ABC | Volume 113, Nº2, August 2019

Original Article Saad et al. Healthcare utilization and costs after ablation for AF Arq Bras Cardiol. 2019; 113(2):252-257 The aim of this study was to compare medical costs and ambulatory and hospital service use before and after catheter ablation in a cohort of Brazilian AF patients treated in the private healthcare system. Methods Study design and dataset This was a retrospective cohort study. The dataset used for the analyses was a patients’ reimbursement information from Orizon which contains a date-stamped log of all billed items by the cost-accounting department, including medications (only in-hospital use); laboratory, diagnostic, and therapeutic services; and primary and secondary diagnoses for each patient’s hospitalization. Both ambulatory and inpatient resource utilization are available in the dataset. About 12 million patients – which accounts from approximately 25% of patients in the Brazilian private healthcare system – are included in the Orizon patients’ billings databases. No informed consent was required because all data were from the patients' reimbursement information and their personal information was anonymous. All adult patients (over 18 years old) who had a hospital admission between January 2014 and December 2015 and underwent catheter ablation with an ICD-10 code of AF (I48) were potentially eligible for the current analysis. The following eligibility criteria must have been met for patient inclusion in the current analysis: • Elective radiofrequency ablation procedure, with a previous three-dimensional electrophysiologic mapping; • Available age, gender and ICD code information; • No registry of previous ablation procedures in the dataset; • Use of point by point ablation (standard irrigated, irrigated with contact force sensors and non-irrigated); • Minimum of 3 months of follow-up before and after the ablation procedure. Outcomes were evaluated both in the perioperative admission as well as in any readmission that occurred up to 2 years after the ablation procedure. Study variables The following variables were evaluated for each patient: age, gender, comorbidities (such as ischemic heart disease [IHD], chronic heart failure [CHF] and conduction disorders, among others), perioperative complications, short- and long- term AF recurrence-free rate, cardiovascular events, healthcare resources utilization (including ambulatory and emergency care) and costs. Details regarding variable definitions of these variables are described in the next paragraphs. Comorbidities were defined according to ICD-10 codes registered in the ambulatory and emergency visits from the patients in the database. AF recurrence was defined when a new ablation or a cardioversion procedure was performed or upon resumption of antiarrhythmic drug use in the follow-up period, after the three-month blanking period. The cardiovascular events evaluated (both in the pre- and post-procedural follow-up) were: acute coronary syndromes (ACS), stroke and arrhythmias. ACS was defined whenever a patient had requests for electrocardiogram plus either troponin or MB fraction of creatine kinase (CK-MB), as well as one of the following, billed items: any thrombolytic, angioplasty procedure, or a combination of medications highly suggestive of ACS (such as any form of heparin, antiplatelet drugs, nitrates, and statins). Ischemic stroke was defined when a patient had a request of either a computerized tomography or nuclear magnetic resonance of the brain, a prescription of antiplatelet agent or low-molecular-weight heparin, and billing of exams such as an echocardiogram, carotid doppler ultrasound, and an intensive care unit (ICU) admission. Hemorrhagic stroke was defined when a patient had a brain imaging exam (magnetic resonance or computerized tomography) and a compatible ICD-10, and admission to ICU. Arrhythmic events were defined when there were billed items related either to: electric cardioversion, internal cardioverter-defibrillator implantation, ablation procedure, surgical correction of arrhythmia, or prescription of in-hospital antiarrhythmic drugs suggestive of an acute arrhythmic event in patients where and electrocardiogram was also requested. The use of resources and their related costs were computed by summing all billed items (both ambulatory and emergency/ in-hospital care). Only cardiovascular related resources and costs were computed. To calculate mean monthly costs, we divided total costs by the number of follow-up months. Costs were further divided into ambulatory care, emergency related and elective admissions. Statistical analysis Continuous variables are presented as mean and standard deviation (SD) when they followed a normal distribution, and as median and interquartile range (IQR) when the distribution was non-normal. However, considering that cost (expressed as Brazilian Reais [BRL]) is usually a non-normal variable, but it is interesting to know the mean value since the total costs of any given sample of patients is equal to its mean times the total number of individuals, we present cost data in both ways. Categorical variables are presented as absolute values and proportions. Comparison between variables employed the Wilcoxon test for non-normally distributed variables and the paired student T-test for the ones with normal distribution. Fisher’s exact test was used to compare categorical variables between groups. The AF recurrence-free rate was evaluated with the Kaplan Meier methods. In the evaluation of possible predictors of better event-free survival, we used the log-rank test. When the same predictors were analyzed regarding their impact on the before-and-after cost difference, the Mann‑Whitney test was employed. All analyses were performed using SPSS version 20.0. A p-value of less than 0.05 was considered statistically significant. Results Among 179 potentially eligible patients, 83 fulfilled the eligibility criteria and were included in the analysis (Figure 1). 253