Also called “minimally important difference” or in a slightly different form, “minimally clinically important improvement.” This term refers to the smallest amount of change or effect from a treatment that matters to a patient or would result in a change in a patient’s care. For example, if a doctor is contemplating changing a patient’s medication from drug A to drug B, the minimally clinically important difference might be a 10 percent reduction in risk or a 10 percent improvement in pain. If drug B only offers, say, an 8 percent improvement, that falls below the threshold necessary for the doctor to make the change, which may especially be relevant if drug B’s side effects are more troublesome. MCID (or MID or MCII) is especially relevant for considering the clinical significance of a research finding.
