Concerns With Diagnostic Overshadowing Scale (CDOS)

Description

The Concerns With Diagnostic Overshadowing Scale (CDOS; Fahmi & Mussap, 2025) is designed to quantify the experiences of diagnostic overshadowing (DO) in both patients and carers. The development of the CDOS involved the creation of a preliminary draft with 37 items, which was informed by a review of relevant qualitative literature. Feedback was then sought from adults who had experienced DO to refine the items and assess content validity. Psychometric evaluation of the data was conducted using three samples of patients with a psychological condition and adults who reported having experienced DO at some point in their life and their carers residing in Australia, the United States, the United Kingdom, or Canada. Factor analyses identified a final three-factor structure with 24 items. Structural equation modeling provides convergent evidence of construct validity. Results concerning the reliability, validity and measurement invariance were reported.

Purpose

The CDOS serves as a measure of the experience of interference with medical diagnosis or treatment due to a preexisting condition from the patient or carer perspective.

Validity

Structural equation modeling provides convergent evidence of construct validity in relation to measures of health care–related delays and distrust. Consistent with discriminant evidence of construct validity, results of path analyses obtained with the DO experiences model confirm that CDOS experienced fully mediated paths from medical delays to distrust in health care professionals and services, βMedical delays → CDOS → Trust in professionals = −.44; βMedical delays → CDOS → Trust in services = −.42, both significant at p < .001, and explained substantial and significant variance in trust in health care professionals, R² = .56, and services, R² = .54, both significant at p < .001. Content validity was assessed during the item refinement process through feedback from adults who had experienced DO. Test Methodology includes Test Validity; Construct Validity; Content Validity; Convergent Validity; Discriminant Validity; Structural Equation Modeling

Reliability

Internal Consistency: The Cronbach’s alpha coefficients for the factors were: CDOS experienced = .95; CDOS concealment = .84; CDOS internalized = .92.
Test-Retest Reliability: Pearson bivariate correlations between CDOS subscale scores in Surveys 1 and 2, at 1-year follow-up, indicated acceptable test–retest reliability (r > .7) for CDOS experienced, r = .79, p < .01, but weaker test–retest reliability for CDOS concealment, r = .62, p < .01, and CDOS internalized, r = .40, p < .01. Test Methodology includes Test Reliability; Internal Consistency; Test-Retest Reliability

Factor Analysis

Exploratory Factor Analysis: PCA on odd-numbered cases met criteria for sampling adequacy, KMO = .89, and sphericity, Bartlett’s Test of Sphericity at χ2(df = 276) = 3602.64, p < .001. Although 7 components achieved eigenvalues above 1, inspection of the scree plot indicated a point of inflection occurring after the third component. Percent variance explained also tapered off after the third component, and a 3-component solution was also confirmed by the results of parallel analysis. Collectively, the three factors modeled in the PAF explained 60.81% of the variance of the remaining items.
Confirmatory Factor Analysis: CFAs on even-numbered cases included modifications, improving the model fit.
Measurement Invariance: Findings supports configural and metric invariance of the three-factor CDOS model, but poor scalar invariance due to higher baseline levels of CDOS experienced and concealment in patients relative to carers.
Test Methodology includes Factor Analysis; Confirmatory Factor Analysis; Exploratory Factor Analysis; Principal Component Analysis; Measurement Invariance

Test Methodology

Test Validity; Construct Validity; Content Validity; Convergent Validity; Discriminant Validity; Test Reliability; Internal Consistency; Test-Retest Reliability; Factor Analysis; Confirmatory Factor Analysis; Exploratory Factor Analysis; Principal Component Analysis; Measurement Invariance; Structural Equation Modeling. Administration Method: Electronic

Population Details

The scale was developed using samples of patients with a psychological condition and adults who reported having experienced DO at some point in their life and their carers residing in Australia, the United States, the United Kingdom, or Canada.

Age Group

Adulthood (18 yrs & older); Young Adulthood (18-29 yrs); Thirties (30-39 yrs); Middle Age (40-64 yrs); Aged (65 yrs & older)

Population Group

Human; Male; Female; Transgender. Gender Identities Reported: Women; Men; Trans/Nonbinary; Other. Location: Australia; United States; United Kingdom; Canada

Test Type

Original

Instrument Type

Inventory/Questionnaire

Format

A 5-point Likert-type scales anchored between 1 (never) and 5 (always) is used to indicate the frequency with which each instance of DO occurred.

Language Available

English

Keywords

Diagnostic Overshadowing; Preexisting Condition; Treatment Delay; Treatment Interference; Experiences; Concealment; Internalization; Health Care Delivery; Internalization; Medical Diagnosis; Treatment Withholding; Treatment; Treatment Process and Outcome Measures; Lived Experience

Test Year

2025

Author

Fahmi, Danielle; Mussap, Alexander J.

Author Orcid Identifier

Mussap, Alexander J.: http://orcid.org/0000-0003-1290-3680

Affiliation

Fahmi, Danielle: School of Psychology, Deakin University
Mussap, Alexander J.: School of Psychology, Deakin University

Email

Mussap, Alexander J.: [email protected]

Files

No file is Available

Permissions

May use for Research/Teaching

Fee

No

Correspondence Address

Mussap, Alexander J.: Deakin University, School of Psychology, 221 Burwood Highway, Melbourne, Victoria, Australia, 3125, [email protected]

Reference’s

Fahmi, D., & Mussap, A. J. (2025). Development and preliminary investigation of the Concerns With Diagnostic Overshadowing Scale (CDOS). Stigma and Health. Advance online publication. https://doi.org/10.1037/sah0000614

Items of the Concerns With Diagnostic Overshadowing Scale (CDOS)

Concerns with Diagnostic Overshadowing Scale (CDOS)

Instructions: Diagnostic overshadowing occurs when symptoms of a physical illness are dismissed, downplayed, misattributed, or misdiagnosed because of a pre-existing mental health or behavioural health condition (e.g., psychological disorder, neurodevelopmental disorder/delay, cognitive impairment, intellectual disability) that has been professionally diagnosed.

The following statements describe examples of diagnostic overshadowing, including potential self-doubts, concerns about treatment by healthcare professionals, and experiences regarding actual treatment.

Please think about the most prominent example of diagnostic overshadowing you have experienced. If you have more than one diagnosed mental health condition, focus on the one you feel had the greatest impact on your treatment. If diagnostic overshadowing occurred with more than one physical illness, focus on the physical illness most affected. The severity of the physical illness is less important than the fact it occurred after your mental health diagnosis.

Indicate how often each statement applied to you at that time using the scale below. Participation is optional.

Participant Information

Name or description of the diagnosed mental health condition:

Age when you received this diagnosis (in years): __________

Therapies (including medications) received (optional):

Name or description of physical illness:

Age when you first experienced symptoms of this physical illness (in years): __________

The physical illness was diagnosed or treated by (select all that apply):
[ ] General practitioner (doctor, physician, etc)
[ ] Specialist (paediatrician, pathologist, surgeon, etc)
[ ] Allied health professional (nurse, paramedic, etc)
[ ] Other: _________________________________________

Scale Items

Please use the following scale to provide your responses:
1 = Never
2 = Rarely
3 = Sometimes
4 = Often
5 = Always

1. I could not tell whether my symptoms were due to a physical illness or my pre-existing mental health condition. _____

2. I worried that it was my mental illness that was making me physically unwell. _____

3. I had difficulty separating my physical symptoms from my mental health condition. _____

4. I believed that my symptoms were a combination of physical illness and mental illness. _____

5. I avoided mentioning my previous mental health issues to medical practitioners. _____

6. I tried to keep my mental health diagnosis a secret from health professionals. _____

7. I avoided telling doctors that I had previously been treated for a psychological condition. _____

8. I worried that medical staff would not focus on my physical illness. _____

9. Medical staff told me that I was physically OK when I knew that I was not. _____

10. Health professionals seemed to be preoccupied with my pre-existing mental health condition. _____

11. My requests for medical intervention were ignored or dismissed. _____

12. Health professionals did not take my symptoms seriously. _____

13. I did not receive adequate help in managing my physical illness. _____

14. My physical health was ignored by medical practitioners. _____

15. Medical staff diagnosed my symptoms as signs of an underlying mental health condition. _____

16. The doctors did not believe my symptoms were real. _____

17. I was made to feel that the symptoms I experienced were somehow my own fault. _____

18. I felt that I had been labelled as ‘mentally ill’ by medical staff. _____

19. I felt that my independence was compromised by the medical system. _____

20. I felt helpless when it came to my health care. _____

21. There seemed to be a disconnect between the physical health care system and the mental health care system. _____

22. I felt misunderstood by health care professionals. _____

23. I believe that my physical health needs were not met because of my mental health diagnosis. _____

24. The health system did not treat me with respect. _____

Scoring

CDOS-Internalised = mean of items 1-4
CDOS-Concealment = mean of items 5-7
CDOS-Experienced = mean of items 8-24

Note: Despite adequate reliability, the concealment subscale (CDOS-Concealment) does not demonstrate close associations with help-seeking behaviours that should be relevant to diagnostic overshadowing concerns, such as personal delays in seeking healthcare, and trust in healthcare professionals and services. Until this matter is resolved, researchers and clinicians using the CDOS may wish to omit this subscale from their own research or practice.