Comparison of Urinary Albumin-Creatinine Ratio and Albumin Excretion Rate in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study

[摘要] Background and objectives: The objective of this study was to compare random urine albumin-creatinine ratio (ACR) with timed urine albumin excretion rate (AER) in patients with type 1 diabetes.Design, setting, participants, & measurements: A total of 1186 participants in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study provided spot urine specimens concurrent with 4-hour timed urine collections. ACR and AER were compared using Bland-Altman plots, cross-classification of albuminuria status and its change over time, and within-person variability.Results: Despite moderate correlation (r = 0.62), ACR levels (mg/g) were lower than AER levels (mg/24 hr). This difference was greatest for men. Gender-specific estimated AER (eAER) values were empirically derived from ACR. Comparing the eAER with measured AER, agreement of prevalent microalbuminuria and macroalbuminuria classification was fair to moderate, and classification of change in albuminuria status over time was different. Intraclass correlations were 0.697 for ACR and 0.803 for AER. Effects of DCCT intensive versus conventional diabetes therapy on urine albumin excretion or classification of albuminuria were similar using the eAER versus measured AER, as were the effects of the previous glycosylated hemoglobin.Conclusions: Systematic differences exist between urine ACR and AER, related to gender and other determinants of muscle mass. Use of ACR (or eAER) versus AER yields differences in classification of prevalent albuminuria states and changes in albuminuria states over time. These findings support the use of consistent ascertainment methods over time and further efforts to standardize and optimally interpret measurement of urine albumin excretion.The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Research Group has measured albumin excretion rate (AER) and creatinine clearance using a 4-hour timed urine collection and extrapolating results to a 24-hour excretion rate since its inception in 1983 (1). After 8 years in the EDIC follow-up study and after a mean study period of 14.5 years since DCCT baseline, we demonstrated an 87% reduction (95% confidence interval [CI] 65–95%; P < 0.001) in the risk for macroalbuminuria (AER >300 mg/24 h) in the intensive treatment group versus the conventional treatment group.In 2004, 21 years after the randomization of the first patient, DCCT/EDIC decided to evaluate use of the ratio of concentrations of albumin and creatinine (ACR) measured in untimed “spot” specimens. Measurement of urine ACR represents a less complex and time-consuming alternative to the 4-hour timed collection, which may also be less susceptible to imprecision due to incomplete or inaccurate collection (2–8). Herein, we describe the relationship between the ACR and AER as measures of albumin excretion and derive functions to estimate AER from ACR. We then evaluate the relative sensitivity and specificity of the estimated AER (eAER) relative to the timed collection for determination of microalbuminuria and macroalbuminuria and the degree of variation over time. We also assess the effects of initial DCCT treatment group (intensive versus conventional) and glycosylated hemoglobin (HbA1c) on the eAER compared with those of the timed AER to assess the potential sensitivity of the untimed “spot” collection to detect treatment or covariate effects.

[学科分类] 泌尿医学

[关键词] Bone marrow necrosis;Sickle cell disease;Hyperhemolysis syndrome