Vancouver Obsessive Compulsive Inventory (VOCI)

Abstract

The Vancouver Obsessional Compulsive Inventory (VOCI) is a 55-item, self-report psychometric instrument designed to assess the heterogeneous symptoms and underlying cognitive structure of Obsessive-Compulsive Disorder (OCD). It measures a broad range of obsessions, compulsions, avoidance behaviors, and personality characteristics theoretically linked to the disorder.

Developed as an updated revision of the Maudsley Obsessional Compulsive Inventory-Revised (MOCI-R), the VOCI utilizes a 5-point Likert-type scale for scoring and is highly valuable for tracking symptom severity and change over time in clinical and research settings. The structure provides a total score and six distinct subscale scores, offering a detailed profile of the individual’s OCD presentation.

Keywords

Obsessive-Compulsive Disorder, Psychometrics, VOCI, Obsessions, Compulsions, Checking, Contamination, Hoarding, Indecisiveness, Just Right, Self-Report Scale.

Authors

D.S. Thordarson, A.S. Radomsky, S. Rachman, R. Shafran, C.N. Sawchuk, A.R. Hakstian

Purpose

The primary purpose of the VOCI is to provide a comprehensive, multidimensional self-report measure for quantifying the severity and specific symptomatic dimensions of OCD. It moves beyond simple symptom counts to evaluate the underlying cognitive and behavioral patterns typical of the disorder, including complex features like indecisiveness and the need for symmetry.

The scale is particularly useful for clinical applications, such as differential diagnosis and tracking symptom fluctuation in response to pharmacological or psychological treatment. In research, the VOCI aids in understanding the factor structure and phenotypic heterogeneity of OCD, aligning with modern dimensional models of psychopathology.

Construct

The VOCI measures the construct of Obsessive-Compulsive symptomatology, conceptualized not merely as a unitary disorder but as a collection of clinically relevant dimensions. These dimensions encompass both recurring obsessive thoughts and repetitive compulsive behaviors, as well as associated cognitive features that contribute to functional impairment.

The instrument operationalizes the core components of OCD through six specific, empirically derived dimensions, which correspond to distinct clusters of symptoms:

• Contamination: Fear of germs, dirt, or bodily fluids, often leading to excessive washing or cleaning rituals.
• Checking: Repetitive behaviors aimed at preventing perceived harm or danger (e.g., checking locks, appliances).
• Obsessions: Intrusive, unwanted thoughts or images, often aggressive, sexual, or religious in nature.
• Hoarding: Difficulty discarding possessions, regardless of their actual value.
• Just Right: The compulsive need for things to feel “right,” perfect, or symmetrical, often manifesting as slow completion of tasks or ritualized routines.
• Indecisiveness: Chronic difficulty or anxiety related to making decisions, even minor ones, often leading to avoidance or prolonged deliberation.

Validity

The validity of the VOCI was rigorously established using a known-groups design, comparing scores from individuals diagnosed with OCD (n=88) against clinical controls (depression or anxiety, n=60), community adults (n=39), and a student sample (n=200). This methodology aimed to demonstrate the scale’s ability to discriminate between clinical and non-clinical populations.

Results of the study, utilizing the Dunnett method of multiple comparisons, confirmed strong discriminant validity. The OCD sample scored significantly higher than all comparison groups on the VOCI total score, as well as on the Contamination, Checking, Just Right, and Indecisiveness subscales. Furthermore, subsequent t-test analyses confirmed the known-groups validity for the Contamination, Checking, Obsessions, and Hoarding subscales, supporting the instrument’s capacity to differentiate between various symptom dimensions relevant to OCD subtypes.

Reliability

The VOCI exhibits high levels of internal consistency across its dimensions and demonstrates excellent test-retest reliability within clinical populations. Specifically, for the OCD sample, test-retest coefficients remained high—at 0.9 or above—when measured over a 47-day interval, indicating strong temporal stability for clinical symptom measurement.

However, reliability findings varied significantly across samples. While the measure proved highly stable for clinical groups, test-retest reliability observed in the non-clinical student sample was notably lower (0.5 to 0.6). This suggests that the VOCI is most reliable and consistent when applied to individuals exhibiting clinically significant levels of obsessive-compulsive symptoms.

Factor Analysis

The development of the VOCI was rooted in a critical evaluation and subsequent modification of the factor structure derived from its predecessor, the Maudsley Obsessional Compulsive Inventory-Revised (MOCI-R). The authors undertook this modification to produce a self-report measure with greater internal consistency and clarity of factor loading, better reflecting modern dimensional models of OCD phenomenology.

The resulting VOCI structure yielded six distinct subscales: Contamination, Checking, Obsessions, Hoarding, Just Right, and Indecisiveness. This six-factor model demonstrated high internal consistency and strong factor loadings, confirming its utility in capturing the key symptom dimensions recognized within the obsessive-compulsive and related disorders spectrum.

Instrument

Test Type: Self-Report Inventory (Psychometric Scale)

Format: 55 items rated on a 5-point Likert-type scale (0=Not at all to 4=Very much)

Language Available: English (Original)

Population Group: Clinical and Non-Clinical Adults

Age Group: Adults

Population Details: Validated across clinical OCD samples, anxiety/depressed clinical controls, community adults, and university students.

Test Methodology: Total raw scores range from 0 to 220. Interpretation relies on both the total score and six specific subscale scores. Results are often presented in terms of percentile ranks compared to established normative groups (OCD, anxious/depressed, community adults, and students).

Keywords

Obsessive-Compulsive, Clinical Assessment, Self-Report, Psychopathology, Anxiety, Compulsive Checking, Contamination, Symmetry, Dimensional Model.

Authors

Author ORCID Identifier: N/A

Affiliation Email addresses: N/A

Correspondence Address: N/A

Permissions & Fee and Test Year

The VOCI was published in 2004. As an academic instrument published in a peer-reviewed journal (Behaviour Research & Therapy), permissions for clinical or academic use are typically governed by the original authors and the publisher (Elsevier). Users should consult the lead author or the journal for formal licensing agreements.

Test Year: 2004

Reference’s

• Thordarson, D.S., Radomsky, A.S., Rachman, S., Shafran, R., Sawchuk, C.N., Hakstian, A.R. (2004). The Vancouver Obsessional Compulsive Inventory (VOCI). Behaviour Research & Therapy, 42(11), 1289-1314.

Items of the Vancouver Obsessional Compulsive Inventory (VOCI)

Instructions:

Below are statements that may or may not apply to you. Please tap “Not at all”, “A little”, “Some”, “Much”, or “Very much” to indicate how much each question applies to you.

How much is each of the following statements true of you?

	Not at all	A little	Some	Much	Very much
I feel compelled to check letters over and over before mailing them.	0	1	2	3	4
I am often upset by my unwanted thoughts of using a sharp weapon.	0	1	2	3	4
I feel very dirty after touching money.	0	1	2	3	4
I find it very difficult to make even trivial decisions.	0	1	2	3	4
I feel compelled to be absolutely perfect.	0	1	2	3	4
I repeatedly experience the same unwanted thought or image about an accident.	0	1	2	3	4
I repeatedly check and recheck things like taps and switches after turning them off.	0	1	2	3	4
I use an excessive amount of disinfectants to keep my home or myself safe from germs.	0	1	2	3	4
I often feel compelled to memorize trivial things (e.g., license plate numbers, instructions on labels)	0	1	2	3	4
I have trouble carrying out normal household activities because my home is so cluttered with things I have collected.	0	1	2	3	4
After I have decided something, I usually worry about my decision for a long time.	0	1	2	3	4
I find that almost every day I am upset by unpleasant thoughts that come into my mind against my will.	0	1	2	3	4
I spend far too much time washing my hands.	0	1	2	3	4
I often have trouble getting things done because I try to do everything exactly right.	0	1	2	3	4
Touching the bottom of my shoes makes me very anxious.	0	1	2	3	4
I am often upset by my unwanted thoughts or images of sexual acts.	0	1	2	3	4

	Not at all	A little	Some	Much	Very much
I become very anxious when I have to make even a minor decision.	0	1	2	3	4
I feel compelled to follow a very strict routine when doing ordinary things.	0	1	2	3	4
I feel upset if my furniture or other possessions are not always in exactly the same position.	0	1	2	3	4
I repeatedly check that my doors or windows are locked, even though I try to resist the urge to do so.	0	1	2	3	4
I find it very difficult to touch garbage or garbage bins.	0	1	2	3	4
I become very tense or upset when I think about throwing anything away.	0	1	2	3	4
I am excessively concerned about germs and disease.	0	1	2	3	4
I am often very late because I can’t get through ordinary tasks on time.	0	1	2	3	4
I avoid using public telephones because of possible contamination.	0	1	2	3	4
I am embarrassed to invite people to my home because it is full of piles of worthless things I have saved.	0	1	2	3	4
I repeatedly experience the same upsetting thought or image about death.	0	1	2	3	4
I am often upset by unwanted thoughts or images of blurting out obscenities or insults in public.	0	1	2	3	4
I worry far too much that I might upset other people.	0	1	2	3	4
I am often frightened by unwanted urges to drive or run into oncoming traffic.	0	1	2	3	4
I almost always count when doing a routine task.	0	1	2	3	4
I feel very contaminated if I touch an animal.	0	1	2	3	4
One of my major problems is repeated checking.	0	1	2	3	4
I often experience upsetting and unwanted thoughts about losing control.	0	1	2	3	4
I find it almost impossible to decide what to keep and what to throw away.	0	1	2	3	4
I am strongly compelled to count things.	0	1	2	3	4
I repeatedly check that my stove is turned off, even though I resist the urge to do so.	0	1	2	3	4

	Not at all	A little	Some	Much	Very much
I get very upset if I can’t complete my bedtime routine in exactly the same way every night.	0	1	2	3	4
I am very afraid of having even slight contact with bodily secretions (blood, urine, sweat, etc.).	0	1	2	3	4
I am often very upset by my unwanted impulses to harm other people.	0	1	2	3	4
I spend a lot of time every day checking things over and over again.	0	1	2	3	4
I have great trouble throwing anything away because I am very afraid of being wasteful.	0	1	2	3	4
I frequently have to check things like switches, faucets, appliances, and doors several times.	0	1	2	3	4
One of my major problems is that I am excessively concerned about cleanliness.	0	1	2	3	4
I feel compelled to keep far too many things like old magazines, newspapers, and receipts because I am afraid I might need them in the future.	0	1	2	3	4
I repeatedly experience upsetting and unacceptable thoughts of a religious nature.	0	1	2	3	4
I tend to get behind in my work because I repeat the same thing over and over again.	0	1	2	3	4
I try to put off making decisions because I’m so afraid of making a mistake.	0	1	2	3	4
I often experience upsetting and unwanted thoughts about illness.	0	1	2	3	4
I am afraid to use even well kept public toilets because I am so concerned about germs.	0	1	2	3	4
Although I try to resist, I feel compelled to collect a large quantity of things I never actually use.	0	1	2	3	4
I repeatedly experience upsetting and unwanted immoral thoughts.	0	1	2	3	4
One of my major problems is that I pay far too much attention to detail.	0	1	2	3	4
I am often upset by unwanted urges to harm myself.	0	1	2	3	4
I spend far too long getting ready to leave home each day because I have to do everything exactly right.	0	1	2	3	4