Clinically Meaningful Change Reconsidered: Introducing Reliable Response

Clinically meaningful change is a key concept in the evaluation of clinical psychological andpsychiatric treatments. While status-based approaches, such as the Reliable Change Index(Jacobson & Truax, 1991), test whether post-treatment scores fall outside the dysfunctionalrange and whether change exceeds random fluctuations due to an imprecise measurementinstrument, they do not account for baseline severity. Response-based approaches (e.g., Leuchtet al., 2009), on the other hand, define improvement as the percentage symptom reduction frombaseline and are therefore clinically intuitive, but they typically ignore measurement error andmay misclassify random fluctuation as true improvement. Therefore, we propose a novelapproach to clinically meaningful change, termed reliable response, which retains the clinicalinterpretability of response while explicitly accounting for measurement error. Using twoillustrative schizophrenia cases based on realistic score distributions of the Positive andNegative Syndrome Scale (PANSS) in dysfunctional clinical populations, we demonstrate thattraditional approaches can yield inconclusive results, whereas the reliable response approachenables evaluations that are both clinically plausible and statistically defensible. We provide auser-friendly tool in the supplement to apply our approach, which we callthe Reliable Response Calculator (RRC). The tool allows users to determine whether observedsymptom improvements represent reliable meaningful responses. Although the RRC ispreconfigured for the PANSS, it can be adapted to other instruments, facilitating application ofthe reliable response approach across a wide range of clinical contexts.