Concerns With Diagnostic Overshadowing Scale (CDOS)
Measures the experience of diagnostic overshadowing, where physical symptoms are misattributed to a pre-existing mental health condition.
Scale Development & Technical Details
Scale Overview
The Concerns With Diagnostic Overshadowing Scale (CDOS) was developed by Danielle Fahmi, Alexander J. Mussap (2025). It is designed to measure Diagnostic Overshadowing. The scale is intended for use with Adults with pre-existing mental health conditions and their carers.
Scale Structure
This instrument consists of 24 items organized into 3 factors/subscales: CDOS-Internalised, CDOS-Concealment, CDOS-Experienced.
| Factor / Subscale | Items | N |
|---|---|---|
| CDOS-Internalised | 1,2,3,4 | 4 |
| CDOS-Concealment | 5,6,7 | 3 |
| CDOS-Experienced | 8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24 | 17 |
Response Format
Respondents rate each item using a custom response format.
Response anchors: 1 = Never, 2 = Rarely, 3 = Sometimes, 4 = Often, 5 = Always.
Scoring
Items are scored by subscale, with each subscale sum representing a distinct dimension.
Total scores range from 1 to 5. Interpretation guidelines:
- Subscale scores are calculated as the mean of their respective items, ranging from 1 (lowest frequency) to 5 (highest frequency).: 1 – 5
Psychometric Properties
Internal Consistency: The scale has demonstrated good to excellent internal consistency with reported Cronbach’s alpha values of CDOS-Experienced: alpha = .95; CDOS-Concealment: alpha = .84; CDOS-Internalised: alpha = .92.
Administration
The scale is self-administered and typically takes approximately 5 minutes to complete. It can be administered individually or in group settings. No special training is required for administration.