An examination of the criterion-related validity of varying methods of indexing clinically significant change in posttraumatic stress disorder treatment.

Objective: Clinicians, patients, and researchers need benchmarks to index individual-level clinically significant change (CSC) to guide decision making and inferences about treatment efficacy. Yet, there is no consensus best practice for determining CSC for posttraumatic stress disorder (PTSD) treatments. We examined criterion-related validity of the most common approach-Jacobson and Truax's (J&T; 1991) procedures for indexing CSC. We generated and compared four methods of calculating the J&T indices of CSC (two sets of sample-specific inputs, putatively norm-referenced benchmarks, and a combination of sample-specific and norm-referenced criteria) with respect to their association with a criterion index of quality of life (QoL).

Method: Participants were 91 women Veterans enrolled in a randomized clinical trial for PTSD who completed self-report measures on PTSD symptoms and various domains of QoL and functioning, pre- and posttreatment. For each of the four methods used to calculate CSC, the QoL composite was regressed onto the CSC categories.

Results: All methods explained large variance in change in QoL. Across all methods, participants categorized as unchanged had smaller changes in QoL, compared with those who improved or had probable recovery. The norm-referenced benchmarks accounted for the relatively largest amount of variance in QoL, but categorized the fewest patients as having made CSC.

Conclusions: The J&T methodology for indexing CSC in PTSD symptoms has criterion-related validity, and a norm-referenced benchmark appears to be the most potent. However, the norm-referenced parameters may be overly specific, potentially leading to an underestimate of improvement. Research is needed to test the generalizability of these results. (PsycInfo Database Record (c) 2024 APA, all rights reserved).