Clinical Outcomes in Routine Evaluation 10 (CORE-10)

The CORE-10 is valued for its brevity and its utility in tracking changes over time in response to treatment or other interventions, making it suitable for routine outcome monitoring in clinical and non-clinical settings (Barkham et al., 2013). 

The scale is sensitive to experiences of those with depression, anxiety, post traumatic stress disorder and other highly prevalent mental health disorders. The scale also has items related to suicide, social supports and sleep, making it a valuable tool for identifying risks and treatment targets over and above other questionnaires that purely assess symptoms of psychological distress. Moreover, unlike more condition-specific tools, the CORE-10 offers a broad snapshot of psychological well-being, making it useful for screening across a range of mental health concerns.

Scores are presented as a total score ranging from 0 to 40. Higher scores indicate higher levels of general psychological distress, where a score of 11 and above is within the clinically significant range. Questions 2 and 3 are reverse-scored items.

The scale classifies individuals into distinct severity categories based on their total scores, as follows (Connell & Barkham, 2007):

• Healthy (0–5): Scores in this range indicate no or minimal psychological distress, suggesting the individual is functioning well. This range represents the bottom 35% of the population, indicating that these scores, while healthy, are not representative of the majority of people’s typical experience.
• Low Level (6–10): Scores in this range suggest low levels of distress, where some symptoms of anxiety or low mood might be present but do not significantly impair daily functioning. They are unlikely to meet the diagnostic criteria for depression or anxiety.
• Mild (11–14): Scores in this range indicate mild psychological distress of clinical significance, where symptoms are noticeable but unlikely to disrupt daily functioning. People in this range probably meet the criteria for depression, anxiety, or another mental disorder.
• Moderate (15–19): Scores in this range reflect moderate distress, with symptoms that are pronounced and interfere with the individual’s daily functioning. People who score 15 or higher represent the top 10 percent of psychological distress in the population.
• Moderate-to-Severe (20–24): Scores in this range indicate significant psychological distress, where symptoms are likely to interfere with daily functioning and require clinical attention. Less than 2% of community samples score 20 or above, making this level of psychological distress relatively infrequent in the general community, but quite typical in mental health settings.
• Severe (25 and above): Scores in this range indicate severe distress, suggesting a high level of psychological impairment and an urgent need for clinical intervention. People who score in this range almost certainly meet the diagnostic criteria for an anxiety, mood, or other mental disorder.

Percentiles are calculated and provide a useful context for comparing a respondent’s results with a normative community sample. A percentile of 50 represents typical patterns of responding, while higher percentiles represent higher levels of distress-related symptoms. Percentiles of 68 and below corresponding to a raw score of 10, indicate no or minimal distress-related symptoms (Bewick et al., 2008; Connell & Barkham, 2007).

The horizontal graph presents the total score in comparison to individuals from the general population and a clinical population with shaded areas presented around the two middle quartiles (between the 25th and 75th percentile) (Bewick et al., 2008; Connell & Barkham, 2007). The clinical distribution represents individuals seeking counselling for anxiety, depression, and/or interpersonal difficulties. This graph helps contextualise patterns of responding in comparison to the distribution of responses among the normative community and clinical populations.

Scores of 11 and above are indicative of clinically significant psychological distress, and scores of 13 and above likely indicate depression, with a sensitivity and specificity of .92 and .72 respectively (Connell & Barkham, 2007).

When using the CORE-10 to track symptoms over time, a significant change is defined as an increase or decrease of 6 or more points. This criterion is based on the Reliable Change Index. Such changes indicate reliable and significant improvement or deterioration in symptoms (Barkham et al., 2013).

Higher scores on the CORE-10 indicate greater levels of global psychological distress, encompassing symptoms of anxiety and depression (Barkham et al., 2013). Individuals with high psychological distress may experience difficulties managing their mental health, which can affect their ability to function in work, relationships, and social situations (Randall & Bodenmann, 2008; Thorsteinsson et al., 2014). Higher distress levels are associated with lower quality of life and increased risk of mental health deterioration (Noreen et al., 2021).

The CORE-10 was designed as a brief, generic measure to assess psychological distress in routine mental health care. It was derived from the longer CORE-OM (34 items) to meet the need for a quick, easily administrable tool in primary care settings. The items were chosen based on a mix of coverage, statistical analyses, and the importance of representing key domains of distress. These domains included depression, anxiety, trauma, and physical symptoms. Out of the CORE-OM’s 34 items, 10 were selected for their relevance and statistical performance (Barkham et al., 2013).

The factor structure of the CORE-10 has been evaluated in both clinical and normative community samples, consistently demonstrating a unidimensional structure of psychological distress. In a study involving a normative community sample of 548 participants (Mean age = 23.29, SD = 7.29, 84.5% female), recruited through universities and social platforms, a Confirmatory Factor Analysis (CFA) identified a single-factor model for the CORE-10 (Latona et al., 2023). Similarly, in a clinical sample of 892 individuals (aged 17-25) from a mental health service, both Exploratory Factor Analysis (EFA) and CFA provided further support for a unidimensional factor structure (O’Reilly et al., 2015).

Barkham et al. (2012) validated the CORE-10 in primary care patients as well as the general population, finding it had an internal reliability (alpha) of .9. The CORE-10 correlated strongly with the full CORE-OM, with correlation values (r) of .94 in clinical samples and .92 in non-clinical samples (Barkham et al., 2013). The CORE-10 demonstrated strong correlations with several established outcome measures, including the Beck Depression Inventory-II (BDI-II) (r = .77), Symptom Checklist-90-Revised (SCL-90-R) (r = 0.81), Brief Symptom Inventory (BSI) (r = 0.75), Patient Health Questionnaire-9 (PHQ-9) (r = 0.56), and the Beck Anxiety Inventory (BAI) (r = 0.65), reflecting its strong validity across diverse psychological assessments. The divergent validity of the tool is also sound as the correlations with anxiety-focused measures, such as the Generalised Anxiety Disorder Assessment (GAD-7), were lower than with depression-focused measures, reflecting the broader focus of the CORE-10 on general psychological distress (Barkham et al., 2013).

Based on an analysis by Connell and Barkham (2007), it was determined that scores of 11 and above were indicative of clinically significant psychological distress, and scores of 13 and above likely indicated depression, with a sensitivity and specificity of .92 and .72 respectively (Connell & Barkham, 2007). This indicates that the tool accurately identifies 92% of individuals with depression, while correctly classifying 72% of those without the condition. The Reliable Change Index (RCI) for the CORE-10 is 6 points (90% confidence interval), indicating that a score change of 6 or more points is necessary to represent statistically reliable improvement or deterioration (Barkham et al., 2013). The same RCI was also established through the analysis of data from over 2,215 separate episodes of care, measured using the CORE-10 on NovoPsych, between February 2019 and February 2022.

The normative community percentiles were generated by combining two normative samples. The first sample, as reported in the CORE-10 manual (Connell & Barkham, 2007), included a general population sample of 535 individuals (Mean age = 43.4, SD = 15.3, 49% female) with a mean CORE-10 score of 4.7 (SD = 4.8). The second sample comprised 1,129 university students from four UK universities, with a mean age of 21.4 years (SD = 5.1, 74% female). This student sample had a mean CORE-10 score of 8.47 (SD = 6.41) (Bewick et al., 2008). The pooled mean and SD scores computed by NovoPsych from both samples were M = 7.26 (SD = 5.94).

The clinical sample reported in the CORE-10 manual consisted of 1,835 individuals (Mean age 38, SD = 12.6, 72% female) receiving primary care counselling in the UK. This clinical group had a mean score of 19.7 (SD = 7.7) and primarily included clients seeking counselling for anxiety (71%) and/or depression (65%), with 50.9% also reporting interpersonal difficulties (Connell & Barkham, 2007).

Supplementary Material

The percentile table below illustrates how total scores (see Table 1) compare to individuals from the general population and those seeking counselling for anxiety, depression, and interpersonal difficulties (Bewick et al., 2008; Connell & Barkham, 2007). Each score is accompanied by a corresponding percentile, indicating the percentage of individuals who scored the same or lower from the reference group. For instance, a total score of 8 corresponds to the 55th percentile in the normative community sample and the 6th percentile in the clinical sample (Table 1). This score signifies that 55% of the individuals in the general population had a score of 8 or lower, whereas only 6% of people in the clinical population. These graphs provide an understanding of a respondent’s standing relative to the normative community sample and those seeking counselling for anxiety, depression, and interpersonal difficulties.

The normative community percentiles were generated by combining two normative samples. The first sample, as reported in the CORE-10 manual (Connell & Barkham, 2007), included a general population sample of 535 individuals (Mean age =  43.4, SD = 15.3, 49% female) with a mean CORE-10 score of 4.7 (SD = 4.8). The second sample comprised 1,129 university students from four UK universities, with a mean age of 21.4 years (SD = 5.1, 74% female). This student sample had a mean CORE-10 score of 8.47 (SD = 6.41) (Bewick et al., 2008). The pooled mean and SD  scores computed by NovoPsych from both samples were M = 7.26 (SD = 5.94).

The clinical sample reported in the CORE-10 manual consisted of 1,835 individuals (Mean age 38, SD = 12.6, 72% female) receiving primary care counselling in the UK. This clinical group had a mean score of 19.7 (SD = 7.7) and primarily included clients seeking counselling for anxiety (71%) and/or depression (65%), with 50.9% also reporting interpersonal difficulties (Connell & Barkham, 2007).

Note. The CORE-10 is freely accessible to anyone via the Core Systems Trust. You can also assess your patients with the Clinical Outcomes in Routine Evaluation 10 using a NovoPsych account.

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