Optic neuritis among National Health Insurance enrollees in Taiwan, 2000-2004.

Background: The objective was to examine the incidence of optic neuritis in Taiwan. A 5-year longitudinal, nationwide, population-based study was conducted. The participants were a random sample of 191,761 subjects, or about 1% of the enrollees in the National Health Insurance program of Taiwan.

Methods: We identified subjects who had at least 1 service claim for ambulatory or inpatient care with a principal diagnosis of optic neuritis between 2000 and 2004. We calculated and statistically analyzed the rates of optic neuritis. The main outcome measures were the incidence rates of optic neuritis.

Results: From 2000 to 2004, the total cumulative incidence was 1.33 per 1,000 (1.00 vs. 1.67 for male vs. female subjects; p < 0.001, chi(2) test). The cumulative incidence rates for the age groups of 0-19, 20-39, 40-59 and >or=60 years were 0.33, 1.05, 2.16 and 2.81 cases per 1,000, respectively. Among the subjects aged 40-59 years, the cumulative incidence was higher in women than in men (p < 0.001, chi(2) test). The incidence density of developing multiple sclerosis after optic neuritis was 0.41% per person-year, and the cumulative incidence of multiple sclerosis after a new diagnosis of optic neuritis was 0.78%.

Conclusions: We believe our study is the first nationwide investigation of the incidence rates of optic neuritis in Taiwan. In our investigation, the cumulative incidence peaked among the subjects aged 40-59 years, especially in women. In Taiwan, patients with optic neuritis have a notably low rate of conversion to multiple sclerosis.