title: Anticoagulant management of atrial fibrillation: the influence of dosing algorithm and recall schedule on time in therapeutic range.
abstract: BACKGROUND
  The quality of anticoagulation management in atrial fibrillation patients is reflected by the concept of time spent in therapeutic range (TTR). In a primary care setting, the implementation of a dose nomogram could help increase the mean TTR among these patients.
  
  
  OBJECTIVE
  This study compares the influence of a dose algorithm with an integrated recall on TTR prior to standard care and after the implementation of the protocol.
  
  
  METHODS
  In a purposive sample of patients with AF, an uncontrolled 'before' and 'after' study design was utilized to measure the effects of the protocol on TTR. Demographic data, TTR levels, frequency of international normalized ratio (INR) within therapeutic range, clinician adherence to dose nomogram and warfarin dose changes were captured from consultations at the anticoagulation clinic.
  
  
  RESULTS
  A total of 152 patients with AF were entered into the final analysis. The increment in mean TTR in the 'after' intervention phase (2.9%) was not statistically significant (57.5-60.4%, P=0.252). The increase in the frequency of INR values within therapeutic range in the 'after' intervention phase was significant (50.0-56.0%, P<0.05) but with a very low effect size (r=0.04).
  
  
  CONCLUSIONS
  The implementation of a dose nomogram has the potential of reducing unnecessary dose changes for minor fluctuations in INR levels. The findings in this study needs to be confirmed in a future study involving other indications for anticoagulation, various regional primary care clinics and a larger population size.
authors.affiliation: Primary Care Research Initiative and Methods Education Department (PRIMED), Seremban Primary Care Clinic, Jalan Rasah, 70300 Seremban, Negeri Sembilan Darul Khusus, Malaysia. yogarabin@gmail.com.
authors.forename: Y
authors.initials: Y
authors.lastname: Swarna Nantha
mesh_terms: D000368:Aged; D000465:Algorithms; D000925:Anticoagulants / Q000008:administration & dosage*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D003661:Decision Support Techniques; D005260:Female; D019983:Guideline Adherence; D006801:Humans; D019934:International Normalized Ratio; D065186:Interrupted Time Series Analysis; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D017410:Practice Guidelines as Topic; D010818:Practice Patterns, Physicians'; D011320:Primary Health Care / Q000379:methods*; D013997:Time Factors; D014859:Warfarin / Q000008:administration & dosage*
chemical_list: D000925:Anticoagulants; D014859:Warfarin
keywords: Atrial fibrillation; TTR; dose nomogram; predictors; primary care; warfarin.