Impact of daily dosing frequency on adherence to chronic medications among nonvalvular atrial fibrillation patients.
BACKGROUND
Multiple daily dosing may be negatively associated with patient medication adherence, but the findings are inconclusive. The objective of this study was to compare adherence rates to once-daily (q.d.) versus twice-daily (b.i.d.) dosing regimen of chronic medications in patients with nonvalvular atrial fibrillation (AF).


METHODS
The authors analyzed the PharMetrics Integrated Claims database from January 1, 2004 to December 31, 2009. Adult patients with continuous insurance coverage, newly initiated on diabetes or hypertension medication, and having at least one AF diagnosis with no valvular heart disease or valve replacement procedures were included. Compliance to q.d. and b.i.d. therapies was calculated in two ways: medication possession ratio (MPR) and proportion of days covered (PDC). Adherence was defined as an MPR or PDC ≥0.8. Multivariate logistic regressions were conducted to compare the probability of adherence between the q.d. and b.i.d. groups adjusting for baseline confounders.


RESULTS
A total of 8,256 q.d. and 2,441 b.i.d. patients were identified. The mean duration of exposure to therapy for q.d. and b.i.d. patients was 447 and 406 days (P < 0.001), respectively. Based on MPR, 75.3% of q.d. and 70.4% of b.i.d. patients were adherent (P < 0.001). For PDC at 12 months, the proportion of adherent patients for the q.d. and b.i.d. groups was 56.5% and 49.6% (P < 0.001), respectively. Adjusted odds ratios (95% CI) of adherence for the q.d. relative to b.i.d. group were 1.26 (1.13, 1.41) based on MPR and 1.23 (1.07, 1.41) based on PDC at 12 months.


CONCLUSIONS
This study demonstrates that nonvalvular AF patients treated with q.d. dosing regimens for chronic medications were associated with approximately a 26% higher likelihood of adherence compared with subjects on b.i.d. regimens.
Groupe d'analyse, Ltée, 1000 rue de la Gauchetière Ouest, Bureau 1200, Montréal, Québec, H3B 4W5, Canada. flaliberte@analysisgroup.com
François
F
Laliberté
Winnie W
WW
Nelson
Patrick
P
Lefebvre
Jeff R
JR
Schein
Jonathan
J
Rondeau-Leclaire
Mei Sheng
MS
Duh
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage; D000959:Antihypertensive Agents / Q000008:administration & dosage; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000188:drug therapy*; D002908:Chronic Disease; D015331:Cohort Studies; D016001:Confidence Intervals; D016208:Databases, Factual; D003920:Diabetes Mellitus / Q000175:diagnosis / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000188:drug therapy*; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D016015:Logistic Models; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011379:Prognosis; D011792:Quebec; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D016896:Treatment Outcome; D016903:Drug Monitoring
D000889:Anti-Arrhythmia Agents; D000959:Antihypertensive Agents; D007004:Hypoglycemic Agents