Interpreting Change in Scores on Patient-Reported Outcome Instruments.

Interpreting change in scores on patient-reported outcome instruments is a key aspect of instrument development. Without interpretation guidelines, the clinical meaning of significant improvements observed within a treatment group cannot be ascertained. While the field has contemplated this topic for several decades, there remains inconsistency in terminology, methods, and application. Careful selection of methods can result in determining when change is meaningful, but researchers must keep an open mind to the methods that best fit their study and instrument. In many cases, anchor-based methods are appropriate, but the statistical model that evaluates them should be defensible (eg, linear regression, repeated-measures modeling, logistic regression). Sometimes, researchers must entertain the use of novel methods that may be more appropriate for their planned studies and instrument (eg, standard setting, exit interviews, conjoint analysis). The selection of the method is best supported by clear, transparent communication with the regulatory agency to ensure that the method can support its goals.