
Population -based estimation procedures and brief follow-up were associated with smaller ESs , and acute conditions with larger ESs .
Background .
A number of studies have computed the minimally important difference ( MID ) for health-related quality of life instruments .
To determine whether there is consistency in the magnitude of MID estimates from different instruments .
Linking clinical relevance and statistical significance in evaluating intra-individual changes in health-related quality of life.
OBJECTIVE To compare the st and ard error of measurement ( SEM ) with established st and ards for clinical ly relevant intra-individual change in an evaluation of health-related quality of life . DESIGN Secondary analysis of data from a r and omized controlled trial . SUBJECTS Six hundred and five out patients with a history of cardiac problems attending the general medicine clinics of a major academic medical center . MEASURES Baseline and follow-up interviews included a modified version of the Chronic Heart Failure Question naire ( CHQ )  and the SF-36 .  The SEM values corresponding to established st and ards for minimal clinical ly important differences ( MCIDs ) on the CHQ were determined . Individual change on the SF-36 was explored using the same SEM criterion . RESULTS One-SEM changes in this population corresponded well to the patient-driven MCID st and ards on all CHQ dimensions ( weighted kappas ( 0.87 ; P < 0.001 ) . The distributions of out patients who improved , remained stable , or declined ( defined by the one-SEM criterion ) were generally consistent between CHQ dimensions and SF-36 subscales . CONCLUSIONS The use of the SEM to evaluate individual patient change should be explored among other health-related quality of life instruments with established st and ards for clinical ly relevant differences . Only then can it be determined whether the one-SEM criterion can be consistently applied as a proxy for clinical ly meaningful change
There was no consistent relationship with factors such as disease-specific or generic instrument or the number of response options .
Negative changes were not associated with larger ESs .
Population -based estimation procedures and brief follow-up were associated with smaller ESs , and acute conditions with larger ESs .
Background .
A number of studies have computed the minimally important difference ( MID ) for health-related quality of life instruments .
To determine whether there is consistency in the magnitude of MID estimates from different instruments .