Padua Inventory – Washington State University Revision (PI-WSUR)

Abstract

The Padua Inventory – Washington State University Revision (PI-WSUR) is a refined and widely employed 39-item self-report instrument designed for the comprehensive measurement of Obsessive-Compulsive Disorder (OCD) symptomatology. Developed by G. L. Burns and his colleagues, the PI-WSUR represents a significant psychometric advancement over the original Padua Inventory (PI), focusing specifically on achieving clearer empirical distinctions among generalized worry, core obsessions, and specific compulsions.

The scale utilizes a 5-point rating system to quantify the degree of distress or impairment caused by symptoms across five empirically derived dimensions. This factor-analytically grounded approach allows clinicians and researchers to generate a detailed, multidimensional profile of an individual’s obsessive-compulsive presentation, enhancing diagnostic specificity and treatment planning.

Keywords

Padua Inventory, PI-WSUR, OCD, Obsessions, Compulsions, Checking, Contamination, Washing, Self-report measure, Psychopathology, Factor Analysis.

Authors

G. Leonard Burns, S. Keortge, G. Formea, L. G. Sternberger.

Purpose

The primary purpose of the PI-WSUR is to facilitate a detailed, multidimensional assessment of obsessive-compulsive symptomatology that addresses the heterogeneity inherent in the disorder. By employing rigorous factor analysis, the revision aimed to surpass the limitations of earlier scales by clearly delineating the specific content and nature of symptoms, thereby allowing for the identification of five distinct, empirically supported subtypes of OCD presentation.

This instrument serves a dual function: it is valuable for clinical differential diagnosis by separating genuine obsessions and compulsions from generalized anxiety or worry, and it is crucial for research, enabling precise measurement of treatment outcomes and providing empirical support for the dimensional model of the disorder.

Construct

The PI-WSUR measures the psychological construct of obsessive-compulsive disorder symptoms. This construct is defined by the presence of recurrent, intrusive thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) executed to reduce associated distress or prevent a perceived catastrophic event. The scale’s structure is built upon five empirically derived subscales, which reflect the modern understanding of the dimensional nature of OCD.

These five factors represent distinct symptom dimensions widely recognized in the literature on OCD phenomenology, providing granularity that a single total score cannot achieve:

• Contamination Obsessions and Washing Compulsions
• Dressing/Grooming Compulsions
• Checking Compulsions
• Obsessional Thoughts of Harm to Self/Others
• Obsessional Impulses to Harm Self/Others

Validity

The PI-WSUR exhibits strong psychometric validity, which is primarily substantiated by the rigorous factor analysis undertaken during its development. Specifically, the scale demonstrates robust construct validity, confirming its ability to accurately measure and differentiate the five hypothesized symptom factors, which are theoretically distinct components within the broader spectrum of OCD.

Furthermore, studies have documented high convergent validity, evidenced by significant correlations between the PI-WSUR’s total score and subscale scores and those derived from gold-standard measures of OCD severity, such as the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). The instrument also successfully achieved its objective of adequate discriminant validity by effectively distinguishing core obsessive-compulsive symptoms from related constructs like generalized anxiety and depressive symptoms.

Reliability

The reliability of the PI-WSUR is consistently reported as high across diverse research and clinical settings. A key strength is the high level of internal consistency, typically quantified using Cronbach’s alpha, which has been observed not only for the total scale score but critically, for each of the five distinct subscales. This statistical evidence confirms that the items within each factor are coherently measuring a singular, consistent underlying psychological dimension.

While specific test-retest reliability statistics are dependent on the context and interval of measurement, the PI-WSUR is generally recognized as a stable metric. This stability makes it a reliable tool for assessing chronic or static obsessive-compulsive symptom patterns over time, ensuring its utility for both baseline clinical assessment and subsequent outcome measurement in longitudinal studies and clinical trials.

Factor Analysis

The development of the PI-WSUR was fundamentally driven by advanced factor analytic techniques applied to refine the structure of the original Padua Inventory. These studies consistently yielded and supported a clear, stable five-factor structure, providing strong empirical confirmation for the dimensional model of OCD symptoms.

This five-factor model is essential for nuanced clinical practice and research, as it moves beyond a single, undifferentiated score. It allows for precise differentiation between specific obsessional content (e.g., fears of contamination versus intrusive thoughts of harm) and corresponding compulsive behaviors (e.g., washing rituals versus checking rituals). The resulting factors provide distinct clinical profiles, significantly enhancing the scale’s diagnostic and descriptive utility.

Instrument

Test Type: Self-report questionnaire / Psychometric scale

Format: 39 items rated on a 5-point Likert scale.

Language Available: English (Original), translated versions exist for research use.

Population Group: Clinical and Non-clinical populations.

Age Group: Typically utilized with adolescents and adults.

Population Details: Primarily used in samples exhibiting or suspected of exhibiting obsessive-compulsive symptomatology, as well as in general population screenings for subclinical OC traits.

Test Methodology: Respondents rate the statements based on the degree of disturbance the thought or behavior creates, using a scale ranging from 0 to 4:

• 0 = Not at all
• 1 = A little
• 2 = Quite a lot
• 3 = A lot
• 4 = Very much

Keywords

Contamination, Checking compulsions, Harm obsessions, Dressing compulsions, Psychometrics, Self-assessment, PI-WSUR.

Authors

Author ORCID Identifier: N/A (Information not provided in source)

Affiliation Email addresses: N/A (Information not provided in source)

Correspondence Address: G. Leonard Burns, Department of Psychology, Washington State University, Pullman, WA 99164-4820.

Permissions & Fee and Test Year

The PI-WSUR was first published and made available in its revised, 39-item format in 1995.

For information regarding current usage fees, licensing, and explicit permissions necessary for commercial or large-scale clinical application, interested parties are advised to contact the corresponding author, G. Leonard Burns, or the Department of Psychology at Washington State University.

The original PDF of the scale instrument can be downloaded here: http://www.psychologie.tu-dresden.de/i2/klinische/mitarbeiter/materialien/pd-wsur.pdf

Reference’s

1. Burns, G.L. (1995). Padua Inventory-Washington State University Revision. Pullman, WA: Author. (Available from G. Leonard Burns, Department of Psychology, Washington State University, Pullman, WA 99164-4820)
2. Burns, G.L., Keortge, S., Formea, G., & Sternberger, L.G. (1996). Revision of the Padua Inventory of obsessive compulsive disorder symptoms: Distinctions between worry, obsessions, and compulsions. Behavior Research and Therapy, 34, 163-173.
3. Additional resources concerning the scale’s use and properties are available here (PDF link): http://ses.library.usyd.edu.au/bitstream/2123/4026/1/j-swinbourne-thesis.pdf
4. Further psychometric validation information can be found via the following NCBI link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3395932/
5. Additional related material (PDF link): http://www.sid.ir/fa/VEWSSID/J_pdf/68113894501.pdf

Items of the Padua Inventory – Washington State University Revision (PI-WSUR)

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

The following statements refer to thoughts and behaviors which may occur to everyone in everyday life. For each statement, choose the reply which best seems to fit you and the degree of disturbance which such thoughts or behaviors may create. Rate your replies as follows:

0= Not at all, 1= A little, 2= Quite a lot, 3= A lot, 4=Very much

1. I feel my hands are dirty when I touch money
2. I think even slight contact with bodily secretions (perspiration, saliva, urine, etc.) may contaminate my clothes or somehow harm me
3. I find it difficult to touch an object when I know it has been touched by strangers or by certain people
4. I find it difficult to touch garbage or dirty things
5. I avoid using public toilets because I am afraid of disease and contamination
6. I avoid using public telephones because I am afraid of contagion and disease
7. I wash my hands more often and longer than necessary
8. I sometimes have to wash or clean myself simply because I think I may be dirty or ‘contaminated’
9. If I touch something I think is ‘contaminated’ I immediately have to wash or clean myself
10. If an animal touches me I feel dirty and immediately have to wash myself or change my clothing..
11. I feel obliged to follow a particular order in dressing, undressing and washing myself
12. Before going to sleep I have to do certain things in a certain order
13. Before going to bed I have to hang up or fold my clothes in a special way
14. I have to do things several times before I think they are properly done
15. I tend to keep on checking things more often than necessary
16. I check and re-check gas and water taps and light switches after turning them off
17. I return home to check doors, windows, drawers, etc. to make sure they are properly shut
18. I keep on checking forms, documents, cheques in detail to make sure I have filled them in correctly
19. I keep on going back to see that matches, cigarettes, etc. are properly extinguished.
20. When I handle money I count and recount it several times
21. I check letters carefully many times before posting them
22. Sometimes I am not sure I have done things which in fact I know I have done
23. When I read, I have the impression I have missed something important and must go back and re-read the passage at least two or three times
24. I imagine catastrophic consequences as a result of absentmindedness or minor errors which I make
25. I think or worry at length about having hurt someone without knowing it.
26. When I hear about a disaster, I think somehow it is my fault
27. I sometimes worry at length for no reason that I have hurt myself or have some disease
28. I get upset or worried at the sight of knives, daggers, and other pointed objects.
29. When I hear about suicide or crime, I am upset for a long time and find it difficult to stop thinking about it
30. I invent useless worries about germs and disease
31. When I look down from a bridge or a very high window, I feel an impulse to throw myself into space
32. When I see a train approaching, I sometimes think I could throw myself under it’s wheels
33. At certain moments, I am tempted to tear my clothes off in public
34. While driving I sometimes feel an impulse to drive the car into someone or something..
35. Seeing weapons excites me and makes me think violent thoughts
36. I sometimes feel the need to break or damage things for no reason
37. I sometimes have an impulse to steal other people’s belongings, even if they are of no use to me…
38. I am sometimes almost irresistibly tempted to steal something from the supermarket
39. I sometimes have an impulse to hurt defenseless children or animals.