Center for Health Quality, Outcomes, and Economic Research, Edith Nourse Rogers Memorial Veterans Hospital, Bedford, MA 01730, USA.
Am J Kidney Dis. 2010 Oct;56(4):651-60. doi: 10.1053/j.ajkd.2010.05.011. Epub 2010 Jul 29.
Existing acute kidney injury (AKI) definitions are not well adapted for database studies, leading to a great variety of methods used in research. Variations in time before hospitalization used to assess baseline kidney function when identifying episodes of AKI may lead to different case samples and mortality risks in database studies, but the magnitude of these effects is not known.
A retrospective cohort study.
SETTINGS & PARTICIPANTS: 1,126,636 veterans hospitalized at least once within the US Department of Veterans Affairs health care system between 2000 and 2005.
AKI was defined by comparing (using ratio [≥1.5] or difference [increase of 0.3-0.5 mg/dL]) the highest serum creatinine level during hospitalization with the lowest level during 4 different baseline assessment periods (in-hospital only and 3, 6, or 12 months preadmission).
OUTCOMES & MEASUREMENTS: In-hospital mortality risk was estimated using multivariable logistic regression models.
Using the ratio definition, the cumulative incidence of AKI ranged from 12.5% (in-hospital only) to 18.3% (12 months preadmission). Newly added cases had milder AKI and lower mortality risk. The discriminative power increased slightly (C statistic increased from 0.846 to 0.855; P = 0.001) by extending the baseline period to at least 3 months. Both the ratio and difference definitions did not perform well in patients with chronic kidney disease stages 4 and 5.
Possibility of residual confounding and under-representation of women (4.5%).
Many additional AKI cases may be identified by extending the baseline assessment period; however, added cases may be less severe with lower mortality risk. The relative strengths of these biases and combined effects of reducing misclassification (identification of more AKI cases) and increasing risk dilution (identifying milder cases) may vary across populations. Consensus regarding how baseline kidney function should be determined in database studies should be reached.
现有的急性肾损伤（AKI）定义并不适合数据库研究，导致研究中使用了各种不同的方法。在识别 AKI 发作时，用于评估基线肾功能的住院前时间的差异可能导致数据库研究中的病例样本和死亡风险不同，但这些影响的程度尚不清楚。
回顾性队列研究。
2000 年至 2005 年期间至少在美国退伍军人事务部医疗保健系统住院一次的 1126636 名退伍军人。
通过比较（使用比值[≥1.5]或差值[增加 0.3-0.5mg/dL]）住院期间最高血清肌酐水平与 4 个不同基线评估期（仅住院期间以及入院前 3、6 或 12 个月）的最低水平，来定义 AKI。
使用多变量逻辑回归模型估计住院期间的死亡率风险。
使用比值定义，AKI 的累积发生率范围为 12.5%（仅住院期间）至 18.3%（入院前 12 个月）。新增加的病例 AKI 程度较轻，死亡风险较低。通过将基线期至少延长至 3 个月，区分能力略有提高（C 统计量从 0.846 增加到 0.855；P=0.001）。慢性肾脏病 4 期和 5 期患者的比值和差值定义均表现不佳。
可能存在残余混杂和女性代表性不足（4.5%）。
通过延长基线评估期，可能会发现更多的 AKI 病例；但是，添加的病例可能不那么严重，死亡风险较低。这些偏倚的相对强度以及减少错误分类（识别更多 AKI 病例）和增加风险稀释（识别更轻微的病例）的综合效应可能因人群而异。应就数据库研究中如何确定基线肾功能达成共识。
