The Minimally Important Clinical Difference.

The minimally important clinical difference (MCID) is the smallest measureable change in outcome score that will make a difference to the patient. MCID is usually estimated either as the smallest difference that can be detected statistically, or as the difference between patients who respond positively and negatively to an anchor question.• MCID is the least a surgeon can do which benefits the patient from the patient's perspective.• MCID is necessary information in power analyses used to design new studies comparing treatments.