Predictors of Over-Anticoagulation in Warfarin Users in the UK General Population: A Nested Case-Control Study in a Primary Health Care Database.

BACKGROUND: Many patients on warfarin therapy often present with supratherapeutic international normalized ratio (INR) levels, resulting from the influence of several patient-specific factors, which have been associated with adverse outcomes. OBJECTIVE: This article aims to identify risk factors for over-anticoagulation (INR levels ≥4) in a cohort of patients taking warfarin. METHODS: A cohort of warfarin users aged 18 to 85 years from January 2005 to April 2013 was identified in The Health Improvement Network U.K. primary care database (N = 12,506). A random date was assigned to all patients within their eligible person-time (index date), and a nested case-control analysis was performed with individuals presenting a first episode of INR level ≥4 after the index date used as cases (N = 699) and patients with non-supratherapeutic INR values (≤3) as controls (N = 9,798). Using unconditional logistic regression models, odds ratios with 95% confidence intervals were calculated adjusted for potential confounders. Two sensitivity analyses were performed with alternative definitions of over-anticoagulation (INR levels ≥5 or > 3). RESULTS: Among the factors examined, the strongest predictors of over-anticoagulation were warfarin indication (in particular, valvular atrial fibrillation and valve replacement), renal failure (with the risk increasing steeply with decreasing estimated glomerular filtration rate), cancer, anaemia, respiratory infections treated with antibiotics, chronic obstructive pulmonary disease treated with ß2-agonists, polypharmacy (≥10 medications), low socio-economic status and residency in rural areas. Similar results were obtained when supratherapeutic levels were defined as INR ≥5 or, alternatively, as INR > 3. CONCLUSION: Predictors of supratherapeutic INR levels found in this study might help physicians identify patients where closer INR monitoring is warranted.

Intensive community pharmacy intervention had little impact on triptan consumption: a randomized controlled trial.

OBJECTIVE: To evaluate the impact of an intensive pharmaceutical care campaign targeting inappropriate use of triptans. DESIGN: Randomized controlled trial. SETTING: 22 community pharmacies in the County of Funen, Denmark. SUBJECTS: A total of 1123 triptan users at intervention pharmacies and 1340 at control pharmacies. INTERVENTION: Intervention pharmacy staff received information on migraine and other types of headache, detection of inappropriate triptan use and other drug-related problems, and techniques for establishing a dialogue with patients. Intervention consisted of a folder and a structured dialogue with the pharmacy staff. The folder included questions aimed at detecting overuse and inappropriate triptan use. MAIN OUTCOME MEASURES: Change in average triptan consumption in doses per month measured by means of a prescription database with information on all purchases of reimbursed drugs at the level of the individual patient. RESULTS: Overall, intervention had no statistically significant short-term impact on patients' consumption of triptans either among incident users (intervention/control ratio 1.02; 95% confidence interval 0.95 to 1.12), or among prevalent users (1.02; 0.97 to 1.08). No effects were observed after 6 and 9 months, apart from a possible borderline effect after 9 months among prevalent users with intermediate triptan consumption (0.93; 0.87 to 1.00). CONCLUSION: The pharmaceutical care campaign did not reduce the use of triptans.