Reference values for the Body Image Concern Inventory (BICI), the Whitely Index (WI), and the Checklist Individual Strength (CIS-20R): The Leiden Routine Outcome Monitoring Study.

The Body Image Concern Inventory (BICI), the Whitely Index (WI), and the Checklist Individual Strength (CIS-20R) are three questionnaires often incorporated in routine outcome monitoring (ROM). Respectively, they assess symptom severity in patients with body dysmorphic disorder, hypochondriasis, and chronic fatigue syndrome. We aimed to generate reference values for a healthy population and for a population of patients fulfilling diagnostic criteria for at least one of BDD, hypochondriasis, and CFS, treated in specialized mental health care.The healthy ROM reference-group (n=648) was recruited through general practitioners. These subjects were matched for age and sex with the ROM patient-group (n=823). To define limits (i.e., cut-off-values) for one-sided reference intervals (5th percentile [P5] for ROM patient-group and 95th percentile [P95] for ROM reference-group) the outermost 5% of observations were used. Discriminative powers were evaluated by receiver operating characteristics (ROC) analysesCut-off-values (P95 ROM reference-group) were 55 for the BICI, 6 for the WI, and 92 for the CIS-20R. These values differed for men and women, being mostly higher for women. The discriminative power of all three somatoform questionnaires was very high.Substantial non-response and limited generalizability.For the BICI, WI, and CIS-20R a comprehensive set of reference values was obtained. The reference values may support clinical decisions regarding adjusting or terminating therapy, and possible referral.