The cost-effectiveness of implantable loop recorder detection of atrial fibrillation to prevent stroke in persons at high risk: An economic evaluation alongside a multicentre randomised controlled trial in Denmark (The LOOP Study)

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia although often asymptomatic and undiagnosed. AF is associated with an increased stroke risk that can be mitigated with anticoagulation. Heart rhythm monitoring with implantable loop recorders (ILR) is efficacious in the detection of asymptomatic AF which allows for preventive measures. The study aimed to examine whether screening with ILR and anticoagulation upon AF detection was cost-effective to prevent stroke. The study was designed as a cost-utility analysis alongside a randomised clinical trial. Its perspective was that of the health care and social care sector in Denmark. The time horizon was three years. Participants aged 70-90 years old with additional risk factors for AF and stroke were randomised to receive an ILR with anticoagulation upon detection of AF or to a control group. Quality-of-life (QoL) data were collected with the EQ-5D-5L instrument at baseline, 12, 24 and 36 months of follow-up. Danish tariffs were used to convert to health status measures to a QoL score to estimate quality-adjusted life-years (QALYs). Data on the participants' use of health care, social services and prescription drugs were found in Danish administrative registers. No participants had missing resource use data. Cost of the intervention with ILR was collected during the trial. Multiple imputation was performed to account for missing QoL data. Official tariffs, prices and agreements for health care, social services and medicines were used to estimate costs. All costs were calculated in 2022 prices. The costs and QALYs were discounted using an annual discount rate of 3.5%. Adjusting for 12 months of pre-baseline costs, the mean total discounted cost over the three years of follow up was 21,604 (95% CI 9,553 to 33,655) Danish kroner (DKK) higher in the ILR group than in the control group (1 DKK = 0.13 €). Adjusting for QoL at baseline, participants in the ILR group achieved an average of 2.2944 QALYs compared to 2.2807 QALYs in the control group. This is a difference of 0.0137 QALYs (95% CI -0.0091 to 0.0364). The probability of the ILR screening being cost-effective was less than 26% for defined threshold values for willingness to pay up to one million DKK per QALY gained. Screening for AF in 70-90-years-olds with an implantable loop recorder was not cost-effective within a time horizon of three years.