The CORE-OM was the first outcome measure that I used in my practice. Along with the shorter CORE-10, it remains my measure of choice. In this blog I explore both: how they were developed; what they measure; how you can understand the numbers and where you can find them.
Given that most counsellors and psychotherapists are not trained in the use of outcome measures it is almost inevitable that we should have misconceptions about them and their use. CORE probably suffers more than most in that the CORE measures are part of the wider CORE System, and these tools sit alongside a broader quality evaluation framework for psychological therapy.
In this blog I’ll be focusing on two of the CORE measures that are most commonly used in therapy: the 34 item CORE-OM and the ten item CORE-10. Before that, however, I’ll say a few words on each of the main components of CORE so that it’s clear where the measures sit within the wider system. If you want to skip that and go straight to the detail of the CORE-OM click here.
34 item global/generic distress measure
Scoring range 0 – 4
Covers domains of:
Wellbeing (4 items); Problems and symptoms (12 items); Functioning (12 items) and Risk (6 items)
Includes positively and negatively framed items
Includes high and low-intensity items
Clinical cut-off: 1 (0 – 4 scale); 10 (0 – 40 scale)
Reliable change index (RCI): 0.5 (0 – 4 scale); 5 (0 – 40 scale)
The CORE measures
The CORE measures are measures of psychological distress (more on that later). The CORE-OM is the parent measure for a wider family of derivative measures that meet specific needs in terms of length of measure or client population. These include the CORE-10; CORE-5; CORE-LD (for people with learning disabilities); YP-CORE (for younger clients) and two short forms for use in research or general practice settings.
The CORE System
The CORE measures sit within a wider system designed to aid the evaluation of service quality and outcomes. The main elements of the system are the CORE-OM, and the practitioner completed Therapy Assessment Form (TAF) and End of Therapy Form (EOT). The TAF is designed to support assessment and captures information about the client and their circumstances including key dates; presenting problems and their severity; current and previous use of services; risk and whether or not the client entered into therapy.
The EOT captures post-therapy information that allows data from the client completed CORE-OM to be seen in context. It includes session attendance; therapy model; a review of presenting problem severity and risk and how therapy ended (i.e. planned or unplanned ending)
The CORE quality evaluation framework
In March 2006 Counselling and Psychotherapy Research published a range of CORE related papers. [i] Six of these provided benchmarks (based on NHS primary care provider data) for key indicators of service quality against which individual services could be benchmarked. The benchmarks were: waiting times; outcome measure completion rates; assessment outcomes; congruence between practitioner rated and client indicated risk; therapy ending types and rates of recovery and improvement. Taken together, these indicators form the basis for a simple but robust framework for evaluating the quality of therapy service provision.
You can read more about the development of the CORE System and its philosophy on the CORE System Trust website here
The CORE Outcome Measure (CORE-OM)
What is it?
The CORE-OM is a 34-item global measure of distress. It was developed in the 1990’s in response to a widely perceived need for a short, and free, outcome measure which fulfilled a number of key criteria. These were that it should be:
* Free to use
* Capable of capturing a range of ‘core’ concerns that present in therapy settings, including subjective wellbeing, problems/symptoms, functioning, and risk of harm to self or others
* Sufficiently short to be used in practice settings
* Applicable to both research and practice settings
* Acceptable to service users and practitioners alike
What does it measure?
The 34 items of the CORE-OM capture distress or severity of symptoms across four key domains:
Subjective wellbeing (4 items)
Problems and symptoms (12 items)
Functioning (12 items)
Risk (6 items)
The domain to which each item belongs can be determined (on paper versions of the measure) by the letter to the right of the furthest right box (the OFFICE USE ONLY column). Hence W = Wellbeing; P = Problems and symptoms; F = Functioning; R = Risk. This is illustrated below.
Within each domain (save for wellbeing) there are clusters of items, as follows:
Problems: this domain contains four clusters (Depression, Anxiety, Physical and Trauma)
Functioning: this domain contains three clusters (General, Social and Close)
Risk: this domain contains two clusters (Risk to Self and Risk to others)
The CORE-OM, its domains and symptom clusters also contain both high and low intensity items. As an example, the risk of harm to self cluster contains the low intensity item I have thought it would be better if I were dead and the high intensity item I have made plans to end my life. In assessing risk, therefore, careful attention needs to be paid item scores in the context of whether they are attached to high or low intensity items.
Scoring the measure
The scoring range of the CORE-OM is between 0 and 4, with 4 being the highest level of severity. As can be seen from the image above, some items are positively framed (items 3 and 4). For these items the scoring range is reversed.
The client is guided to consider each statement and how often they have felt like this over the past week. They are asked to then tick the box which corresponds most closely to their experience, using the categories at the top of each column from Not at all to Most or all the time.
Working with paper forms the score for each statement can be written in the adjacent OFFICE USE ONLY box. From here there are three ways of obtaining a meaningful overall score:
Add the scores for all items in the box circled in the image below (Total Scores * All items) to derive a total score between 0 and 136.
Divide the total score by the number of completed items (normally 34) to obtain a mean score between 0 and 4. (E.g. a total score of 56 / 34 will yield a mean score of 1.64). Some practitioners prefer using a simpler 0 – 40 scale where the 1.64 is multiplied by 10 and converted to a whole number i.e. 16.
In the absence of a calculator or better long division skills than I possess, multiply the total score by 3 and divide by 100. This will yield a ‘good enough’ working mean. (E.g. 56 * 3 / 100 = 1.68)
In the same way it is possible to use steps 1 and 2 to obtain total and mean scores for each of the four domains. For a mean score for the wellbeing domain, for example, simply add the four wellbeing items and divide by four.
What do the numbers mean?
A higher score on the CORE measures, domains or individual items indicates a higher level of distress or symptom severity.
The clinical cut-off [ii] for the CORE-OM is 1 (using the 0 – 4 scale), or 10 (using the 10 – 40 scale). This is represented in the image from CORE Net below by the blue dotted line. The image shows the session by session progress of a demonstration client within CORE Net, the online monitoring and tracking system provided by CORE IMS. The client starts with an overall score (solid blue line) of 21, considerably above the dotted blue cut-off at 10. By session six they have improved and are scoring below the cut-off. Red lines represent the risk cut-off and scores.
The reliable change index (RCI) for the CORE-OM is 0.5 (or 5 using the 0 – 40 scale). This is the degree of change required for it to be classed as reliable i.e. change greater than might occur due to chance or measurement error. The client in the chart below has therefore achieved reliable and clinically significant improvement (RCSI).
What is it?
CORE-10 is a ten-item measure of general psychological distress. The ten items are derived directly from the CORE-OM parent measure. It was developed to respond to the need for a brief screening and progress monitoring tool that could be used to track session to session progress.
The aspiration of the developers of CORE-10 was to:
“…enable measurement of depression while retaining coverage of general psychological distress within a measure that could be used easily by practitioners and clients at screening as well as used for ongoing review during the course of therapy.” [iii]
What does it measure?
The criteria for inclusion of items in CORE-10 included that it should contain (from the CORE-OM) two items each for depression and anxiety and one each covering trauma and physical problems; should include high and low intensity items; aim to cover the each of the three functioning clusters (social, general and close); include both positively and negatively framed items and include at least one risk item.
The wellbeing items in the CORE-OM were dropped as they display high correlation with the problem domain items. Items with lower response rates from the CORE-OM were dropped and regression analyses conducted on the remaining items to optimise correlation with the full CORE-OM. The items finally chosen for CORE-10 include:
Problems and symptoms (6 items; 2 anxiety, 2 depression, 1 trauma, 1 physical)
Functioning (3 items; 1 each close, general and social functioning)
Risk (1 item)
Scoring the measure
Scoring the CORE-10 could not be simpler: simply add together the individual item scores to arrive at a total score (between 0 – 40).
Those of you more familiar with using the mean score from the CORE-OM need simply to divide the total score by the number of completed items to determine the mean score. Caution should be exercised where less than nine items are completed, and I’d recommend checking with clients the significance of non-completed items, especially risk. The only risk item in CORE-10 is the high intensity item I have made plans to end my life, and we should not assume that clients will always feel able to complete this item entirely honestly.
Cost, copyright and obtaining the measures
Copyright of all the CORE instruments is held by the CORE System Trust. All have always been free to reproduce on paper provided they were not changed in any way, their reproduction was not for profit and copyright was acknowledged.
Since 2015, organisations are also free to reproduce the instruments in software, as well as on paper, under a Creative Commons Attribution-No Derivatives 4.0 International (CC BY-ND 4.0) licence without payment of any licence fee. Under the terms of this licence the instruments may not be changed in any way.
The measures may be downloaded in PDF format via the CORE IMS website.
[i] Mellor-Clark J (ed). 2006. Special Issue: Developing CORE System benchmarks. Counselling and Psychotherapy Research. March 2006.
[ii] Cut-offs are statistically derived points which differentiate between what are known as clinical and non-clinical populations. In other words, if a client scores above 10 on the CORE-OM, their score is said to be more representative of a clinical population. These population norms, as they are known, exist for any measure that has statistical validity. While their characteristics vary from measure to measure depending on the sampling carried out, they are derived from large samples of a) clients receiving therapy or some kind of mental health intervention, and b) wider population samples.
[iii] Barkham M et al. 2013. The CORE-10: A short measure of psychological distress for routine use in the psychological therapies. Counselling and Psychotherapy Research · March 2013. DOI: 10.1080/14733145.2012.729069
How to choose a therapy outcome measure
Introducing measures into working with clients
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