Challenges and Treatment for Stroke Prophylaxis in Patients with Atrial Fibrillation in Mexico: A Review

A Single-blind, Randomized, Single-dose, Two-sequence, Two-period, Crossover Study to Assess the Bioequivalence between Two Oral Tablet Formulations of Rivaroxaban 20 mg in Healthy Mexican Volunteers

The objective of this study was to demonstrate the bioequivalence of 2 oral tablet formulations of rivaroxaban 20 mg in healthy Mexican volunteers under fed conditions. This phase I, single‐blind, single‐dose, randomized, two‐sequence, two‐period crossover study included 32 volunteers. Subjects were randomly assigned to one of two sequences: test formulation (single 20 mg dose) in the first period followed by the reference formulation (single 20 mg dose) in the second, or vice versa. Blood samples were collected predose and at predefined timepoints across a 48‐hour period after drug intake. Rivaroxaban plasma concentrations were measured using a validated high‐performance liquid chromatography‐tandem mass spectrometry method. Pharmacokinetic parameters included maximum plasma concentration (C_max), area under the plasma concentration‐time curve from time zero to last measurable concentration and to infinity (AUC_0‐t, AUC_0‐∞), time to reach C_max, and half‐life. Safety was evaluated through adverse‐event monitoring using subject interviews and recording of vital signs. The 90% confidence intervals for the test/reference geometric mean ratios of C_max (100.4%–112.7%), AUC_0‐t (96.5%–111.6%), and AUC_0‐∞ (95.5%–109.5%) were within the bioequivalence acceptance range (80‐125%). Two adverse events (headaches) were recorded. Both formulations of rivaroxaban 20 mg tablets were bioequivalent and well tolerated in a healthy population of Mexican volunteers under fed conditions.

Prescription of oral anticoagulation in geriatric patients with atrial fibrillation

Objective

To determine the prevalence of prescription of oral anticoagulation in patients aged > 60 years with nonvalvular atrial fibrillation (NVAF).

Methods

Observational, cross-sectional, retrospective study based on a review of the clinical ­histories of patients aged >60 years diagnosed with NVAF from July 1 to September 30, 2019 and seen at the outpatient clinic (cardiology, internal medicine, geriatrics) of a secondary-level hospital in Queretaro, Mexico. Clinical profile and oral anticoagulant treatment were analyzed.

Results

The study population comprised 300 patients (mean age, 77.2±8.3 years; 53.3% women; 81% attended in cardiology). Of these, 91% had a high thromboembolic risk, 22.7% a high bleeding risk, and 1.7% contraindications for anticoagulation. Comorbidity was frequent. As for therapy, 82.7% were taking direct oral anticoagulants (DOAC), 11.0% vitamin K antagonists (VKA), and 6.3% no anticoagulant treatment. Anticoagulant therapy was inappropriate in 29.3% of patients, mainly because DOAC were prescribed without adjusting for age, weight, or serum creatinine and administered without indication according to thromboembolic risk. Only 39.4% of patients taking VKA were within the therapeutic range. Of all patients receiving DOAC, 48.0% were taking rivaroxaban, mainly at 20 mg/d (73.1%).

Conclusions

Thromboembolic risk is high in geriatric patients with NVAF. Anticoagulation is contraindicated in <2% of patients. Oral anticoagulants are prescribed inappropriately in three out of ten patients.

The cost of warfarin treatment for stroke prevention in patients with non-valvular atrial fibrillation in Mexico from a collective perspective

AIMS

To describe the collective costs of vitamin K antagonist (VKA) treatment for stroke prevention in non-valvular atrial fibrillation (NVAF). VKA drug costs are relatively low, but they necessitate frequent international normalized ratio (INR) monitoring. There are currently minimal data describing the economic impact of this in Mexico.

MATERIALS AND METHODS

Cardiologists provided data on their NVAF patients (n = 400) to quantify direct medical costs (INR testing, appointments, drug costs). A sub-set of patients (n = 301) completed a patient questionnaire providing data to calculate direct non-medical costs (travel and other expenses for attendance at VKA-associated appointments) and indirect costs (opportunity cost and reduced work productivity associated with VKA treatment).

RESULTS

Estimated annual direct medical costs totaled $753.6 per patient. Annual direct non-medical and indirect costs were USD$149.8 and $132.1, respectively.

LIMITATIONS

Recruited patients were those who consulted with a cardiologist during the study period and selected due to inclusion criteria. All had received uninterrupted treatment for 12-24 months. Consequently, the results are not fully generalizable to all VKA treated NVAF patients.

CONCLUSIONS

The true cost of VKA treatment cannot be appreciated by a consideration of drug costs alone. Ongoing monitoring appointments incur additional expenses for both patients and the healthcare system.