Development and
Psychometric Properties of the
Dimensional Obsessive-Compulsive Scale
(DOCS)
Jonathan S. Abramowitz, PhD
University of North Carolina at Chapel Hill
Collaborators
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Brett Deacon
Bunmi Olatunji
Michael Wheaton
Noah Berman
Diane Losardo
Kiara Timpano
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Patrick McGrath
Bradley Riemann
Thomas Adams
Throstur Bjorgvinsson
Eric Storch
Lisa Hale
Assessment of OCD
• OCD is heterogeneous
• Challenges in assessing OCD symptoms
– Measure a wide range of possible symptoms
– Do so efficiency (as few items as possible)
• Approaches
– Assess only the quintessential obs. and comps.
• PI/PI-R, OCI/OCI-R, MOCI
– Assess the severity of the patient’s main symptoms
• YBOCS/D-YBOCS
Limitations of Existing OCD Measures
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Symptom severity is confounded with breadth
Severity is confounded with popularity of sx
One dimensional assessment of severity
Obsessions assessed separately from rituals
Avoidance?
Hoarding?
We Need New OCD Measures
• Assess the severity of empirically supported symptom
dimensions
– Contamination, responsibility for harm/mistakes,
Unacceptable thoughts, symmetry/incompleteness
• Multiple severity parameters
• Assess avoidance
• Assess severity independent of type or range of
symptoms
• Easy to administer
DOCS
• Four sections (one for each symptom dimension)
– Contamination, responsibility, unacceptable
thoughts, symmetry/incompleteness
• Each section contains
– Examples of obsessions, compulsions, avoidance
– Five severity questions (time, avoidance, distress,
interference, control) rated 0 to 4
• 20 items in all Approximately 5-10 mins. to read
and complete
Study Aims
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Factor structure
Reliability and Validity
Diagnostic accuracy
Treatment sensitivity
Method
• Participants (data collected at 8 sites)
– 315 adults with OCD
– 198 adults with other anxiety disorders (OAD)
– 1,044 unselected undergraduate students
• Measures
Group
DOCS
OCI-R
YBOCS
BDI
BAI
DASS
OCD
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OAD
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Students
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SIAS
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Results: Exploratory Factor Analysis
with Half of the Student Sample
Results: Confirmatory Factor Analyses
Goodness-of-fit index
Group
RMSEA
SRMR
TLI
CFI
Students
.059
.042
.99
.96
OCD + OAD
.089
.044
.99
.98
• Goodness-of-fit parameters indicated that the
student and clinical data fit the four-factor
structure very well.
Correlations among factors showing
weak to moderate relationships
Reliability
• Cronbach’s alpha and
item-total correlation
• Test-retest
Convergent and Discriminant Validity:
DOCS Total Score
Convergent and Discriminant Validity:
DOCS Factors/Subscales
Known-Groups Validity
Diagnostic Accuracy: ROC Analyses
• DOCS total score discriminates:
– OCD patients from nonclinicals (AUC = .86)
– OCD patients from OAD patients (AUC = .77)
• Cutoff scores
– A score of 21 correctly classified 70% of OCD
patients and 70% of OAD patients
– A score of 18 correctly classified 78% of OCD
patients and 78% of students
Diagnostic Accuracy: DOCS vs. OCI-R
OCD vs. Nonclinical
Diff in AUC = .06; Z = 4.68, p < .01
OCD vs. OAD
Diff in AUC = .08; Z = 3.57, p < .01
Sensitivity to Treatment
Conclusions
• The DOCS is a conceptually & psychometrically sound
measure of OC symptoms in patients and nonpatients
– Addresses many of the limitations of existing measures
• Uses
– Baseline assessment of symptom dimensions
– Treatment response (use “main” symptom dimension)
– Measure of psychopathology for research
• Future work
– Test-retest in a clinical (OCD) group
– Child version
– Translations