Development and Psychometric Properties of the

Dimensional Obsessive-Compulsive Scale (DOCS)

Jonathan S. Abramowitz, PhDUniversity of North Carolina at Chapel Hill

Collaborators

• Brett Deacon• Bunmi Olatunji• Michael Wheaton• Noah Berman• Diane Losardo• Kiara Timpano

• 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

• 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

• 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

• MeasuresGroup DOCS OCI-R YBOCS BDI BAI DASS SIAS

OCD X X X X X X

OAD X X X X X

Students X X X X

Results: Exploratory Factor Analysis with Half of the Student Sample

Results: Confirmatory Factor Analyses

• Goodness-of-fit parameters indicated that the student and clinical data fit the four-factor structure very well.

Goodness-of-fit index

Group RMSEA SRMR TLI CFI

Students .059 .042 .99 .96

OCD + OAD .089 .044 .99 .98

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 OCD vs. OAD

Diff in AUC = .06; Z = 4.68, p < .01 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