title: Prevalence of drug resistant epilepsy in adults with epilepsy attending a neurology clinic of a tertiary referral hospital in Singapore.
abstract: OBJECTIVE
  To determine the proportion of population of adult people with epilepsy (PWE) in Singapore, who suffer from drug resistant epilepsy (DRE).
  
  
  METHODS
  All adult PWE who had attended the neurology specialist clinic of a tertiary referral hospital in Singapore were profiled for drug responses according to the definition for DRE as specified by the International League against Epilepsy (ILAE) 2010 consensus. This is a retrospective cohort study. Data collected included demographics, characteristics of seizure and epilepsy, blood biochemistry levels, electroencephalogram and brain imaging findings, and medication histories. The types and dosages of antiepileptic drugs (AEDs) used were retrieved from case notes and checked against pharmacy records. Each patient was counselled upon the diagnosis of epilepsy and taught to maintain a seizure diary. The dates and number of seizures were retrieved from these diaries at each visit. Treatment-related adverse effects were routinely assessed and hence, patients were assumed to not have treatment-related adverse effects when no relevant documentation was encountered.
  
  
  RESULTS
  The prevalence rate of DRE in this clinic was 21.5%, while 40.9% of PWE were drug responsive/seizure free at the point prevalence day (n=557). From multivariate analysis, patients with structural-metabolic aetiology [odds ratio (OR) 1.78, 95% confidence interval (CI) 1.003-3.148], mental retardation [OR 2.51, 95% CI 1.073-5.863], psychiatric illnesses [OR 3.349, 95% CI 1.181-9.501] and pre-treatment seizure frequency of more than once monthly [OR 2.775, 95% CI 1.190-6.469] were found to be more likely to have DRE (p≤0.05). Although the influence of Indian ethnicity on the risk of DRE was only found in the univariate analysis, it warrants investigation in a larger cohort.
  
  
  CONCLUSIONS
  The findings may aid policy makers in designing treatment guidelines and allocating resources around PWE, with careful considerations that at any given time, 1 in 5 PWE have DRE.
authors.affiliation: Department of Pharmacy, National University of Singapore, Singapore.
authors.forename: Sing Teang
authors.initials: ST
authors.lastname: Kong
authors.affiliation: Department of Pharmacy, National University of Singapore, Singapore.
authors.forename: Choon Siang
authors.initials: CS
authors.lastname: Ho
authors.affiliation: Department of Pharmacy, National University of Singapore, Singapore. Electronic address: phahocl@nus.edu.sg.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Ho
authors.affiliation: Department of Neurology, Singapore General Hospital, Singapore; National Neuroscience Institute, Singapore; Duke - National University of Singapore - Graduate Medical School, Singapore. Electronic address: lim.shih.hui@sgh.com.sg.
authors.forename: Shih-Hui
authors.initials: SH
authors.lastname: Lim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000009:adverse effects*; D002648:Child; D004351:Drug Resistance; D004569:Electroencephalography; D004827:Epilepsy / Q000188:drug therapy / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012846:Singapore / Q000453:epidemiology; D062606:Tertiary Care Centers; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D000927:Anticonvulsants
keywords: Adults; Asian; Drug resistant epilepsy; Prevalence; Refractory epilepsy; Singapore