title: Timing of stroke in patients undergoing total hip replacement and matched controls: a nationwide cohort study.
abstract: OBJECTIVE
  Stroke is a potentially fatal complication of total hip replacements (THR). However, timing of stroke in THR patients compared with matched controls and influence of drug use remain unknown. The objective of this study was to determine timing of stroke in patients with THR compared with matched control subjects.
  
  
  METHODS
  A nationwide cohort study was conducted within the Danish registers (1998-2007). Included patients were those with a primary THR in the study period (n=66,583) and were matched by age, sex, and region to three referent subjects without THR or total knee replacements. Time-dependent Cox models were used to derive hazard ratios and were adjusted for disease history and drug use.
  
  
  RESULTS
  A 4.7-fold increased risk of ischemic stroke (adjusted hazard ratio, 4.69; 95% CI, 3.12-7.06), and a 4.4-fold increased risk of hemorrhagic stroke (adjusted hazard ratio, 4.40; 95% CI, 2.01-9.62) were found within 2 weeks following THR, compared with matched controls. The risk remained elevated during the first 6 postoperative weeks for ischemic stroke, and the first 12 weeks for hemorrhagic stroke. Outpatient antiplatelet drug use lowered the 6-week hazard ratios for ischemic stroke by 70%, although not affecting risk of hemorrhagic stroke.
  
  
  CONCLUSIONS
  This study shows, that THR patients have a 4.7-fold increased risk of ischemic stroke, and a 4.4-fold increased risk of hemorrhagic stroke during the first 2 weeks postsurgery. Risk assessment of stroke in individual patients undergoing THR (ie, evaluate other risk factors for stroke) should be considered during the first 6 to 12 weeks.
authors.affiliation: Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Department of Clinical Pharmacy, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.
authors.forename: Arief
authors.initials: A
authors.lastname: Lalmohamed
authors.forename: Peter
authors.initials: P
authors.lastname: Vestergaard
authors.forename: Cyrus
authors.initials: C
authors.lastname: Cooper
authors.forename: Anthonius
authors.initials: A
authors.lastname: de Boer
authors.forename: Hubertus G M
authors.initials: HG
authors.lastname: Leufkens
authors.forename: Tjeerd P
authors.initials: TP
authors.lastname: van Staa
authors.forename: Frank
authors.initials: F
authors.lastname: de Vries
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data*; D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data; D002545:Brain Ischemia / Q000188:drug therapy / Q000453:epidemiology*; D002543:Cerebral Hemorrhage / Q000188:drug therapy / Q000453:epidemiology*; D015331:Cohort Studies; D015897:Comorbidity; D003718:Denmark / Q000453:epidemiology; D004232:Diuretics / Q000627:therapeutic use; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000188:drug therapy / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011619:Psychotropic Drugs / Q000627:therapeutic use; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000188:drug therapy / Q000453:epidemiology*; D013997:Time Factors
chemical_list: D000925:Anticoagulants; D004232:Diuretics; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011619:Psychotropic Drugs