Screening for cognitive dysfunction in multiple sclerosis

M. R. Basso, S. Beason-Hazen, J. Lynn, K. Rammohan and R. A. Bornstein
Department of Psychiatry, Ohio State University Medical Center, Columbus, USA.

BACKGROUND: With the use of comprehensive neuro-psychological assessments, a substantial proportion of patients with multiple sclerosis have been found to have substantial cognitive impairment. Although data generated from comprehensive examinations are useful in making recommendations for treatment interventions and compensatory strategies, the cost of such assessments prohibits their use with all patients. OBJECTIVE: To develop a screening battery to detect cognitive impairment in patients with multiple sclerosis that is sensitive, specific, brief, and cost-effective, and could identify patients who might benefit from a more comprehensive neuropsychological examination. DESIGN: On the basis of a comprehensive neuropsychological assessment battery, the presence of significant cognitive impairment was determined in patients with multiple sclerosis. The screening battery consisted of a subset of tests from the comprehensive battery. Performance on the screening battery was then used to predict presence of cognitive impairment on the comprehensive battery in validation and cross-validation samples. Severity of impairment on the screening battery was also regressed on ratings of functional impairment derived from the Expanded Disability Status Scale. RESULTS: In the validation sample, the screening battery had 100% sensitivity, 80% specificity, and 88.1% overall diagnostic accuracy. In the cross-validation sample, the screening battery had 100% sensitivity, 81.8% specificity, and an overall diagnostic accuracy rate of 90.7%. chi 2 tests showed that the accuracy of the screening battery was significantly better than chance in both samples. Performance on the screening battery also predicted the level of disability ratings on the Expanded Disability Status Scale and functional systems scales. CONCLUSIONS: The screening battery had a high degree of sensitivity, specificity, and diagnostic accuracy, while maintaining a brief administration time and high cost-effectiveness. The screening battery also predicted higher levels of disability and functional impairment as assessed by the Expanded Disability Status Scale, thereby enhancing its clinical utility. Despite its advantages, the findings do not suggest that the screening battery may be an effective substitute for a more detailed examination.