Delayed diagnosis of multiple sclerosis in a low prevalence country.

: Early diagnosis and treatment of multiple sclerosis (MS) is crucial to avoid future disability. The factors that influence diagnostic delay in low prevalence settings have been poorly studied.: To evaluate the factors associated with a delayed diagnosis of MS after the symptomatic onset.: Clinical records of confirmed MS patients were reviewed. Diagnostic delay was calculated by subtracting the date of onset from the date of diagnosis and categorized as early and delayed, when below and above than 1 year. Logistic regression was performed to evaluate the likelihood of a delayed diagnosis according to age at first symptom, gender, type of the first symptom, progressive vs relapsing onset, diagnostic criteria prevailing at the time of symptom onset, comorbidities, and family history of MS.: Data of 525 (95.6%) from a cohort of 549 patients were analyzed. About 69.1% were women. The mean age was 43.2 years. About 86.3% had relapsing-remitting MS. The mean overall diagnostic delay was 3.07 years. About 45.7% of the patients had a delayed diagnosis, and it was dependent on the symptom and the diagnostic criteria prevailing at the onset. Multivariate logistic regression showed onset during the Schumacher (OR = 10.03 [95%CI 1.30-77.1], p = 0.027) and Poser (OR = 4.26 [95%CI 1.25-15.15], p = 0.021) years were associated with delayed MS diagnosis.: MS onset before the McDonald diagnostic criteria era is associated with delayed diagnosis.