Table 1 Metrics of clinically important changes

Smallest detectable difference (SDD)

The amount of difference in an outcome measure for which anything smaller cannot be reliably distinguished from random error in the measurement

Minimal detectable change (MDC)

Minimal clinically important difference (MCID)

The smallest change or difference in an outcome measure between pre- and post-treatment perceived as beneficial (or detrimental) by the patient [7-9]

Can be used to measure improvement and worsening

Minimal clinically important change (MCIC)

Minimal clinically important improvement (MCII)

Only measures improvements

Clinically important difference (CID)

The difference in outcome measure that is considered clinically important/meaningful