Predictive value of clinical and MRI parameters for disease progression in multiple sclerosis – a longitudinal retrospective study

Background: Multiple sclerosis (MS) is characterized by a relapsing-remitting or chronic progressive course with accumulation of disability. Clinical and magnetic resonance imaging parameters predicting disability progression are not well defined.

Objective: To identify clinical and MRI factors that can predict the future clinical progression.

Methods: We studied all patients with confirmed MS that had received a brain MRI in our MS clinic from 1999 to 2002 and a clinical follow-up 2 and 4 years later (n=82). Standardized clinical parameters were retrieved from the patient files, primary endpoint was the EDSS after 2 years. At baseline, the mean EDSS was 3.7; 58 patients had a relapsing-remitting MS, 24 a primary or secondary progressive form. Brain MRI was analyzed for the number and distribution of active and inactive lesions and for measures of atrophy: third ventricular width (TVW), bicaudatio ratio (BCR), and brain parenchymal fraction (BPF). TVW and BCR were measured manually from axial T1- and FLAIR-weighted images, BPF (n=55) was calculated semiautomatically from axial T2-weighted scans. All clinical and MRI parameters were defined prior to the identification of patients from the database. To build a composite score, block-wise multiple regression analysis was used.

Results: We found weak to moderate correlations between MRI parameters of inflammation and clinical outcome parameters. Total number (0.27; p<0.05) and the number of infratentorial lesions (0.31; p<0.01) significantly correlated with the EDSS after 2 years. Brain MRI parameters of atrophy correlated moderately with future disability. A significant relationship with the EDSS was found for TVW (0.40; p<0.001), BCR (0.42; p<0.001), and BPF (-0.49; p<0.001). Clinical parameters at baseline generally had a moderate to high correlation with the EDSS after 2 years with a significant correlation of baseline EDSS (0.87; p<0.001/0.68), walking distance (-0.73; p<0.001), age (0.45; p<0.001), and duration of disease (0.52; p<0.001). Similar correlations were found for most parameters with the EDSS after 4 years.

Conclusion: Both, clinical and MRI parameters obtained during routine work-up were useful to predict further disability in this population of MS patients. EDSS and walking distance at baseline had the highest predictive value, followed by duration of disease, age, measures of atrophy and number of infratentorial lesions. The identified parameters have to be validated in a prospective study.