Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology, Hypertension and Kidney Transplantation, Department of Medicine, School of Medicine, University of California Irvine, Orange, California, USA.
Fielding School of Public Health at UCLA, Los Angeles, California, USA.
Am J Nephrol. 2021;52(4):304-317. doi: 10.1159/000513855. Epub 2021 Apr 23.
Serum bicarbonate or total carbon dioxide (CO2) concentrations decline as chronic kidney disease (CKD) progresses and rise after dialysis initiation. While metabolic acidosis accelerates the progression of CKD and is associated with higher mortality among patients with end stage renal disease (ESRD), there are scarce data on the association of CO2 concentrations before ESRD transition with post-ESRD mortality.
A historical cohort from the Transition of Care in CKD (TC-CKD) study includes 85,505 veterans who transitioned to ESRD from October 1, 2007, through March 31, 2014. After 1,958 patients without follow-up data, 3 patients with missing date of birth, and 50,889 patients without CO2 6 months prior to ESRD transition were excluded, the study population includes 32,655 patients. Associations between CO2 concentrations averaged over the last 6 months and its rate of decline during the 12 months prior to ESRD transition and post-ESRD all-cause, cardiovascular (CV), and non-CV mortality were examined by using hierarchical adjustment with Cox regression models.
The cohort was on average 68 ± 11 years old and included 29% Black veterans. Baseline concentrations of CO2 were 23 ± 4 mEq/L, and median (interquartile range) change in CO2 were -1.8 [-3.4, -0.2] mEq/L/year. High (≥28 mEq/L) and low (<18 mEq/L) CO2 concentrations showed higher adjusted mortality risk while there was no clear trend in the middle range. Consistent associations were observed irrespective of sodium bicarbonate use. There was also a U-shaped association between the change in CO2 and all-cause, CV, and non-CV mortality with the lowest risk approximately at -2.0 and 0.0 mEq/L/year among sodium bicarbonate nonusers and users, respectively, and the highest mortality was among patients with decline in CO2 >4 mEq/L/year.
Both high and low pre-ESRD CO2 levels (≥28 and <18 mEq/L) during 6 months prior to dialysis transition and rate of CO2 decline >4 mEq/L/year during 1 year before dialysis initiation were associated with greater post-ESRD all-cause, CV, and non-CV mortality. Further studies are needed to determine the optimal management of CO2 in patients with advanced CKD stages transitioning to ESRD.
随着慢性肾脏病（CKD）的进展，血清碳酸氢盐或总二氧化碳（CO2）浓度下降，透析开始后上升。虽然代谢性酸中毒会加速 CKD 的进展，并与终末期肾病（ESRD）患者的死亡率升高有关，但关于 ESRD 过渡期前 CO2 浓度与 ESRD 后死亡率之间的关联的数据很少。
来自过渡时期肾脏病研究（TC-CKD）的历史队列包括 85505 名退伍军人，他们从 2007 年 10 月 1 日至 2014 年 3 月 31 日过渡到 ESRD。排除了 1958 名无随访数据的患者、3 名出生日期缺失的患者和 50889 名在 ESRD 过渡期前 6 个月没有 CO2 的患者后，研究人群包括 32655 名患者。使用 Cox 回归模型的层次调整，研究了最后 6 个月 CO2 浓度及其在 ESRD 过渡期前 12 个月内下降率与 ESRD 后全因、心血管（CV）和非 CV 死亡率之间的关系。
队列的平均年龄为 68 ± 11 岁，其中 29%为黑人退伍军人。CO2 的基线浓度为 23 ± 4 mEq/L，CO2 的中位数（四分位距）变化为-1.8[-3.4，-0.2]mEq/L/年。高（≥28 mEq/L）和低（<18 mEq/L）CO2 浓度显示出更高的调整后死亡率风险，而在中间范围内没有明显的趋势。在不考虑使用碳酸氢钠的情况下，观察到一致的相关性。在 CO2 变化与全因、CV 和非 CV 死亡率之间也存在 U 形关联，在不使用碳酸氢钠的患者中，大约在-2.0 和 0.0 mEq/L/年之间风险最低，而在 CO2 下降>4 mEq/L/年的患者中死亡率最高。
在透析转换前 6 个月内 CO2 水平较高（≥28 和<18 mEq/L）和在透析转换前 1 年内 CO2 下降率>4 mEq/L/年与 ESRD 后全因、CV 和非 CV 死亡率增加相关。需要进一步研究以确定在向 ESRD 过渡的晚期 CKD 患者中 CO2 的最佳管理方法。
