Rasch analysis of the hospital anxiety and depression scale in patients with chronic fatigue syndrome.
Bartholomew, Emerson J, Medvedev, Oleg N, Petrie, Keith J et al. · Journal of psychosomatic research · 2025 · DOI
Quick Summary
This study tested whether a common questionnaire called the Hospital Anxiety and Depression Scale (HADS) accurately measures anxiety and depression in people with ME/CFS. Researchers analyzed responses from 286 ME/CFS patients and found that the questionnaire works reasonably well, but they discovered that converting the scores into a different format makes the results more precise and reliable for clinical use.
Why It Matters
Accurate measurement of anxiety and depression is crucial for ME/CFS patients since psychological distress is common and needs proper assessment for treatment planning. This study demonstrates that the HADS can be used more reliably in ME/CFS populations when scores are converted to a special interval format, potentially improving clinical decision-making and research consistency.
Observed Findings
Initial Rasch analysis showed suboptimal model fit, requiring modification of the questionnaire subtests
Rasch-converted interval scores yielded higher mean values (M = 22.55, SD = 3.78) than ordinal scores (M = 20.30, SD = 6.87), a statistically significant difference (p < .001)
The revised subtest solution achieved acceptable fit with high reliability (PSI = 0.87) and strict unidimensionality
Converting scores to interval format produced a 45% reduction in measurement error
No differential item functioning was detected across demographic variables
Inferred Conclusions
The HADS demonstrates acceptable measurement properties in CFS populations when properly analyzed and rescored
Ordinal (standard) scoring systematically underestimates the actual level of anxiety and depression being measured
Rasch-converted interval scores should be preferred over traditional ordinal scores for improved precision in clinical and research settings
The HADS remains suitable for continued use in ME/CFS assessment with appropriate conversion methods
Remaining Questions
How do these findings apply to ME/CFS patients across different healthcare systems and countries with varying disease severity?
What This Study Does Not Prove
This study does not prove that the HADS causes or contributes to anxiety and depression in ME/CFS, nor does it establish whether the anxiety/depression measured are primary conditions or secondary responses to chronic illness. The study also does not compare the HADS to other psychological assessment tools or determine which measurement approach is best for all clinical situations.