What is minimal clinically important difference (MCID)?

The minimal clinically important difference (MCID) is a threshold which needs to be met for a given intervention compared to standard of care in order to consider it of clinical relevance. The bar for MCID may be higher than that for statistical significance (although this is not necessary) and if so, a statistically significant result may still be considered not meaningful from a clinical perspective because it is not moving the needle enough for patients. MCIDs are important to consider in study design and evaluation of potential therapeutic compounds in order to ensure that development drugs are able to meet actual clinical needs in a meaningful way. MCID is sometimes also called MID or minimal important difference.