title: Randomized trial of lottery-based incentives to improve warfarin adherence.
abstract: BACKGROUND
  Poor adherence to medications is a major cause of morbidity and inadequate drug effectiveness. Efforts to improve adherence have typically been either ineffective or too complex to implement in clinical practice. Lottery-based incentive interventions could be a scalable approach to improving adherence.
  
  
  METHODS
  This was a randomized, controlled clinical trial of a daily lottery-based incentive in patients on warfarin stratified by baseline international normalized ratio (INR). The trial randomized 100 patients to either a lottery-based incentive or no lottery intervention. Main outcome was out-of-range INRs.
  
  
  RESULTS
  Over 6 months, the overall percentage of out-of-range INRs did not differ between the 2 arms (mean 23.0% in lottery arm and 25.9% in control arm, adjusted odds ratio [OR] 0.93, 95% CI 0.62-1.41). However, among the a priori subgroup with a baseline INR below therapeutic range, there was a significant reduction in out-of-range INR in the lottery arm versus the control arm (adjusted OR 0.39, 95% CI 0.25-0.62), whereas there was no such effect among those with therapeutic INRs at baseline (adjusted OR 1.26, 95% CI, 0.76-2.09, P value for interaction = .0016). Among those with low INR at baseline, there was a nonsignificant 49% reduction in the odds of nonadherence with the intervention (OR 0.51, 95% CI 0.23-1.14).
  
  
  CONCLUSIONS
  Although a lottery-based intervention was not associated with a significant improvement in anticoagulation control among all study participants, it improved control among an a priori group of patients at higher risk for poor adherence.
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6021, USA. stevek@mail.med.upenn.edu
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Kimmel
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Troxel
authors.forename: George
authors.initials: G
authors.lastname: Loewenstein
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Brensinger
authors.forename: Jane
authors.initials: J
authors.lastname: Jaskowiak
authors.forename: Jalpa A
authors.initials: JA
authors.lastname: Doshi
authors.forename: Mitchell
authors.initials: M
authors.lastname: Laskin
authors.forename: Kevin
authors.initials: K
authors.lastname: Volpp
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D002318:Cardiovascular Diseases / Q000188:drug therapy; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D009042:Motivation; D013923:Thromboembolism / Q000517:prevention & control*; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin