SNAP AF-52: Dose Appropriateness and Adherence to Oral Anticoagulation in Adults ≥65 With Atrial Fibrillation in Primary Care (Ordu, Türkiye)

N/ANot Yet RecruitingNCT07242326

Kotyora Family Medicine Health Management and Education Association1,000 enrolled

Overview

SNAP AF-52 is an ambidirectional observational registry conducted in family health centers (primary care) across Ordu, Türkiye, enrolling adults ≥65 years with a pre-existing diagnosis of atrial fibrillation. The study assesses (a) label-concordant dosing of oral anticoagulants (DOACs/warfarin) using drug-specific criteria, and (b) medication adherence via Proportion of Days Covered (PDC) over the prior 12 months (good adherence defined as PDC ≥80%). Unsafe findings (e.g., suspected under-/overdosing, critical drug-drug interactions, very low renal function) trigger same-day referral to tertiary cardiology for evaluation and management. The retrospective window is Dec 1, 2024-Nov 30, 2025; the prospective single-visit inclusion window is Dec 1, 2025-May 31, 2026. No experimental treatment is administered; all care is routine.

Family physicians will screen their ≥65-year attendees with documented AF and record a minimum dataset during a single routine visit: demographics, body weight, most recent serum creatinine (date/value) to compute Cockcroft-Gault creatinine clearance (CrCl), current oral anticoagulant and regimen, common interacting drugs, and pharmacy dispensing dates with days' supply for the last 12 months. The system auto-classifies dose appropriateness per drug label criteria (including apixaban reduction rules; rivaroxaban/dabigatran/edoxaban CrCl thresholds and P-gp/CYP3A4 interactions) and computes PDC with carry-over of early refills; primary nonadherence is defined as no fill within 30 days of the first prescription. Retrospective capture of events includes ischemic stroke/TIA/systemic embolic event (SEE) and hemorrhagic stroke/ISTH major bleeding, plus on-treatment status at the event date. Participants with potentially unsafe dosing or clinically high-risk interaction (e.g., strong inducers; strong dual inhibitors) or CrCl \<15 mL/min are same-day referred to tertiary cardiology. Identifiable data will be stored securely per ethics approval and Turkish data protection (KVKK); only aggregated results will be reported.

Study Type

OBSERVATIONAL

Enrollment

1,000

Conditions

Medication Adherence

Eligibility

Sex: ALLMin age: 65 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Age ≥65 years. * Established atrial fibrillation (any type) documented in the medical record. * Presenting to a family health center (primary care) in Ordu province during the prospective window or having records within the retrospective window. * On an oral anticoagulant (DOAC) at any time in the 12-month window. Exclusion Criteria: * Mechanical prosthetic heart valve or moderate-to-severe rheumatic mitral stenosis * Participation in an interventional drug study affecting anticoagulation * Lack of minimal data elements required for dose classification (age, sex, body weight, serum creatinine with date, current OAC and regimen) * Investigator judgment that reliable data cannot be obtained from records

Outcomes

Primary Outcomes

Primary Outcome 1: Label-Concordant Dose Proportion

Proportion of patients on label-concordant dose vs underdose vs overdose, by anticoagulant. Criteria include: Apixaban: 5 mg BID (standard) or 2.5 mg BID if ≥2 of: age ≥80 years, weight ≤60 kg, serum creatinine ≥1.5 mg/dL. Rivaroxaban: 20 mg QD if CrCl ≥50 mL/min; 15 mg QD if CrCl 15-49; avoid/evaluate if CrCl \<15. Dabigatran: 150 mg BID (standard); 110 mg BID considered if age ≥80 or if CrCl 30-50 and P-gp inhibitor; avoid/evaluate if CrCl \<30. Edoxaban: 60 mg QD (standard); 30 mg QD if CrCl 15-50, weight ≤60 kg, or specific P-gp inhibitors (e.g., dronedarone, verapamil, erythromycin, ketoconazole, cyclosporine); consider reduced efficacy if CrCl \>95.

Time frame: At index visit (assessed using baseline variables and the most recent renal function).

Primary Outcome 2: Good Adherence (PDC ≥80%)

Proportion of Days Covered (PDC) = (covered days / 365), with early refill carry-over and single-day duplicate fills not double-counted. Good adherence: PDC ≥80% (class-level and drug-specific PDC reported).

Time frame: Prior 12 months relative to index date

Secondary Outcomes

Secondary Outcome 1: Primary Nonadherence

Yes if no pharmacy dispensing within 30 days of the first OAC prescription.

Time frame: From first prescription within the 12-month

Secondary Outcome 2: Ischemic Events

Proportion with ischemic stroke (ICD-10 I63.x), TIA (G45.x), or systemic arterial embolic event (I74.x); event-date on-treatment status derived from dispensing coverage.

Time frame: Prior 12 months.

Secondary Outcome 3: Hemorrhagic Events

Hemorrhagic stroke (I60-I62) and ISTH major bleeding (any of: fatal; critical site-including intracranial/intraspinal/intraocular/pericardial/intra-articular/intramuscular with compartment syndrome; Hb drop ≥2 g/dL; or ≥2 RBC units transfused). Location examples: GI (K92.2; K25-K28 with hemorrhage), GU (R31/N02), pulmonary (R04.2), intra-ocular (H43.1/H35.6).

Time frame: Prior 12 months

Secondary Outcome 4: Same-Day Tertiary Referral Rate

Proportion referred same-day to tertiary cardiology due to unsafe dose, high-risk interaction (e.g., strong inducer/strong dual inhibitor), or CrCl \<15 mL/min.

Time frame: At index visit