The contribution of reliable and clinically significant change methods to evidence-based mental health

TLDR

In mental‑health research, outcomes are measured on continuous scales that overlap normal and abnormal ranges, leading clinicians and researchers to use different language and statistical methods, while clinicians focus on individual change and the NNT approach often relies on arbitrary cut‑offs. The study aims to develop a method that bridges research and clinical practice by integrating individual‑level change assessment with group‑level statistical evidence. Jacobson et al.’s reliable and clinically significant change (RCSC) method quantifies individual change relative to sample distributions and can be applied to any continuous clinical scale. The RCSC concept rests on two individual‑level questions that determine whether change is reliable and clinically significant.

Abstract

Where outcomes are unequivocal (life or death; being able to walk v being paralysed) clinicians, researchers, and patients find it easy to speak the same language in evaluating results. However, in much of mental health work initial states and outcomes of treatments are measured on continuous scales and the distribution of the “normal” often overlaps with the range of the “abnormal.” In this situation, clinicians and researchers often talk different languages about change data, and both are probably poor at conveying their thoughts to patients. Researchers traditionally compare means between groups. Their statistical methods, using distributions of the scores before and after treatment to suggest whether change is a sampling artefact or a chance finding, have been known for many years.1 By contrast, clinicians are more often concerned with changes in particular individuals they are treating and often dichotomise outcome as “success” or “failure.” The number needed to treat (NNT) method of presenting results has gone some way to bridge this gap but often uses arbitrary criteria on which to dichotomise change into “success” and “failure.” A typical example is the criterion of a 50% drop on the Hamilton Depression Rating Scale score. A method bridging these approaches would assist the translation of research results into clinical practice. Jacobson et al proposed a method of determining reliable and clinically significant change (RCSC) that summarises changes at the level of the individual in the context of observed changes for the whole sample.2, 3–5 Their methods are applicable, in one form or another, to the measurement of change on any continuous scale for any clinical problem, although they have been reported primarily in the psychotherapy research literature. The broad concept of reliable and clinically significant change rests on 2 questions being addressed at the level of each …