Risk of multiple sclerosis after idiopathic optic neuritis in a Pakistani population.
OBJECTIVE
Optic neuritis (ON) is associated with a 38% ten-year risk of developing multiple sclerosis (MS) in Western populations, but the corresponding risk in non-Western populations is unclear. We conducted this study to estimate the risk of progression to MS after an episode of ON in a South Asian population.


METHODS
Two hundred and fifty-three patients with idiopathic ON were identified by reviewing records of visual evoked potentials and chart notes from a single academic center spanning the years 1990-2007. A structured telephone interview was then conducted to identify patients who had subsequently received a diagnosis of MS. The diagnosis was corroborated from chart notes, where possible. Cumulative probability of conversion to MS was calculated using Kaplan-Meier survival analysis.


RESULTS
The five-year risk of developing MS was 14.6% and the ten-year risk was 24%. Patients (N = 218) who had one or more typical demyelinating lesions on baseline brain magnetic resonance imaging (MRI) had a 68% 10-year risk; those with no lesions or non-typical lesions had a 14% risk (p < 0.001). Female gender, recurrent ON, and occurrence of ON in winter months were also associated with increased risk (p < or = 0.001). Severity of ON and likelihood of detecting cerebrospinal fluid (CSF) oligoclonal bands were higher in patients who developed MS.


CONCLUSIONS
Idiopathic ON in Pakistan carries a lower risk of progression to MS compared with Western data. As in Western populations, however, presence of abnormal baseline brain MRI and CSF oligoclonal bands correlate with increased MS risk.
Kazim
Syed Faraz
SF
Section of Neurology, Aga Khan University Hospital, Karachi, Pakistan.
Islam
Muhammad
M
Khan
Mustafa
M
Hameed
Bilal
B
Shafqat
Saad
S
D000328:Adult; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000188:drug therapy / Q000453:epidemiology* / Q000209:etiology* / Q000401:mortality; D009902:Optic Neuritis / Q000150:complications* / Q000453:epidemiology; D010154:Pakistan / Q000453:epidemiology; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D013256:Steroids / Q000627:therapeutic use
D013256:Steroids