LAUSR

Simply stated, clinically important difference (CID) is the difference in outcome scores between 2 groups that can be considered clinically relevant. The notion of CID began as a way to assist in the interpretation of quality-of-life instruments and other patient-reported outcomemeasures (PROM). It was introduced initially as the minimal clinically important difference (MCID) and later as the minimal important difference (MID), which omits the “clinical” to allow for use with laboratory or functional tests. Clinically important difference focuses on the perceptions of patients or clinicians and reflects a change in outcomes that is not necessarily minimal. The table below summarizes the variations in terminology the reader may encounter (Table 1).