CORE-OM Calculator

What is the CORE-OM?

The Clinical Outcomes in Routine Evaluation — Outcome Measure (CORE-OM) is a 34-item self-report questionnaire designed to assess psychological wellbeing, functioning, symptoms, and risk. Developed by Chris Evans, Frank Margison, and Michael Barkham in the United Kingdom, the CORE-OM was designed specifically for routine use in psychological therapy services as a pan-theoretical, pan-diagnostic outcome measure.

Each item is scored from 0 ("Not at all") to 4 ("Most or all of the time"), with higher scores indicating greater distress. The CORE-OM covers four domains: subjective wellbeing (4 items), problems/symptoms (12 items), life functioning (12 items), and risk to self and others (6 items). The instrument provides both a total clinical score and domain-specific scores, offering a comprehensive overview of a person's psychological state.

Development and Validation

The CORE-OM was developed through a rigorous multi-phase process involving item generation from existing measures and clinical expertise, followed by psychometric testing across large clinical and non-clinical samples. The original validation study, published by Evans and colleagues in the British Journal of Psychiatry in 2002, demonstrated strong psychometric properties across multiple UK therapy services.

The instrument showed good internal consistency (Cronbach's alpha ranging from 0.75 to 0.95 across domains), adequate test-retest reliability, and strong convergent validity with established measures including the BDI, BAI, BSI, and IIP-32. Importantly, the CORE-OM demonstrated sensitivity to change, with significant pre-to-post-therapy improvements observed across services.

A key design feature is the inclusion of both high-intensity items (e.g. symptoms of anxiety and depression) and low-intensity items (e.g. general wellbeing and daily functioning), ensuring the instrument discriminates effectively across the full range of psychological distress, from well populations to those in significant difficulty.

How CORE-OM Scoring Works

The CORE-OM uses a five-point response scale for each of its 34 items, anchored over the preceding week:

0 = Not at all 1 = Only occasionally 2 = Sometimes 3 = Often 4 = Most or all of the time

Eight items are positively worded and are reverse-scored so that higher values consistently indicate greater difficulty. The primary clinical score is calculated as the mean of all completed items, multiplied by 10 to give a score between 0 and 40. This mean-based approach allows for valid scoring even when a small number of items are missing (up to 10% omissions are acceptable).

Domain scores can be calculated for each of the four areas: - Wellbeing (W): 4 items - Problems/Symptoms (P): 12 items - Functioning (F): 12 items - Risk (R): 6 items

Published clinical cut-off scores distinguish between clinical and non-clinical populations. A clinical score of 10 or above is commonly used as the threshold suggesting clinically significant levels of distress. A reliable change index of 5 or more points indicates statistically reliable change between administrations.

Clinical Applications

The CORE-OM was designed from the outset for routine clinical use rather than as a research-only instrument. Its broad content coverage makes it suitable as a single outcome measure across diverse therapeutic modalities and presenting problems, without assuming any particular theoretical orientation or diagnostic framework.

Common clinical applications include intake assessment to establish baseline severity, session-by-session or periodic monitoring of progress, end-of-therapy outcome measurement, and service-level audit and evaluation. The risk domain items provide a structured opportunity to identify concerns about self-harm or harm to others, although the CORE-OM is not intended as a risk assessment tool in its own right.

The CORE System includes shorter derivatives: the CORE-10 (a 10-item screening version) and the YP-CORE (a young person's version for ages 11 to 16). These variants extend the system's applicability across different settings and age groups while maintaining compatibility with the full CORE-OM.

CORE-OM in Australian Practice

The CORE-OM is used in Australian psychology, counselling, and psychotherapy services, particularly in settings that value a transdiagnostic approach to outcome measurement. Its broad coverage of wellbeing, symptoms, functioning, and risk makes it well-suited for services that see a wide range of presenting difficulties.

Australian university counselling services, Employee Assistance Programs (EAPs), and community mental health organisations have adopted the CORE-OM as part of routine outcome monitoring. Its availability in multiple languages supports use with Australia's culturally and linguistically diverse population.

The CORE-OM complements disorder-specific measures like the PHQ-9 and GAD-7 by providing a broader picture of psychological health. Some Australian services use the CORE-OM as a global measure alongside targeted instruments for specific symptom domains.

The instrument is managed by the CORE System Trust, which oversees its distribution and licensing. Users should confirm current licensing arrangements with the CORE System Trust for their intended use.