A Nine-Year Population-Based Cohort Study on the Risk of Multiple Sclerosis in Patients with Optic Neuritis

Abstract

Patients with optic neuritis (ON) are at an increased risk of developing multiple sclerosis (MS), an illness that may result in physical dysfunction and short life expectancy. Information on the conversion rate to MS of patients with ON is essential in determining the impact of ON on the incidence of MS. Previous Taiwanese studies on the risk of MS in patients with ON were all hospital based, thereby limiting the generalizability of the findings. We aimed to estimate the risk of MS in patients with ON using a nationally representative sample. A cohort of 2,741 patients who sought outpatient care for ON in 2000 was identified from Taiwan's National Health Insurance claims. The control group consisted of 27,330 age- and sex-matched subjects randomly selected from all beneficiaries in 2000. The person-year approach with Poisson assumption was used to estimate the incidence rate of MS from 2000 to 2008. The relative risk of outpatient visit or hospitalization for MS was estimated using the Cox proportional hazard model. The incidence rates of MS in the ON and control groups were 25.6 and 0.4, respectively, per 10,000 person-years; these values represent a relative risk estimate of 30.84 (95% confidence interval: 14.48 to 65.73) after the potential confounders were considered. Female or younger patients with ON were associated with a significantly elevated risk of developing MS. This study found that Taiwanese patients with ON are at a substantially high relative risk of developing MS. In addition to patients with ON, female and younger people should also receive intensive neurological care to further reduce their risk of developing MS.

Trends in Optic Neuritis Incidence and Prevalence in the UK and Association With Systemic and Neurologic Disease

“…This study finds elevated ON risk among young women, as has been reported previously (female-male ratio between 1.5:1 and 2.5:1) . This finding is possibly driven by strong association with MS in the UK population .…”

A prospective, observational study on conversion of clinically isolated syndrome to multiple sclerosis during 4-year period (MS NEO study) in Taiwan

“…The finding of overall low conversion rate to MS of Taiwanese patients complement the results of the earlier retrospective studies which reveals low risk of MS in Taiwan [2,5]. The variability in conversion rates (ranging between 8.3% to 65%) due to geographic, genetic and ethnic factors, and also due to differences in study design, frequency and duration of follow up, sample size and method of assessment is observed.…”

“…It may or may not be a precursor of multiple sclerosis (MS). The conversion rate from CIS to MS ranges from 30% to 82% [1,2,3,4,5]. None of the studies has prospectively analysed the conversion of CIS to MS in Taiwanese population.…”

“…Numerous prognostic factors for conversion to MS after the first episode of CIS have been identified. Of the epidemiological risk factors, ‘female gender’ and ‘young age’ are predictive of conversion to MS [2–5,8–10]. Long term studies have shown that ‘number and activity of MRI lesions’ and ‘spinal cord abnormalities at the time of presentation’ are strong predictors of conversion to MS [7,11].…”

Multi-database study of multiple sclerosis: identification, validation and description of MS patients in two countries

“…Neurologic conditions, such as optic neuritis, paresthesia, and dizziness, were similarly common prior to the diagnosis of MS, as expected, in both the US and UK. Optic neuritis is often the presenting symptom of MS, and longitudinal studies show that 34–75% of patients presenting with optic neuritis in the UK and US develop MS [ 22 , 23 ] and a relative risk > 30 for MS for Chinese individuals with optic neuritis followed for 9 years [ 24 ]. The prevalences of other symptoms such as treated depression and malaise or fatigue were also similar in the two databases.…”