Modelling the cost-effectiveness of pharmacist-managed anticoagulation service for older adults with atrial fibrillation in Singapore

Abstract

Background Oral anticoagulation with warfarin is the cornerstone therapy in atrial fibrillation (AF) for stroke prevention. Multi-disciplinary anticoagulation management services have been shown to be cost-effective in the United States, Hong Kong and Thailand, but the findings are not readily generalizable to Singapore's healthcare system. Objective This study aimed to evaluate the cost-effectiveness of pharmacist-managed anticoagulation clinic (ACC) compared with usual care (UC) for the management of older adults with AF receiving oral anticoagulation with warfarin. Setting Pharmacist-managed ACC in an academic medical centre. Method A Markov model with 3-month cycle length and 30-year time horizon compared costs and quality-adjusted life-years (QALYs) of ACC and UC from the patient's and healthcare provider's perspectives. Four pathways based on time in therapeutic range (TTR) were: ACC TTR < 70 %, ACC TTR ≥ 70 %, UC TTR < 70 % and UC TTR ≥ 70 %. A hypothetical cohort of 70-year-old Singaporean AF patients receiving warfarin was utilised. Local data from national disease registries, patient surveys and hospital databases were used. When local data was not available, published studies on Asian populations were utilized when available. One-way sensitivity analyses and probabilistic sensitivity analyses were performed to account for uncertainties. Costs and QALYs were discounted annually by 3 %. Main outcome measure Costs and QALYs of ACC and UC. Results Pharmacist-managed ACC was found to dominate UC in all comparisons. It improved effectiveness by 0.19 and 0.13 QALYs at TTR < 70 % and TTR ≥ 70 % respectively compared with UC. From the patient's perspective, ACC reduced costs by SG$1222.67 (€1110.24) for TTR < 70 % and SG$1008.16 (€915.46) for TTR ≥ 70 %. Similar trends were observed from the healthcare provider's perspective, with ACC reducing costs by SG$1444.79 (€1311.94) for TTR < 70 % and SG$1269.17 (€1152.46) for TTR ≥ 70 % compared with UC. The results were robust to variations of the parameters over their plausible ranges in one-way sensitivity analyses. Probabilistic sensitivity analyses demonstrated that ACC was cost-effective more than 79 % of the time from both perspectives at a willingness-to-pay threshold of SG$69,050 (€62,701) per QALY. Conclusion Pharmacist-managed ACC is more effective and less costly compared with UC regardless of the quality of anticoagulation therapy. The findings support the current body of evidence demonstrating the cost-effectiveness of ACC.

Factors influencing warfarin control in Australia and Singapore

“…Subanalyses of the large comparative trials have demonstrated warfarin control of around 75% TTR in Australia and 65% TTR in Singapore. (12,16) Outside of these trials, the limited data on warfarin control in these countries have reported similar results with TTRs between 55%(17) and 81%(18) in Australia, and between 58% (19) and 65% (20) in Singapore. Wang et al (21) suggested the differential effects in warfarin control seen between Asians and non-Asians may be influenced by genetic polymorphisms, but also affected by demographic differences including body weight and renal function.…”

Evaluation of the clinical and safety outcomes of face‐to‐face vs a telephonic model of a pharmacist‐led outpatient anticoagulation service

“…Patients with AF were selected as they contribute to the bulk of the patient load at NUH. Exclusion criteria included: (1) Patients who switched between the two models of consultation within the study period, (2) Patients who were taking warfarin for other indications, especially for active clots such as heart thrombus or pulmonary embolism as these patients might cease warfarin therapy over the 6 months follow-up period, and…”

“…Numerous studies have shown that pharmacist-managed anticoagulation clinics (ACC) are more effective and less costly compared with usual care. [1][2][3][4][5][6][7][8] However, in terms of time requirements for patient visits to ACC, a study reported that a substantial amount of time, averaging 2.5 hours per visit and 40 hours per year, was spent on waiting time and travel. 9 At National University Hospital (NUH) in Singapore, ACC clinics have a monthly load of more than 1000 patients.…”

Pharmacoeconomic evaluation of providing pharmacist-managed anticoagulation service to patients on warfarin

“…Pored navedenih opservacionih studija, sprovedene su i farmakoekonomske evaluacije zasnovane na modelovanju dugoročnog uticaja menadžmenta antikoagulantne terapije varfarinom od strane farmaceuta na nivou hipotetičke kohorte [30,31]. Studija sprovedena u Singapuru od strane Chua i sar.…”

“…Studija sprovedena u Singapuru od strane Chua i sar. [30], imala je za cilj procenu troškovne isplativosti pružanja FZZ pacijentima na varfarinu sa indikacijom atrijalne fibrilacije, a iz perspektive pacijenta i finansirajuće institucije (3 rd party payer). Kreiran je Markovljev model sa tromesečnom dužinom ciklusa i tridesetogodišnjim vremenskim horizontom, pri čemu je vršeno poređenje troškova i humanističkih ishoda, izraženih kao godina života korigovana za kvalitet (Quality-adjusted life year-QALY).…”