Detection of microalbuminuria. Receiver operating characteristic curve analysis favors albumin-to-creatinine ratio over albumin concentration.
OBJECTIVE
To compare albumin-to-creatinine ratio (ACR) and albumin concentration (ALB) for detection of microalbuminuria using precise data on CIs for sensitivity and specificity and to determine sex- and age-specific discriminator values for ACR.


METHODS
All consecutive patients investigated for the presence of microalbuminuria with timed overnight urine collection were included in the study. Results from 1.171 men and 1,223 women were eligible for evaluation. Albumin excretion rate (the reference procedure), ALB, and ACR were compared by receiver operating characteristic (ROC) curve analysis. Age- and sex-specific discriminator values were established. Sensitivity and specificity were determined, and their CIs were compared with those calculated from data presented in the literature.


RESULTS
Sensitivity and specificity were 89% (range, 85-92) and 90% (88-92), respectively, for women, and 90% (87-93) and 89% (86-91), respectively, for men, at a discriminator value of 15 mg/l for the ALB. This discriminator value did not show any relationship to sex or age. For the ACR, which depends on sex, the sensitivity and specificity were 94% (92-96) and 92% (91-94), respectively, at 2.5 g/mol for women and 94% (92-97) and 93% (91-95), respectively, at 1.8 g/mol for men. The discriminator value for the ACR appears to depend on age in both men and women.


CONCLUSIONS
ROC curve analysis clearly shows that the ACR performs better than the ALB in screening for microalbuminuria. However, in contrast to the ALB, the ACR needs sex- and age-specific discriminator values.
Bakker
A J
AJ
Department of Clinical Chemistry, Stichting Klinisch Chemisch Laboratorium, Leeuwarden, The Netherlands.
D000328:Adult; D000367:Age Factors; D000368:Aged; D000419:Albuminuria / Q000175:diagnosis*; D003404:Creatinine / Q000097:blood*; D003920:Diabetes Mellitus / Q000652:urine*; D003928:Diabetic Nephropathies / Q000175:diagnosis* / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012727:Sex Characteristics
D003404:Creatinine