RESUMEN
BACKGROUND AND OBJECTIVE: This study aimed to assess the value of cerebrospinal fluid (CSF) findings for predicting conversion to clinically definite multiple sclerosis (CDMS). METHODS: From a database of 447 patients with a first demyelinating event, the records of 208 patients less than 51 years old who had baseline magnetic resonance imaging (MRI) and CSF examinations and a follow-up of at least 1 year were included. A multivariable Cox model was used to assess the short-term risk of CDMS according to baseline CSF findings after adjustment for prognostic factors (including brain MRI) and to provide a simple classification for predicting CDMS. RESULTS: During a median follow-up of 3.5 years, 141 (67.8%) patients converted to CDMS. In multivariate analysis, younger age (hazard ratio [HR]: 1.44 [95% CI 1.02-2.01]), spatial dissemination on brain MRI (HR: 2.07 [95% CI 1.47-2.91]) and more than 4 WBC/mm³ in CSF (HR: 1.44 [95% CI 1.03-2.02]) were independently associated with CDMS. The Cox score obtained from these three predictors enabled patients to be divided into three groups with significant increased risks of CDMS at 1, 2 and 3 years; groups were classified as high-risk (64.7%, 77.4%, 96.1%), intermediate-risk (33.3%, 51.5%, 61.5%), and low-risk (11.1%, 18.3%, 40.3%). CONCLUSIONS: Age at onset, spatial dissemination on brain MRI and CSF white blood cell count are independently associated with short-term conversion to CDMS. The three proposed risk group classifications could be a useful tool to select patients for early therapeutic intervention.