Page 36 - ADD-ON ABLATION SURGERY IN PATIENTS WITH ATRIAL FIBRILLATION

Chapter 2
concomitant medications. After discharge patients were seen in our outpatient clinics at 3, 6 and 12 months after surgery. Rhythm was evaluated by an EKG and additionally at 12-month follow-up a 24-hour Holter registration was performed.
Health-related quality of life questionnaires
For a comprehensive HrQoL assessment both generic and disease specific measurements were covered. One of two generic questionnaires that was used, the EuroQoL, consists of two components: description of the respondent’s own health by means of the EuroQoL thermometer (VAS, a visual analogue scale) and the EuroQoL classification (EQ-5D, mobility, self care, usual activities, pain/ discomfort, and anxiety/depression)6.The EuroQoL has been successfully used in HrQoL and cost-effectiveness research in heart patients11-12.The second generic questionnaire used in this study is the RAND 36-item Health Survey 1.0 (SF-36) comprising 8 multi-item scales13. Both generic questionnaires are standardized, validated and frequently used in arrhythmia studies8,10,4. The disease-specific questionnaire used, was the Multidimensional Fatigue Inventory (MFI-20)9. All questionnaires were self-administered before add-on surgery (baseline) at the hospital and were then sent by post during the follow-up period of 1-year and answered at home, at 3, 6 and 12 months after surgery.
Statistical analysis
Power analysis and patient characteristics
Sample size calculation was based on the expected rhythm outcome at 12-month follow-up. It was assumed that approximately 25% of patients in the control group would show spontaneous conversion to SR after 1-year follow-up. Power calculation was based on a minimal SR improvement of 25% one year after surgery. With a power of 80% and an alpha of 5% (2 sided), it was calculated that a minimum of 65 patients was needed per group. Correcting for loss of patients during follow-up, a total study population of 150 patients was targeted for the main study.All continuous variables are presented as means and standard deviations. Group comparison between continuous variables was performed, using the Student’s t-test in case of normal distribution; otherwise the Mann- Whitney-U test was applied. For all categorical data, the chi-square log-likelihood test was used.
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