Standard clinical significance classifications are based on movement between the "dysfunctional" and "functional" distributions; however, this dichotomy ignores heterogeneity within the "dysfunctional" population. Based on the methodology described by Tingey, Lambert, Burlingame, and Hansen (1996), the present study sought to present a 3-distribution clinical significance model for the 21-item version of the Depression Anxiety Stress Scales (DASS-21; P. F. Lovibond & Lovibond, 1995) using data from a normative sample (n = 2,914), an outpatient sample (n = 1,000), and an inpatient sample (n = 3,964). DASS-21 scores were collected at pre- and post-treatment for both clinical samples, and patients were classified into 1 of 5 categories based on whether they had made a reliable change and whether they had moved into a different functional range. Evidence supported the validity of the 3-distribution model for the DASS-21, since inpatients who were classified as making a clinically significant change showed lower symptom severity, higher perceived quality of life, and higher clinician-rated functioning than those who did not make a clinically significant change. Importantly, results suggest that the new category of recovering is an intermediate point between recovered and making no clinically significant change. Inpatients and outpatients have different treatment goals and therefore use of the concept of clinical significance needs to acknowledge differences in what constitutes a meaningful change.

Outcome studies report the percentage of clinically significant outcomes; however, the reliability of these classifications is unclear. The current study explored the extent to which inconsistencies arise in classifying patient outcomes using five clinical significance calculation methods and three outcome measures. Adult inpatients (N = 2,676) treated for depression completed the three outcome measures pre-and post-treatment. Their outcomes were classified as recovered, improved, unchanged, or deteriorated using selected clinical significance calculation methods and outcome measures. The choice of outcome measure used in calculating clinical significance had a greater impact on the classification than the choice of clinical significance calculation method. Guidelines for reporting recovery rates are presented to ensure that appropriate conclusions are drawn.

BackgroundReporting of the clinical significance of observed changes is recommended when publishing mental health treatment outcome studies and is increasingly used in routine outcomes monitoring systems. Since recovery rates vary with the method chosen, we investigated the validity of classifications of clinically significant change when the Jacobson-Truax method and the Hageman-Arrindell method were used.MethodsOf 718 inpatients who completed the Depression Anxiety Stress Scales (DASS-21) and Quality of Life Enjoyment and Satisfaction Questionnaire at admission and discharge to a psychiatric clinic, 355 were invited (and 119 agreed) to complete the questionnaires and the Recovery Assessment Scale six weeks post discharge.ResultsBoth the JT and HA methods showed comparably good validity when referenced against the other indices. Clinically significant change on the DASS-21 was related to a greater consumer-based sense of recovery, greater perceived quality of life, and fewer readmissions to hospital within 28 days of discharge.ConclusionsSince there was found to be no advantage to using one method over another when recovery is of interest, the simpler JT method is recommended for routine usage.