Comorbidity, Costs and Outcomes in Dialysis Patients

随着透析患者的平均年龄增加到60岁，合并症（如糖尿病）的患病率增加，合并症的增加可能会对透析人群的发病率、死亡率和费用产生深远影响。量化合并症的有效工具可能有助于识别资源利用昂贵的高风险患者，有助于制定公共卫生策略，并确定针对该高风险人群的最佳透析治疗干预措施。为了在透析人群中有效，合并症工具应该简单、易于验证，包括影响透析患者结局的某些特定因素，如终末期肾病的持续时间，并包括客观、可量化的疾病严重程度指标。目前使用的指标，如查尔森合并症指数和共存疾病指数，都不符合所有这些标准。因此，本研究的具体目的是在大样本透析人群中开发和验证一种简单、特异于透析患者并能说明疾病严重程度的合并症指数。既往研究显示，合并症高的患者腹膜透析技术失败率较高。本研究还将检查腹膜透析技术失败后观察到的死亡率增加是否是由于这些患者的高合并症或技术失败本身导致死亡率升高。本研究将使用美国肾脏数据系统（USRDS）透析发病率和死亡率研究（DMMS）中的现有数据。合并症工具将从DMMS III研究中6300例流行患者的子集中开发。通过考克斯比例风险，确定每种共病的相对死亡风险，并根据相对风险给出评分。将在以下亚群中验证该评分系统：DMMS-IV研究中以医疗保险作为主要或唯一支付者的流行血液透析患者，DMMS-IV研究中以非医疗保险作为主要或唯一支付者的流行血液透析患者，DMMS wave II研究中1996年或1997年开始透析的偶发血液透析和腹膜透析患者，无论保险状态如何。关注的结局将是住院天数和医疗保险住院费用（通过ANOVA）和死亡（通过考克斯比例风险）。来自DMMS II的进一步数据将用于检查腹膜透析患者的死亡风险，这些患者在接受血液透析患者时技术失败。由于合并症可预测腹膜透析技术失败，上述分析将有助于在透析开始时根据合并症确定最佳透析方式。

As the mean age of incident dialysis patients has increased to 60 years and prevalence of comorbid conditions such as diabetes has increased, increasing comorbidity may profoundly impact on morbidity, mortality and costs in the dialysis population. A valid tool that quantifies comorbidity may help to identify high-risk patients with expensive resource utilization, help to flame public health strategies and define optimal dialysis therapeutic interventions targeted towards this high-risk group. To be valid in the dialysis population, the comorbidity tool should be simple, readily verifiable, include certain specific factors that influence outcomes in dialysis patients such as duration of end-stage renal disease and include objective, quantifiable measures of disease severity. None of the currently used indices such as the Charlson Comorbidity Index and the Index of Coexistent Diseases meet all of these criteria. Therefore, the specific aims of this study are to develop and validate in a large sample of dialysis population an index of comorbidity that is simple, specific for dialysis patients and accounts for disease severity. Prior studies showed patients with high comorbidity have higher peritoneal dialysis technique failure. This study will also examine whether the increased mortality observed after peritoneal dialysis technique failure is due to high comorbidity of these patients or the technique failure itself causes higher mortality. This study will use the existing data in the United States Renal Data System (USRDS) Dialysis Morbidity and Mortality Studies (DMMS). The comorbidity tool will be developed from a subset of the 6300 prevalent patients in the DMMS III study. By Cox proportional hazards, the relative risk for death, for each of the comorbid conditions will be determined and scores will be given based on the relative risk. This scoring system will be validated in the following sub-populations: prevalent hemodialysis patients with Medicare as the primary or sole payer in the DMMS-IV study, prevalent hemodialysis patients with non-Medicare as the primary or sole payer in the DMMS-IV study, incident hemo and peritoneal dialysis started on dialysis in 1996 or 1997 in the DMMS wave II study irrespective of the insurance status. The outcomes of interest will be hospital days and Medicare hospital costs (by ANOVA) and death (by Cox proportional hazards). Further data from DMMS II will be used to examine the risk of death of incident peritoneal dialysis patients who failed the technique with incident hemodialysis patients. As comorbidity predicts peritoneal dialysis technique failure, the above analysis will help in determining the optimal dialysis modality based on comorbidity at the initiation of dialysis.