Development of a scrupulosity severity scale using the Pennsylvania Inventory of Scrupulosity-Revised

• Scrupulosity may be missed as the primary OCD subtype, interfering with treatment outcome.
• The Pennsylvania Inventory of Scrupulosity-Revised (PIOS-R) has not been evaluated in a clinical sample.
• A CFA revealed that the two-factor structure exhibited a good fit using a sample of residential OCD patients.
• A ROC analysis indicated that a score of 24 could reliably classify patients with significant scrupulosity among this sample.
• These results indicate that the PIOS-R is an appropriate measure for evaluating scrupulosity in patients with severe OCD.

Presently, the only clinically valid assessment of scrupulosity, an OCD subtype, is the Pennsylvania Inventory of Scrupulosity-Revised (PIOS-R; (Olatunji, Abramowitz, Williams, Connolly, & Lohr (2007). Journal of Anxiety Disorders, 21(6), 771–787). To date, no study has evaluated the factor structure and diagnostic utility of this measure in a severe psychiatric sample. A clinical sample of 417 residential OCD patients with and without primary scrupulosity was assessed using the PIOS-R. A confirmatory factor analysis revealed that the previously-observed two-factor PIOS-R structure exhibited a good fit with these data. A receiver-operator characteristic (ROC) analysis indicated that the PIOS-R could reliably classify patients with clinically significant scrupulosity among the residential sample, with a score of 24 (out of 60) indicating the threshold of scrupulosity severity for which targeted treatment is warranted. These results indicate that the PIOS-R is a useful and appropriate measure for use in evaluating scrupulosity in patients with severe OCD.