Abstract
The ICD‐11 includes a new definition of adjustment disorder (AjD). The present study aimed to examine interrater reliability, internal consistency, and construct validity of a new diagnostic interview module to assess ICD‐11 AjD. Data from two studies that used a standardized diagnostic interview assessment (i.e., DIA‐X/M‐CIDI and updated DIA‐X‐5) were used. For interrater reliability, agreement indicators (i.e., κ) were calculated using data from the DIA‐X‐5 test–retest study (N = 60). To examine internal consistency and construct validity, Cronbach’s alpha values and the Kuder–Richardson correlation coefficient were computed along with confirmatory factor and latent class analyses (LCA), using data from the Zurich Adjustment Disorder Study (N = 330). Interrater reliability analyses found an adjusted kappa of 0.807 for the ICD‐11 AjD diagnosis. Few items from the impairment criterion of the diagnostic algorithm performed poorly. The internal consistency was acceptable, Cronbach’s αs = .43–.80; the lower‐bound estimate resulted from the two‐item preoccupation symptom pattern. However, both items were significantly associated, OR = 3.14, 95% CI [1.97, 4.99]. Regarding LCA results, a two‐class model was favored. We found that 94.3% of all ICD‐11 AjD cases belonged to Class 2, OR = 23.69, 95% CI [7.15, 79.54], which was associated with subjectively rated distress, OR = 2.18, 95% CI [1.57, 3.02], and the external measure of the Brief Symptom Inventory global severity index, OR = 2.18, 95% CI [1.57, 3.02]. Overall, the new AjD interview module provided a reliable, valid assessment of the ICD‐11 diagnosis; confirmation by other studies is needed.