Subthreshold symptom: ideas of reference

Abstract

Introduction: Recent emphasis on a symptom dimension and continuum approach in understanding psychosis calls for more refined descriptions of common psychotic symptoms. Ideas of reference (IOR) are one of the most common symptoms in psychosis. We developed a rating scale for characterizing IOR on a continuum from subthreshold to clinically evident, and describe the phenomenological findings in stable patients with early psychosis.Method: The Interview Scale for Ideas of Reference (ISIOR) was developed from experiential account of patients and validated in a pilot study. A total of 137 consecutive outpatients were interviewed using ISIOR by trained raters. They were also assessed using the Liebowitz Social Anxiety Scale (LSAS), as well as PANSS, SAPS, SANS, CDSS and SUMD by their psychia-trists. Subject also completed the SPQ.Results: IOR was found in 31.4% of patients using ISIOR, compared with 23.4% by clinicians using SAPS and 60.6% by patients using SPQ. In remit-ted patients defined using PANSS criteria, IOR was found in 18% (19/106). In this subgroup, the most common subthreshold IOR experience was being laughed at/talked about (42%). Patients with IOR were 3.8 times more likely to be socially anxious (95% CI, 1.78–8.23, p < 0.01).Conclusion: Subthreshold IOR can be detected using a semistructured interview scale. A proportion of remitted patients had subthreshold IOR despite otherwise adequate disease control. The increased risk of social anxiety in patients with IOR should be noted, and the relationship between the two symptoms merits clarification in view of their intervention implication.