据2月3日刊JAMA上的一则研究披露，具有高尿蛋白（尿液中的蛋白）加上另外一种肾功能降低的指标的患者与全因死亡率、心肌梗塞或进行性肾功能衰竭的风险增加有关。
有多达2600万美国人患有慢性肾脏疾病（CKD）。 目前的决定CKD阶段的系统主要是基于估计的肾小球滤过率（eGFR；它所测定的是肾脏过滤和清除废物的能力），而较低的eGFR与不良后果风险增加有关。 文章的作者写道：“…这些方针受到了人们的批评，因为它们并没有将蛋白尿的存在及其严重程度的资讯结合在内，而蛋白尿是CKD的一个与不良后果有关的重要标志。”
University of Calgary, Alberta, Canada的Brenda R. Hemmelgarn, M.D., Ph.D.及其同僚对eGFR降低、蛋白尿以及不良临床后果（其中包括全因死亡率、心肌梗塞以及进行性肾功能衰竭）之间的关系进行了调查。 研究人员分析了在某一省（阿尔伯塔）范围内的实验室登记数据（其中包括从2002-2007年期间的eGFR和蛋白尿测定）。 共有92万985名成人在研究开始的时候有过至少一次门诊做的血清肌酐检测，他们当时不需要做肾脏替代治疗（即：透析）。
研究人员发现，在各个水平的eGFR内，患者的风险都有相当大的可变性，那些尿蛋白含量较高者，其校正后的所有4种不良后果（即全因死亡率、心肌梗塞、终末期肾脏疾病以及血清肌酐浓度增加一倍[相当于肾功能下降50%]）的发生率都有所增加。 那些有严重蛋白尿但没有明显异常的eGFR患者看来比那些有轻度eGFR降低但无蛋白尿者的临床预后要更差。 在死亡、肾脏替代治疗的开始以及血清肌酐浓度加倍者中可观察到eGFR与蛋白尿之间存在着明显的相互作用。
文章的作者写道：“这些发现十分重要，因为目前用来为CKD进行分类和分级的治疗方针是基于eGFR的基础之上，而没有明确地考虑同时存在的蛋白尿的严重性。另外，电脑化报告的eGFR（通常不会考虑蛋白尿）已经越来越多地用来协助医师发现具有高风险不良预后的患者，或是那些可能需要接受专科医生治疗的患者。尽管我们的发现并没有直接说明哪些病人可得益于转诊到肾脏科医师，但它们确实提示，单以eGFR来作为风险分级对临床相关风险梯度来说是相对不敏感的。这些发现提示，将来在对CKD分类系统进行修正的时候应该包括蛋白尿的资料。”
推荐原始出处：
JAMA. 2010;303(5):423-429.
Relation Between Kidney Function, Proteinuria, and Adverse Outcomes
Brenda R. Hemmelgarn, MD, PhD; Braden J. Manns, MD, MSc; Anita Lloyd, MSc; Matthew T. James, MD; Scott Klarenbach, MD, MSc; Robert R. Quinn, MD, PhD; Natasha Wiebe, MMath, PStat; Marcello Tonelli, MD, SM; for the Alberta Kidney Disease Network
Context The current staging system for chronic kidney disease is based primarily on estimated glomerular filtration rate (eGFR) with lower eGFR associated with higher risk of adverse outcomes. Although proteinuria is also associated with adverse outcomes, it is not used to refine risk estimates of adverse events in this current system.
Objective To determine the association between reduced GFR, proteinuria, and adverse clinical outcomes.
Design, Setting, and Participants Community-based cohort study with participants identified from a province-wide laboratory registry that includes eGFR and proteinuria measurements from Alberta, Canada, between 2002 and 2007. There were 920 985 adults who had at least 1 outpatient serum creatinine measurement and who did not require renal replacement treatment at baseline. Proteinuria was assessed by urine dipstick or albumin-creatinine ratio (ACR).
Main Outcome Measures All-cause mortality, myocardial infarction, and progression to kidney failure.
Results The majority of individuals (89.1%) had an eGFR of 60 mL/min/1.73 m2 or greater. Over median follow-up of 35 months (range, 0-59 months), 27 959 participants (3.0%) died. The fully adjusted rate of all-cause mortality was higher in study participants with lower eGFRs or heavier proteinuria. Adjusted mortality rates were more than 2-fold higher among individuals with heavy proteinuria measured by urine dipstick and eGFR of 60 mL/min/1.73 m2 or greater, as compared with those with eGFR of 45 to 59.9 mL/min/1.73 m2 and normal protein excretion (rate, 7.2 [95% CI, 6.6-7.8] vs 2.9 [95% CI, 2.7-3.0] per 1000 person-years, respectively; rate ratio, 2.5 [95% CI, 2.3-2.7]). Similar results were observed when proteinuria was measured by ACR (15.9 [95% CI, 14.0-18.1] and 7.0 [95% CI, 6.4-7.6] per 1000 person-years for heavy and absent proteinuria, respectively; rate ratio, 2.3 [95% CI, 2.0-2.6]) and for the outcomes of hospitalization with acute myocardial infarction, end-stage renal disease, and doubling of serum creatinine level.
Conclusion The risks of mortality, myocardial infarction, and progression to kidney failure associated with a given level of eGFR are independently increased in patients with higher levels of proteinuria.
