Further validation of the IDAS: Evidence of convergent, discriminant, criterion, and incremental validity.

Abstract

We explicated the validity of the Inventory of Depression and Anxiety Symptoms (IDAS; Watson et al., 2007) in two samples (306 college students, and 605 psychiatric patients). The IDAS scales showed strong convergent validity in relation to parallel interview-based scores on the Clinician Rating version of the IDAS (IDAS-CR); the mean convergent correlations were .51 and .62 in the student and patient samples, respectively. With the exception of Well-Being, the scales also consistently demonstrated significant discriminant validity. Furthermore, the scales displayed substantial criterion validity in relation to DSM-IV mood and anxiety disorder diagnoses in the patient sample. We identified particularly clear and strong associations between (for a recent review, see Joiner, Walker, Pettit, Perez, & Cukrowicz, 2005). At the same time, however, the accumulating research also has exposed some limitations of these instruments, thereby establishing the need for alternative measures (Joiner et al., 2005). Watson et al. (2007) created the Inventory of Depression and Anxiety Symptoms (IDAS) to complement these traditional measures and to address their limitations.The IDAS differs from these older instruments in two basic ways. First, these traditional measures originally were created to yield a single overall index of symptom severity. These total scores are valuable in many contexts; nevertheless, this focus on global dysfunction ignores the heterogeneous and multidimensional nature of depressive symptoms, and it hampers the identification of meaningful subtypes (Ingram & Siegle, 2002;Joiner et al., 2005). In contrast, the IDAS was specifically designed to contain multiple scales assessing specific symptoms of depression (e.g., insomnia, suicidality, appetite loss).Second, extensive evidence has established that these depression measures are very strongly associated with symptoms of anxiety (e.g., Clark & Watson, 1991;Mineka, Watson, & Clark, 1998;Watson, 2005). Consequently, the original IDAS item pool contained a broad range of anxiety-related symptoms. The inclusion of these items facilitated the development of depression scales with good discriminant validity, and also eventually led to the creation of complementary anxiety scales (e.g., social anxiety, panic). Development and Preliminary Validation of the IDAS Further Validation of the IDAS 4 Development of the IDASAn initial pool of 180 items was subjected to a series of analyses in a large undergraduate sample (see Watson et al., 2007, Study 1); this yielded a revised pool of 169 items. Next, this revised set of items was administered to large samples of college students, psychiatric patients, and community adults (Watson et al., 2007, Study 2). Data from these three samples were subjected to separate series of principal factor analyses. Ten specific content factors emerged in all three samples and were used to create corresponding scales. Five of these scales represent specific symptoms of major depression: Insomnia, Lassitude (which includes items refle...

The Mediating Role of Repetitive Negative Thinking in Relationship Between Negative Perfectionism and Severity of Anxiety Symptoms

“…The current study focused on symptoms of psychopathology related to traumatic stress including general depression, suicidality, panic, posttraumatic stress and well-being subscales, experienced in the past two-weeks. The IDAS demonstrated strong internal consistency, test-retest reliability, and good convergent and discriminant validity with respect to formal diagnostic and self-report symptom mea- sub-scale scores were good to excellent (Cronbach's alpha = 0.79 to 0.93), consistent with the past works (24). The alpha coefficient of this scale was 0.95.…”

Anxiety measures validated in perinatal populations: A systematic review

“…Internal consistency ranged from 0.74 (suicidality) to 0.91 (general depression). The IDAS remains to be validated against a clinical interview in perinatal populations but has shown strong correlations in a psychiatric sample particularly between SCID diagnoses of panic disorder and IDAS Panic, posttraumatic stress disorder and IDAS Traumatic Intrusions, and social anxiety disorder and IDAS Social Anxiety (Watson et al, 2008). However, GAD correlated most strongly with IDAS General Depression and Dysphoria, and OCD diagnoses did not show differentially high correlations with any IDAS subscales.…”

Smoking-Related Correlates of Depressive Symptom Dimensions in Treatment-Seeking Smokers

“…First, the analyses are correlational, which precludes interpretations regarding the causal or temporal features of the relations demonstrated herein. Second, although the IDAS identifies empirically overlapping symptoms within each dimension (Watson et al, 2008), some symptoms are phenomenologically varied within a dimension. For example, the dysphoria scale has items assessing anhedonia, concentration difficulties, and sadness, which, despite demonstrating empirical cohesion, may represent distinct depressive phenotypes (Hasler, Drevets, Manji, & Charney, 2004).…”

“…The dysphoria scale contains items reflecting most of the DSM-IV major depression criteria (anhedonia ["I had little interest in my usual hobbies or activities"]; depressed mood ["I felt depressed"]; psychomotor agitation ["I felt fidgety, restless"]; psychomotor retardation ["I talked more slowly than usual"]; worthlessness ["I felt inadequate"]; guilt ["I blamed myself for things"]; diminished concentration ["I had trouble concentrating"]; indecision ["I had trouble making up my mind"]) as well as an item measuring worry ("I found myself worrying all the time"). The IDAS subscales show strong stability and internal consistency as well as excellent convergent, discriminant, criterion, and incremental validity in community, college student, and psychiatric patient samples (Watson et al, 2007(Watson et al, , 2008). …”

“…The BDI-II (Beck & Steer, 1996) is a widely used, well-validated self-report inventory of cognitive, affective, and neurovegetative depressive symptoms experienced in the past two weeks (Steer, Brown, Beck, & Sanderson, 2001). For comparative purposes, we also created a dysphoria symptoms subscale within the BDI-II, which was the sum of BDI-II items corresponding to comparable items on IDAS dysphoria scale (#1 "sadness," #8 "self-criticalness," #11 "agitation," #12 "loss of interest," #13 "indecision," #14 "worthlessness," #19 "concentration difficulty").…”