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

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

LIN-CHUNG WOUNG,¹ PAI-HUEI PENG,² CHIH-CHING LIU,^3,4 CHING-YAO TSAI,¹ KAI-CHEN WANG,⁵ WAN-JU LEE,^6,7,8 TSANG-SHAN CHEN⁹ and CHUNG-YI LI^4,10

¹Department of Ophthalmology, Taipei City Hospital, National Taiwan University, Taipei, Taiwan
²Department of Ophthalmology, Shin-Kong Wu Ho-Su Memorial Hospital, School of Medicine, Catholic Fu-Jen University, Taipei, Taiwan
³Health Promotion Administration, Ministry of Health and Welfare, New Taipei City, Taiwan
⁴Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
⁵Department of Neurology, Cheng-Hsin General Hospital, Taipei, Taiwan
⁶Department of Ophthalmology, National Cheng Kung University Hospital, Tainan, Taiwan
⁷Institute of Clinical Pharmacy and Pharmaceutical Science, College of Medicine, National Cheng Kung University, Tainan, Taiwan
⁸Deran Eye Clinic, Tainan, Taiwan
⁹Department of Neurology, Sin-Lau Hospital, the Presbyterian Church in Taiwan, Tainan, Taiwan
¹⁰Department of Public Health, China Medical University, Taichung, Taiwan

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.

keywords —— cohort studies; incidence rate; multiple sclerosis; optic neuritis; relative hazard

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Tohoku J. Exp. Med., 2013, 231, 171-177

Correspondence: Tsang-Shan Chen, Department of Neurology, Sin-Lau Hospital, the Presbyterian Church in Taiwan, Eastgate Rd. Sec 1, Tainan 70142, Taiwan.

e-mail: tschern@gmail.com