Abstract
The Concerns With Diagnostic Overshadowing Scale (CDOS) is a standardized psychometric self-report instrument developed by Danielle Fahmi and Alexander J. Mussap (2025) designed to operationalize and quantify the phenomenon of diagnostic overshadowing (DO) from the perspective of patients and informal carers. Diagnostic overshadowing represents a critical clinical and systemic healthcare failure wherein new, emergent, or co-occurring physical health symptoms are erroneously misattributed, dismissed, minimized, or downplayed as manifestations of a pre-existing psychiatric disorder, neurodevelopmental delay, cognitive impairment, or behavioral condition. The CDOS comprises 24 self-report items evaluated on a 5-point Likert-type frequency scale ranging from 1 (Never) to 5 (Always). Psychometric development originated from a 37-item preliminary pool grounded in systematic qualitative reviews and expert patient feedback, refined through rigorous factor analytic protocols across three independent international clinical cohorts residing in Australia, the United States, the United Kingdom, and Canada.
The scale captures three distinct multidimensional domains: CDOS-Experienced (17 items capturing direct interpersonal and systemic healthcare bias, medical dismissal, and treatment withholding), CDOS-Internalised (4 items assessing cognitive ambiguity and self-doubt regarding symptom etiology), and CDOS-Concealment (3 items measuring protective non-disclosure behaviors toward medical personnel). The instrument demonstrates robust internal consistency (Cronbach’s α = .95 for Experienced, .92 for Internalised, and .84 for Concealment). One-year test-retest reliability demonstrated temporal stability for CDOS-Experienced (r = .79), with moderate to lower stability for Concealment (r = .62) and Internalised (r = .40). Structural equation modeling and path analyses establish sound construct, convergent, and discriminant validity, demonstrating that experienced diagnostic overshadowing fully mediates the relationship between objective healthcare delays and persistent medical distrust. The CDOS provides researchers, clinicians, and health policy analysts with a psychometrically validated measure to investigate clinical diagnostic bias, health disparities, and healthcare avoidance among individuals with psychiatric and neurodivergent conditions.
Keywords
Diagnostic Overshadowing, Mental Health Stigma, Healthcare Disparities, CDOS, Health Distrust, Medical Bias, Pre-existing Conditions, Symptom Misattribution, Clinical Psychometrics, Help-Seeking Avoidance
Authors
The Concerns With Diagnostic Overshadowing Scale was developed and validated by researchers affiliated with the School of Psychology at Deakin University in Melbourne, Australia:
- Danielle Fahmi, PhD — School of Psychology, Faculty of Health, Deakin University, Melbourne, Victoria, Australia.
- Alexander J. Mussap, PhD — Associate Professor, School of Psychology, Faculty of Health, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia. ORCID: 0000-0003-1290-3680. Corresponding email: [email protected].
Purpose
The primary clinical and empirical purpose of the Concerns With Diagnostic Overshadowing Scale (CDOS) is to provide an objective, reliable, and standardized methodology for measuring the subjective lived experience of diagnostic interference, medical dismissal, and healthcare marginalization resulting from a documented psychiatric or behavioral health diagnosis. Across primary, secondary, and tertiary healthcare systems, individuals carrying psychiatric diagnoses experience significantly shortened life expectancies, excess mortality from preventable somatic conditions (including cardiovascular disease, metabolic syndrome, neoplasms, and respiratory illnesses), and substantially longer diagnostic intervals. Historically, quantitative clinical metrics focused almost exclusively on provider-side implicit bias simulations or medical chart audits, leaving a major psychometric void regarding patient-reported outcome measures (PROMs) that assess how individuals and their primary caregivers navigate, internalize, and respond to diagnostic overshadowing.
The CDOS addresses this systemic oversight by capturing three distinct operational phases of the clinical encounter: the actual external discriminatory actions encountered in medical settings (Experienced), the cognitive contamination wherein patients begin to doubt their own physical bodily sensations (Internalised), and the subsequent strategic behavioral compensations employed to avoid medical stigma (Concealment). By quantifying these constructs, the CDOS serves critical purposes across multiple domains:
- Epidemiological and Health Services Research: Allowing researchers to determine the prevalence, determinants, and longitudinal trajectories of diagnostic overshadowing in diverse clinical populations, including individuals with major depressive disorder, bipolar affective disorder, schizophrenia-spectrum disorders, and neurodevelopmental conditions.
- Investigation of Healthcare Avoidance and Delay: Providing a psychometrically robust mediating variable that explains why patients with mental illness often delay seeking necessary somatic medical care or disengage prematurely from medical follow-ups.
- Quality Improvement and Healthcare System Audits: Serving as a hospital-wide or clinic-wide evaluation tool to benchmark institutional culture, measure patient safety margins, and evaluate systemic interventions targeted at dismantling clinical stereotyping among medical, nursing, and allied health staff.
- Empirical Assessment of Caregiver Burden: Offering a parallel conceptual framework to evaluate how informal carers perceive provider resistance, advocate for their care recipients, and experience systemic friction when navigating fragmented physical and psychiatric health sectors.
Psychological Construct
The CDOS operationalizes diagnostic overshadowing as a complex, multifaceted socio-cognitive and behavioral phenomenon occurring at the intersection of medical delivery systems, social identity threat, and internal psychological processing. Originally coined in intellectual disability literature by Reiss, Levitan, and Szyszko (1982), the construct of diagnostic overshadowing has expanded within health psychology and clinical psychiatry to describe how salient psychiatric diagnoses dominate clinician perception, acting as an all-encompassing cognitive filter that biases clinical reasoning, diagnostic heuristics, and physical symptom triage. The CDOS delineates three primary dimensions:
1. CDOS-Experienced (External Provider and Systemic Invalidation)
The CDOS-Experienced subscale comprises 17 items that capture direct interpersonal, cognitive, and structural invalidation perpetrated by medical practitioners and health systems. This dimension evaluates concrete clinical interactions wherein physical complaints are explicitly attributed to psychological disturbance, patients’ subjective descriptions of physical symptoms are disbelieved or trivialized, and somatic workups are refused or prematurely terminated. Illustrative behavioral indicators include healthcare workers asserting that a patient is “physically fine” despite debilitating symptoms, overt diagnostic labeling, feeling patronized or disrespected, systemic disconnects between mental and physical health networks, and experiencing an acute loss of autonomy and personal agency within medical settings.
2. CDOS-Internalised (Cognitive Ambiguity and Epistemic Injustice)
The CDOS-Internalised subscale consists of 4 items reflecting the deep psychological impact of recurrent healthcare invalidation upon the individual’s metacognitive processing. When healthcare providers repeatedly pathologize physical distress as psychosomatic, somatic symptom manifestation, or hypochondriasis, patients may internalize these diagnostic heuristics. This results in severe epistemic self-doubt, where patients experience difficulty disentangling organic somatic sensations from psychological distress (e.g., wondering if chest pain is cardiac or panic-induced), leading to profound ambivalence, chronic self-blame, and feelings of helplessness regarding bodily integrity.
3. CDOS-Concealment (Protective Information Management)
The CDOS-Concealment subscale comprises 3 items assessing anticipatory coping and protective behavioral strategies aimed at preventing anticipated medical bias. When patients recognize that a psychiatric record impairs equitable medical investigation, they may deliberately omit psychiatric histories, withhold psychoactive medication lists, or actively deceive healthcare professionals regarding their mental health status. Although intended to secure objective physical evaluations, concealment strategies risk severe adverse pharmacological interactions and undermine holistic clinical care.
Theoretical Framework
The theoretical architecture of the Concerns With Diagnostic Overshadowing Scale integrates fundamental paradigms from social psychology, cognitive science, and medical sociology. Three primary theoretical frameworks underpin the scale’s conceptualization:
Dual-Process Theory and Clinical Cognitive Heuristics
Grounded in Kahneman and Tversky’s dual-process model of cognition, clinical decision-making relies extensively on System 1 (rapid, heuristic, associative processing) and System 2 (deliberate, analytical, rule-based reasoning). In high-pressure, time-constrained medical environments (such as emergency departments and busy outpatient clinics), clinicians frequently default to heuristic shortcuts. The presence of a prominent psychiatric label triggers an availability heuristic and an anchoring effect, where clinicians anchor on the psychiatric condition as the default etiology for all newly presenting somatic complaints. The CDOS-Experienced dimension directly measures the consequences of this failure to engage analytical System 2 verification, capturing instances where physical diagnostic paths are aborted due to premature diagnostic closure.
Modified Labeling Theory and Structural Stigma
Drawing from Bruce Link’s Modified Labeling Theory and Erving Goffman’s foundational sociological work on stigma, the CDOS models the trajectory through which societal devaluation becomes internalized and structuralized. When an individual receives a clinical psychiatric label, cultural stereotypes regarding incompetence, irrationality, emotional volatility, or somatic over-reporting are activated. The CDOS evaluates both the structural manifestations of this stigma (such as systemic disconnects and dismissive communication styles) and its internalization into the individual’s self-concept, resulting in demoralization, vulnerability, and social identity threat within healthcare institutions.
Epistemic Injustice in Healthcare Delivery
The philosophical and bioethical framework of epistemic injustice, articulated by Miranda Fricker, provides crucial theoretical grounding for the CDOS. Specifically, individuals with psychiatric diagnoses endure severe testimonial injustice, wherein healthcare providers assign deflated credibility to the patient’s spoken testimony regarding their own bodily sensations. The CDOS-Internalised and CDOS-Experienced subscales measure the subjective and systemic consequences of this epistemic degradation, showing how discrediting patient reports leads directly to medical disenfranchisement, medical mistrust, and systematic diagnostic withholding.
Validity
The psychometric validation of the CDOS by Fahmi and Mussap (2025) involved rigorous empirical testing using multiple analytical frameworks, demonstrating robust content, construct, convergent, and discriminant validity across diverse clinical samples.
Content and Face Validity
Content development originated from an exhaustive systematic review of qualitative literature examining patient-reported medical discrimination, misdiagnosis, and diagnostic overshadowing. An initial item pool of 37 candidate items was generated to reflect the full clinical spectrum of overshadowing phenomena. Content validity was subsequently examined through iterative qualitative cognitive interviewing and structured feedback panels comprising adults with confirmed histories of psychiatric diagnoses who had experienced diagnostic overshadowing in medical settings. Items that exhibited semantic ambiguity, cognitive redundancy, or inadequate construct alignment were systematically revised or eliminated, resulting in a refined set evaluated across three empirical samples.
Construct, Convergent, and Discriminant Validity
Construct validity was established via structural equation modeling (SEM) and multivariate path analyses evaluating the CDOS against validated instruments measuring healthcare-related delays, medical distrust, and institutional disengagement. In evaluating convergent validity, CDOS-Experienced demonstrated strong, statistically significant negative associations with trust in medical practitioners and broader health systems, while exhibiting significant positive associations with healthcare access delays.
Path analyses testing structural models confirmed powerful mediating mechanisms: the CDOS-Experienced dimension fully mediated the relationship between objective healthcare delays and downstream distrust in both medical professionals and healthcare delivery services:
- Path indirect effect: βMedical delays → CDOS Experienced → Trust in professionals = −.44 (p < .001)
- Path indirect effect: βMedical delays → CDOS Experienced → Trust in services = −.42 (p < .001)
Furthermore, the empirical model explained substantial proportions of variance in total trust in healthcare professionals (R² = .56, p < .001) and total trust in healthcare services (R² = .54, p < .001). These robust structural path estimates establish that diagnostic overshadowing is not merely a benign clinical miscommunication, but a primary psychological driver of systemic healthcare alienation.
With respect to discriminant considerations, Fahmi and Mussap observed that while the CDOS-Concealment subscale demonstrated acceptable internal psychometric consistency, it did not exhibit the expected associations with help-seeking delays or distrust metrics. This suggests that concealment acts as a distinct behavioral management strategy that may operate independently of subjective clinical trust or institutional alienation.
Reliability
The Concerns With Diagnostic Overshadowing Scale exhibits strong internal consistency across its dimensional subscales, along with distinct patterns of temporal stability evaluated over longitudinal intervals.
Internal Consistency
In the validation cohorts examined by Fahmi and Mussap (2025), internal consistency was evaluated using Cronbach’s alpha (α), yielding exceptionally high reliability estimates across all identified subscales:
- CDOS-Experienced (17 items): α = .95, indicating outstanding item homogeneity and measurement precision for evaluating overt provider bias and medical neglect.
- CDOS-Internalised (4 items): α = .92, demonstrating excellent internal consistency despite a concise item structure.
- CDOS-Concealment (3 items): α = .84, reflecting high scale reliability for assessing strategic nondisclosure behaviors.
Test-Retest Reliability and Temporal Stability
Longitudinal stability was assessed via Pearson bivariate correlation coefficients (r) across two survey administrations separated by a 1-year follow-up period:
- CDOS-Experienced: r = .79 (p < .01), demonstrating robust test-retest reliability exceeding standard psychometric thresholds (r ≥ .70) and reflecting the stable, enduring nature of traumatic or dismissive medical experiences over time.
- CDOS-Concealment: r = .62 (p < .01), showing moderate temporal stability, indicative of concealment behaviors that fluctuate depending on changes in healthcare providers, clinical settings, or symptom severity.
- CDOS-Internalised: r = .40 (p < .01), demonstrating weaker temporal stability over 12 months. This finding is theoretically congruent with the dynamic nature of illness cognition, somatic symptom perception, and evolving psychological insight, which may shift as physical conditions resolve or stabilize.
Factor Analysis
The latent structural integrity of the CDOS was evaluated using rigorous exploratory and confirmatory factor analytic procedures across split calibration and validation samples.
Exploratory Factor Analysis (EFA)
An initial Principal Component Analysis (PCA) and subsequent Principal Axis Factoring (PAF) were conducted on odd-numbered cases (calibration sample). Sampling adequacy was confirmed by a Kaiser-Meyer-Olkin (KMO) measure of .89, well above the .80 benchmark for psychometric adequacy. Bartlett’s Test of Sphericity reached high statistical significance, χ²(276) = 3602.64, p < .001, confirming sufficient matrix correlation for factor extraction.
Although seven components yielded initial eigenvalues greater than 1.0 (Kaiser-Guttman criterion), visual inspection of Cattell’s scree plot revealed a distinct point of inflection occurring precisely after the third component. Parallel analysis substantiated the three-component extraction. In the final three-factor solution modeled via PAF, the three extracted factors collectively accounted for 60.81% of the total item variance, resulting in the elimination of non-performing items and the establishment of the final 24-item scale.
Confirmatory Factor Analysis (CFA) and Measurement Invariance
Confirmatory Factor Analysis performed on the even-numbered validation sample confirmed the three-factor structure. Model respecification incorporating targeted error covariance modifications yielded excellent global fit indices, confirming structural stability across independent respondent splits.
Multigroup measurement invariance analyses were conducted to evaluate structural equivalence across respondent roles (patients living with a psychological condition vs. informal carers advocating for individuals with a condition):
- Configural Invariance: Supported, establishing that the fundamental three-factor construct structure is conceptualized equivalently across both patients and carers.
- Metric (Weak) Invariance: Supported, confirming that factor loadings are invariant across respondent groups and that the items evaluate the latent constructs with equivalent sensitivity.
- Scalar (Strong) Invariance: Did not meet full invariance criteria due to significantly higher baseline threshold intercepts among patient respondents compared to informal carers on both the CDOS-Experienced and CDOS-Concealment subscales. This indicates that while the underlying psychological dimensions are identical, patients directly experience higher absolute frequencies of healthcare dismissal and nondisclosure than what is observed by third-party caregivers.
Instrument / Measurement Tool
The Concerns With Diagnostic Overshadowing Scale is structured as an interactive or paper-and-pencil self-report psychometric inventory. The technical attributes and clinical scoring protocols are summarized below:
- Instrument Name: Concerns With Diagnostic Overshadowing Scale (CDOS)
- Test Type: Original psychometric inventory / Patient-Reported Outcome Measure (PROM)
- Administration Method: Electronic survey, clinical interview, or self-administered paper questionnaire
- Target Population: Adults aged 18 years and older (including young adults, middle-aged adults, and older adults) carrying a professionally diagnosed mental health or neurodevelopmental condition who have sought medical care for subsequent somatic symptoms, as well as their primary informal carers
- Geographic Validation: Australia, United States, United Kingdom, and Canada
- Total Item Count: 24 substantive items (accompanied by preliminary demographic and clinical profiling items)
- Response Scale: 5-point Likert-type frequency scale:
- 1 = Never
- 2 = Rarely
- 3 = Sometimes
- 4 = Often
- 5 = Always
- Dimensional Subscales and Scoring Rules:
- CDOS-Internalised: Calculated as the mean score of Items 1, 2, 3, and 4 (Range: 1.0 – 5.0). Reflects cognitive confusion, self-doubt, and attributional ambiguity.
- CDOS-Concealment: Calculated as the mean score of Items 5, 6, and 7 (Range: 1.0 – 5.0). Assesses intentional withholding of psychiatric history from healthcare staff.
- CDOS-Experienced: Calculated as the mean score of Items 8 through 24 inclusive (Items 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, and 24; Range: 1.0 – 5.0). Captures external interpersonal dismissal, diagnostic invalidation, systemic neglect, and loss of healthcare autonomy.
- Clinical & Methodological Scoring Note: Higher scores denote greater frequencies of diagnostic overshadowing concerns and experiences. As noted by Fahmi and Mussap (2025), while CDOS-Concealment demonstrates adequate internal reliability, it exhibits weak predictive associations with downstream help-seeking delays and healthcare distrust; researchers and clinicians focused primarily on health outcomes may choose to utilize the CDOS-Experienced subscale independently or analyze the subscales separately rather than computing an unweighted composite global score.
Permissions & Fee and Test Year
The Concerns With Diagnostic Overshadowing Scale was published in 2025 in the American Psychological Association (APA) journal Stigma and Health. The scale is copyright © 2025 by the American Psychological Association and the instrument developers, Danielle Fahmi and Alexander J. Mussap.
- Licensing and Educational Use: The scale is available free of charge for non-commercial academic research, empirical healthcare investigations, and educational teaching purposes.
- Commercial and Clinical Systems Integration: Healthcare organizations, hospital networks, or commercial entities seeking to incorporate the CDOS into proprietary electronic health records (EHR) or commercial diagnostic platforms should contact the corresponding author, Dr. Alexander J. Mussap ([email protected]), or request permissions via APA Rights and Permissions.
References
- 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
- Fricker, M. (2007). Epistemic injustice: Power and the ethics of knowing. Oxford University Press. https://doi.org/10.1093/acprof:oso/9780198237907.001.0001
- Goffman, E. (1963). Stigma: Notes on the management of spoiled identity. Simon & Schuster.
- Kahneman, D. (2011). Thinking, fast and slow. Farrar, Straus and Giroux.
- Link, B. G., Cullen, F. T., Struening, E., Shrout, P. E., & Dohrenwend, B. P. (1989). A modified labeling theory approach to mental disorders: An empirical assessment. American Sociological Review, 54(3), 400–423. https://doi.org/10.2307/2095613
- Reiss, S., Levitan, G. W., & Szyszko, J. (1982). Emotional disturbance and mental retardation: Diagnostic overshadowing. American Journal of Mental Deficiency, 86(6), 567–574.
- Thornicroft, G., Rose, D., & Kassam, A. (2007). Discrimination in health care against people with mental illness. International Review of Psychiatry, 19(2), 113–122. https://doi.org/10.1080/09540260701278937