AJKD：单次测量基线蛋白尿 肾脏不良预后风险易低估

近日，《美国肾脏病杂志》(American Journal of  Kidney Diseases）发表了加拿大阿尔伯塔大学医院研究人员的研究结果，单次测量基线蛋白尿易低估肾脏不良预后风险。

研究者在加拿大阿尔伯塔省开展纵向研究，测试入组成年人的蛋白尿水平（试纸测量）、计算尿白蛋白/肌酐比值(Albumin creatinine ratio，ACR)。记录受试者的全因死亡率、终末期肾脏疾病发病。

测量：记录受试者门诊尿试纸测定的蛋白尿水平，分别记录蛋白尿的上限（到上一个整数级的中位值）、下限（到下一个整数级的中位值）、高值（测量最高值），低值（测量最低值），首次值（第一次测量值）。以同样方式记录尿白蛋白/肌酐比值。

结果：920985人参加研究，160548人（17％）接受多次尿试纸测量蛋白尿水平，22814人（22％）多次计算尿白蛋白/肌酐比值。与多次测量受试者相比，单次测量人群在不同蛋白尿水平的绝对死亡率、肾脏不良预后发生率更低，但是随着蛋白尿升高而相对增加的风险比值比更高。

结论：基线蛋白尿水平测定如果仅依靠首次测量而放弃随访测量，在任何蛋白尿水平都会导致对患者肾脏不良预后绝对和相对风险的低估。（生物谷Bioon.com）

doi:10.1053/j.ajkd.2011.09.006
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Multiple Versus Single and Other Estimates of Baseline Proteinuria Status as Predictors of Adverse Outcomes in the General Population

Aminu Bello, MD, PhD, Stephanie Thompson, MD, Anita Lloyd, MSc, Brenda Hemmelgarn, PhD, MD, Scott Klarenbach, MD, MSc1, Braden Manns, MD, MSc, Marcello Tonelli, MD

Background

The association of proteinuria and adverse clinical outcomes is well established. The optimal method of classifying proteinuria status for study participants in whom it is measured multiple times is unknown, especially when the frequency of measurement varies between participants.

Study Design

Population-based longitudinal study.

Setting & Participants

All adults with at least one outpatient serum creatinine measurement in the province of Alberta, Canada.

Factor

Proteinuria (dipstick, albumin-creatinine ratio [ACR]).

Outcomes

All-cause mortality, end-stage renal disease, or doubling of serum creatinine level.

Measures

All outpatient urine dipstick and ACR measurements in the 6-month period before and after the first (index) estimated glomerular filtration rate were used to establish baseline proteinuria. Dipstick measures were analyzed as ceiling (median value up to the next integer), floor (median value down to the next integer), high (single highest dipstick value), low (single lowest dipstick value), and first (first available dipstick value only). Measurements of ACR were evaluated similarly and a median (median of all ACR measurements) value was added.

Results

Of 920,985 participants, 17% (n = 160,548) had multiple dipstick urinalysis measurements and 22% (n = 22,814) had multiple ACR measurements. With single measurements, absolute rates of mortality and renal outcomes were lower in every proteinuria category compared with multiple measurements. In contrast, the relative increase in rate ratio was greater with increasing proteinuria in patients with single measurements compared with those with multiple measurements. In all classification systems evaluated, more severe proteinuria was associated with significantly higher rates of both outcomes (all P for trend <0.001).

Limitations

Lack of a gold standard for choosing between methods.

Conclusions

Rates of adverse outcomes related to multiple baseline proteinuria/albuminuria measurements were similar, independent of the measure of baseline proteinuria that was used to combine results. In contrast, discarding follow-up measurements and relying on only the first measurement led to lower estimates of absolute and relative risk for each proteinuria category.