title: Beta-blocker use and risk of symptomatic bradyarrhythmias: a hospital-based case-control study.
abstract: OBJECTIVE
  To investigate the risk factors of symptomatic bradyarrhythmias in relation to β-blockers use.
  
  
  METHODS
  A hospital-based case-control study [228 patients: 108 with symptomatic bradyarrhythmias (cases) and 120 controls] was conducted in Sultanah Aminah Hospital, Malaysia between January 2011 and January 2014.
  
  
  RESULTS
  The mean age was 61.1 ± 13.3 years with a majority of men (68.9%). Cases were likely than control to be older, hypertensive, lower body mass index and concomitant use of rate-controlling drugs (such as digoxin, verapamil, diltiazem, ivabradine or amiodarone). Significantly higher level of serum potassium, urea, creatinine and lower level of estimated glomerular filtration rate (eGFR) were observed among cases as compared to controls. On univariate analysis among patients on β-blockers, older age (crude OR: 1.07; 95% CI: 1.03-1.11,P= 0.000), hypertension (crude OR: 5.6; 95% CI: 1.51-20.72,P= 0.010), lower sodium (crude OR: 0.04; 95% CI: 0.81-0.99,P= 0.036), higher potassium (crude OR: 2.36; 95% CI: 1.31-4.26,P= 0.004) and higher urea (crude OR: 1.23; 95% CI: 1.11-1.38,P= 0.000) were associated with increased risk of symptomatic bradyarrhythmias; eGFR was inversely and significantly associated with symptomatic bradyarrhythmias in both 'β-blockers' (crude OR: 0.97; 95% CI: 0.96-0.98,P= 0.000) and 'non-β-blockers' (crude OR: 0.99; 95% CI: 0.97-0.99,P= 0.023) arms. However, eGFR was not significantly associated with symptomatic bradyarrhythmias in the final model of both 'β-blockers' (adjusted OR: 0.98; 95% CI: 0.96-0.98,P= 0.103) and 'non-β-blockers' (adjusted OR: 0.99; 95% CI: 0.97-1.01,P= 0.328) arms. Importantly, older age was a significant predictor of symptomatic bradyarrhythmias in the 'β-blockers' as compared to the 'non-β-blockers' arms (adjusted OR: 1.09; 95% CI: 1.03-1.15,P= 0.003vs. adjusted OR: 1.03; 95% CI: 0.98-1.09,P= 0.232, respectively).
  
  
  CONCLUSIONS
  Older age was a significant predictor of symptomatic bradyarrhythmias in patients on β-blockers than those without β-blockers.
authors.affiliation: Clinical School Johor Bahru, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Johor Bahru, Johor, Malaysia; Department of Cardiology, Sultanah Aminah Hospital, Jalan Masjid Abu Bakar, Johor Bahru, Johor, Malaysia.
authors.forename: Hou Tee
authors.initials: HT
authors.lastname: Lu
authors.affiliation: Department of Cardiology, Sultanah Aminah Hospital, Jalan Masjid Abu Bakar, Johor Bahru, Johor, Malaysia.
authors.forename: Jiyen
authors.initials: J
authors.lastname: Kam
authors.affiliation: Clinical School Johor Bahru, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Johor Bahru, Johor, Malaysia.
authors.forename: Rusli Bin
authors.initials: RB
authors.lastname: Nordin
authors.affiliation: Department of Electrophysiology, Institut Jantung Negara, Jalan Tun Razak, Kuala Lumpur, Malaysia.
authors.forename: Surinder Kaur
authors.initials: SK
authors.lastname: Khelae
authors.affiliation: Department of Pharmacy, Sultanah Aminah Hospital, Jalan Masjid Abu Bakar, Johor Bahru, Johor, Malaysia.
authors.forename: Jing Mein
authors.initials: JM
authors.lastname: Wang
authors.affiliation: Department of Cardiology, Sultanah Aminah Hospital, Jalan Masjid Abu Bakar, Johor Bahru, Johor, Malaysia.
authors.forename: Chun Ngok
authors.initials: CN
authors.lastname: Choy
authors.affiliation: Department of Cardiology, Sultanah Aminah Hospital, Jalan Masjid Abu Bakar, Johor Bahru, Johor, Malaysia.
authors.forename: Chuey Yan
authors.initials: CY
authors.lastname: Lee
keywords: Adverse drug reaction; Beta-blocker; Bradyarrhythmias; Case-control