Supplementary Material for: Blood pressure and Mortality in the 4D Study

Introduction: Systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) are risk factors for cardiovascular mortality (CVM). Pulse pressure (PP) is an easily available parameter of vascular stiffness, but its impact on CVM in chronic dialysis patients with diabetes is unclear.
Methods: Therefore, we have examined the predictive value of baseline, predialytic PP, SBP, DBP and MAP in the German Diabetes and Dialysis (4D) study, a prospective, randomized, double-blind trial enrolling 1255 patients with type 2 diabetes on hemodialysis in 178 German dialysis centers.
Results: Mean age was 66.3 years, mean blood pressure 146/76 mmHg, mean time suffering from diabetes 18.1 years and mean time on maintenance dialysis 8.3 months. Considered as continuous variables, PP, MAP, SBP and DBP could not provide a significant mortality prediction for either cardiovascular or all-cause mortality. After dividing the cohort into corresponding tertiles, we did also not detect any significant mortality prediction for PP, SBP, DBP or MAP, both for all-cause mortality and CVM after adjusting for age and sex. Nevertheless, when comparing the HR plots of the corresponding blood pressure parameters, a pronounced U-curve was seen for PP for both all-cause mortality and CVM, with the trough range being 70-80 mmHg.
Discussion: In patients with end-stage renal disease and long-lasting diabetes mellitus predialytic blood pressure parameters at study entry are not predictive for mortality, presumably because there is a very high rate of competing mortality risk factors, resulting in overall very high rates of all-cause and cardiovascular mortality, that may no longer be significantly modulated by blood pressure control.

引言：收缩压（SBP）、舒张压（DBP）及平均动脉压（MAP）均为心血管病死亡率（CVM）的风险因素。脉压（PP）是反映血管僵硬度的易于获取的参数，但其对患有糖尿病的慢性透析患者的CVM影响尚不明确。
方法：因此，我们检视了德国糖尿病与透析（4D）研究中基线、透析前脉压、SBP、DBP及MAP的预测价值。该研究是一项前瞻性、随机、双盲试验，纳入了178家德国透析中心的1255名正在血液透析的2型糖尿病患者的资料。
结果：平均年龄为66.3岁，平均血压为146/76毫米汞柱，平均患有糖尿病时间为18.1年，平均维持透析时间为8.3个月。将PP、MAP、SBP和DBP视为连续变量时，它们无法为心血管病或全因死亡率提供显著的预测。在将队列分为相应的三分位数后，调整年龄和性别后，也未发现PP、SBP、DBP或MAP对全因死亡率或CVM有显著的预测价值。尽管如此，在比较相应血压参数的HR曲线时，无论是全因死亡率还是CVM，PP均呈现出明显的U形曲线，其谷值范围为70-80毫米汞柱。
讨论：对于终末期肾病和长期糖尿病 mellitus患者而言，研究入组时的透析前血压参数对于死亡率的预测并无显著意义，这可能是由于存在极高的竞争性死亡率风险因素，导致整体全因和心血管病死亡率极高，血压控制可能已无法显著调节这些死亡率。