Cost effectiveness of ibutilide with prophylactic magnesium in the treatment of atrial fibrillation.

Background: In the Treatment with Ibutilide and Magnesium Evaluation (TIME) study, a retrospective multicentre cohort trial, prophylactic magnesium was found to improve the antiarrhythmic efficacy of ibutilide as demonstrated by an increase in the rate of successful chemical conversion and reduction in the need for direct current cardioversion (DCC).

Objective: The primary objective of this piggyback cost-effectiveness analysis of the TIME study was to compare the cost per successful conversion of atrial fibrillation (AF) for ibutilide in the presence and absence of magnesium prophylaxis. A secondary objective was to determine whether specific factors predict costs in the conversion of AF.

Method: The study was conducted from the US hospital-payer perspective. Direct medical costs (USD, 2002 values) including drugs, intravenous admixture and administration, DCC, electrocardiographs and physicians' fees were obtained directly from the provider. Nonparametric bootstrapping was conducted to calculate confidence intervals for the incremental cost-effectiveness ratios. One-way sensitivity analysis was conducted varying efficacy, and drug, hospital and physician costs. Multivariate analysis was conducted to determine whether specific baseline factors were predictors of total cost.

Results: Total costs per patient were lower in the ibutilide plus magnesium group compared with ibutilide alone (USD1075 vs USD1201); however, the difference was not statistically significant (p = 0.116). Patients receiving ibutilide plus magnesium had lower DCC costs compared with those receiving ibutilide alone (USD261 vs USD399; p = 0.036), but higher magnesium-associated costs (USD0.50 vs USD0; p < 0.001). Bootstrapping revealed that the ibutilide plus magnesium strategy would result in lower costs and greater efficacy 93.4% of the time. These results remained robust to changes in both cost and efficacy. No baseline factors were found to be independent predictors of total costs.

Conclusion: Our data suggest that adding prophylactic magnesium to ibutilide may be cost effective, from a US hospital-payer perspective, for the acute conversion of patients in AF or flutter compared with ibutilide alone.