Browsing School, Graduate by Title "Quality of life and physiological status as predictors of mortality in patients with implantable cardioverter defibrillators"
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Quality of life and physiological status as predictors of mortality in patients with implantable cardioverter defibrillatorsBackground. Sudden cardiac death (SCD) is one of the most common causes of death in developed countries throughout the world. The implantable cardioverter-defibrillator (ICD) has been established as an efficient treatment for prevention of SCD. Patients with ICDs commonly experience psychological distress and life change. It is important to assess the impact of the ICD treatment not only on improving survival but also on patients' life quality. Purpose. This study aimed to examine the predictors of quality of life and mortality, and to determine the relationship between quality of life and mortality in patients with ICDs. Methods. This study used the dataset from the Antiarrhythmic Versus Implanted Defibrillator (AVID) controlled clinical trial conducted by the National Institutes of Health (NIH), National Heart, Lung, and Blood Institute. The 507 patients randomly assigned to the ICD treatment in AVID study were recruited in the analysis. The subjects were mostly male (78.3%), with mean age of 64.85+/-10.81 years, mean ejection fraction (EF) of 32.2+/-13.45%, and 19.7% in NYHA (New York Heart Association) I, 28.4% in NYHA II, and 6.7% in NYHA III. The QOL was measured by the SF-36 at baseline, 3 months, 6 months, and 1 year follow-up and by the Quality of Life Index-Cardiac Version (QLI-CV) at baseline and 1 year follow-up. Depression was evaluated by the Mental Health Inventory-5 Items (MHI-5). Data were analyzed by descriptive statistics, multiple regression, logistic regression and Cox regression. Results. The mean total survival time for the ICD patients was 2.61+/-1.24 years. Approximately 25% of the ICD patients (n = 125) died during the period of AVID study. Among these 125 patients, 54 patients survived less than one year. Comparing the scores of QOL measurement at baseline with the scores at one year, PCS (physical component summary score) and MCS (mental component summary score) significantly improved, and QOL-CV increased but did not achieve significance. The ICD patients who received ACEI (angiotensin-converting enzyme inhibitor) therapy, who were younger, who had more stress perception at baseline, and who had better QOL (QLI-CV) had higher possibility of surviving more than one year after ICD implantation. Beyond the effect of bio-psycho-social factors, better QOL (QLI-CV) predicted more than one year survival. For the long-term mortality, the ICD patients who were older, who had more abnormal ECGs (electrocardiogram), who had a history of diabetes, and who perceived their physical health status as worse at last assessment (PCS time-dependent covariate) had a higher risk of dying. Adjusting for the bio-psycho-social factors, worse physical health status (PCS time-dependent covariate) still predicted mortality. Conclusion. Quality of life is an important factor predicting mortality in patients with ICDs. Large numbers of abnormal ECGs, having a history of diabetes, without receiving ACEI therapy, less stress perception at baseline, and older age predict mortality as well.