Quality of Oral Anticoagulation Control with Warfarin in Patients Followed at the Hematology Service of a Public Referral Hospital in Fortaleza, Ceará, Brazil: A Retrospective, Single-Center, Exploratory Study
Warfarin, a vitamin K antagonist, remains widely prescribed within resource-limited public health systems, but its narrow therapeutic index requires close monitoring through the International Normalized Ratio (INR) and the Time in Therapeutic Range (TTR). Real-world data on warfarin control within the Brazilian Unified Health System are scarce. We conducted a retrospective, single-center, exploratory observational study, reported following STROBE, to describe the quality of anticoagulation control in patients on chronic warfarin therapy at a public referral hematology service in Fortaleza, Brazil. Between August and September 2023, the longitudinal records of 34 adult patients (a convenience sample; about 12% of clinic warfarin users) were reviewed, comprising 879 PT/INR determinations analyzed against a target range of 2.0–3.0; TTR was estimated as the proportion of determinations within range. No sample-size calculation was performed, and analyses were descriptive. Approximately half of the determinations (456/879; 51.9%) were in range, and approximately one-third of patients (12/34; 35.3%) achieved a TTR above 60%, indicating predominantly suboptimal control. No thromboembolic events occurred during warfarin therapy; 28 patients (82.4%) self-reported adherence difficulties. These findings do not establish effectiveness but highlight the need to strengthen monitoring, adherence support, and multidisciplinary anticoagulation care. Results are hypothesis-generating.
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