title: Incidence and risk estimate of drug-induced agranulocytosis in Hong Kong Chinese. A population-based case-control study.
abstract: OBJECTIVE
  Drug-induced agranulocytosis is a rare but life-threatening adverse drug reaction. Its epidemiology in Chinese is largely unknown. This study aimed to estimate the incidence, mortality, and risk of the drugs associated with agranulocytosis in Hong Kong Chinese.
  
  
  METHODS
  A population-based case-control study was conducted using the Clinical Data Analysis and Reporting System, a database managed by the Hong Kong Hospital Authority. Patients with drug-induced agranulocytosis from 1 January 2004 to 31 December 2013 were identified. World Health Organization causality assessment was used to evaluate the possible drug aetiology of each case. Odd ratios (ORs) of the drug exposure were calculated using exact conditional logistic regression.
  
  
  RESULTS
  A total of 155 cases of drug-induced agranulocytosis were identified. Mean age was 51.4 years, and 95 cases were female. Incidence rate was estimated to be 2.2 cases per million person-years, and the all-cause mortality of patients with drug-induced agranulocytosis was 3.9%. Among the cases, the most common associated drug groups were antithyroid drugs (41.9%), antimicrobials (20%), anticonvulsants (10.3%), and antipsychotics (6.5%). Carbimazole had the highest risk of agranulocytosis (adjusted OR 416.7, 95% confidence interval (CI) 51.5-3372.9) with an incidence of 9.2 (95%CI 6.9-12.1) per 10 000 users and 3.6 (95%CI 2.7-4.8) per 10 000 user-years. Other drugs with significant risk included cephalosporins, clozapine, penicillins, phenytoin, and propyl thiouracil.
  
  
  CONCLUSIONS
  The incidence and mortality in Hong Kong Chinese were relatively low compared to Caucasians. Antithyroid drugs were the most common implicated drug class, and carbimazole had the highest risk of agranulocytosis. Copyright © 2017 John Wiley & Sons, Ltd.
authors.affiliation: Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong.
authors.forename: Chor-Wing
authors.identifier: http://orcid.org/0000-0002-2180-3676
authors.initials: CW
authors.lastname: Sing
authors.affiliation: Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong.|Centre for Paediatric Pharmacy Research, Research Department of Practice and Policy, School of Pharmacy, University College London, London, UK.|The State Key Laboratory of Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Ian C K
authors.initials: IC
authors.lastname: Wong
authors.affiliation: The State Key Laboratory of Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.|Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Bernard M Y
authors.initials: BM
authors.lastname: Cheung
authors.affiliation: Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Johnny C Y
authors.initials: JC
authors.lastname: Chan
authors.affiliation: Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong.
authors.forename: Jody K P
authors.initials: JK
authors.lastname: Chu
authors.affiliation: Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong.|The State Key Laboratory of Pharmaceutical Biotechnology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.|Department of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Cheung
mesh_terms: D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems; D000368:Aged; D000380:Agranulocytosis / Q000139:chemically induced* / Q000453:epidemiology; D044466:Asian People / Q000706:statistics & numerical data*; D016022:Case-Control Studies; D016208:Databases, Factual; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology*; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
keywords: Chinese; adverse drug reaction; agranulocytosis; pharmacoepidemiology