The International Journal of Neuropsychopharmacology

Trends and Perspectives

Treatment non-response in OCD: methodological issues and operational definitions

Stefano Pallanti a1a2c1, Eric Hollander a1, Carol Bienstock a1, Lorrin Koran a3, James Leckman a4, Donatella Marazziti a5, Michele Pato a6, Dan Stein a7, Joseph Zohar a8 and International Treatment Refractory OCD Consortium
a1 Mount Sinai School of Medicine, New York, NY, USA
a2 Institute of Neuroscience, Florence, Italy
a3 Stanford University Medical Center, Stanford, CA, USA
a4 Yale University Child Study Center, New Haven, CT, USA
a5 University of Pisa, Italy
a6 State University of New York at Buffalo, USA
a7 University of Stellenbosch MRC Research Unit on Anxiety Disorders, Capetown, South Africa
a8 Chaim Sheba Medical Center, Ramat Gan, Israel


While controlled trials with SRIs have demonstrated a selective efficacy in obsessive–compulsive disorder (OCD), up to 40–60% of patients do not have a satisfactory outcome. Non-response to treatment in OCD is associated with serious social disability. There are a large number of non-responsive patients, and they are difficult to cluster due to ambiguities in the diagnostic criteria, possibility of subtypes, and a high rate of comorbidity. Moreover, the findings of current studies of so-called ‘non-responsive’ cases are currently non-generalizable because of the lack of an operational definition of non-response. The result has been that a cumulative body of data on a reasonably homogeneous sample of non-responders has not been developed. The aims of this paper are to clarify some of the obstacles in defining stages of response and levels of non-response and, through a comprehensive analysis, to propose a systematic nosology for this rather common condition. Better characterization of which patients respond and do not respond to various treatments will enable more accurate clustering of patients, and help facilitate multi-site data collection for future research trials.

(Received July 9 2001)
(Reviewed November 12 2001)
(Revised January 9 2002)
(Accepted January 22 2002)

Key Words: OCD; refractory OCD; resistant OCD; treatment non-response; treatment response.

c1 Address for correspondence: Dr S. Pallanti, Istituto di Neuroscienze, Viale Ugo Bassi 1, Florence, Italy 50137. Tel.: +39 (055) 587-889 Fax : +39 (055) 581-051 E-mail: