Page 76 - ADD-ON ABLATION SURGERY IN PATIENTS WITH ATRIAL FIBRILLATION

Chapter 9
Apart from the above-mentioned limitations regarding the energy source employed, general limitations on QoL research in AF patients should be addressed as well, as QoL measurements might not appropriately reflect the disease specific burden. For a HrQoL or subjective assessment measure to be valid, it must accurately measure its target construct. Life events and other chronic diseases, besides in our case AF, also influence HrQoL: this clouding effect enhances while follow-up extends over time.As these additional individual influences are usually not known by researchers, it is unclear how respondents interpret questions. Respondents impute their overall subjective health considerations, not just from a perspective regarding their AF burden, in questionnaire scale responses. Furthermore, data from QoL questionnaires are often used for purposes different from which they were originally designed. Since validated disease specific questionnaires for AF are lacking, it is appealing to use a generic QoL questionnaire as a core module with a disease-specific module added to it, in order to assess proper QoL evaluation. In this way, measurements would be maximally valid and responsive to change in health status for AF patients. In our HrQoL study, we used two generic questionnaires: SF-36 and EuroQoL. Although these questionnaires have been widely used in arrhythmia studies and even in ablation surgery trials, they have not been designed to detect HrQoL changes in the specific AF patient population28, 31, 36, 37.The MFI-20 was considered as being a disease-specific questionnaire since it addresses different aspects of fatigue, which is one of the key symptoms of AF. Although the MFI-20 seemed to be more subtle in detecting changes in QoL through SR conversion, a validated AF-specific questionnaire will be indispensable in future QoL research.
A further step of our research was to assess cost-effectiveness of add-on surgery and to compare it to isolated cardiac surgery procedures.
The costs ofAF were collected during one year,at baseline and at two to six weeks, three to four months, six to seven months and 11-12 months postoperatively, by means of the cost diary method in which participants continuously recorded volumes of healthcare utilization38.
The diary contained questions regarding three categories of costs, which were evaluated from a societal perspective: direct healthcare costs (costs of visits to the general practitioner, prescribed medication, etc.), direct non-healthcare costs (counter medication and informal help) and indirect costs (work status and absence, voluntary work, informal care etc.). To calculate the incremental cost-effectiveness ratio (ICER), the difference in costs between two treatment
194