Considerations about the threshold value of microalbuminuria in patients with diabetes mellitus: lessons from an 8-year follow-up study of 599 patients.
OBJECTIVE
To examine the validity of the time honored threshold value for microalbuminuria of 30 mg/24 h, by analyzing an 8-year follow-up data of 599 patients with diabetes mellitus type 2, normal blood pressure and base-line albumin excretion rate (AER) </=30 mg/24 h.


METHODS
The patients were allocated to three groups according to the baseline values of AER. Group I: 0-10 mg/24 h; Group II: 10.1-20 mg/24 h; Group III: 20.1-30 mg/24 h.


RESULTS
Progression to microalbuminuria during follow-up occurred in 25.3, 47.3 and 85.3% of the patients in Group I, II and III, respectively. Compared to Group I, the risk to progress to microalbuminuria was 2. 34 (95% CI 1.32-4.43, P=0.029) in patients of Group II and 12.36 (95% CI 8.9-16.5, P=0.0001) in Group III. The average annual decline in glomerular filtration rate (GFR) was 1.19, 1.64 and 2.52 ml/min per year, respectively in the three groups. The correlation between baseline AER values and subsequent decline in GFR was exponential without a clear threshold value. Compared to Group I, the odds ratio for any cardiovascular end point (e.g. death, non-fatal myocardial infarction etc.) was 1.9 (95% CI 0.8-2.5, P=0.22) for patients of Group II and 9.8 (95% CI 6.7-12.3, P=0.001) for Group III.


CONCLUSIONS
The present study shows that patients with baseline AER values of 20.1-30 mg/24 h show an accelerated decline in GFR and significantly higher risk for cardiovascular events than patients with AER values below 20 mg/24 h. Though AER is obviously a continuous variable, the arbitrary threshold value for screening and for preventive strategies should probably be set at 20 rather than at 30 mg/24 h.
Rachmani
R
R
Department of Medicine, Meir Hospital Kfar-Sava, Sackler Faculty of Medicine, Tel-Aviv University, 44281, Kfar-Sava, Israel.
Levi
Z
Z
Lidar
M
M
Slavachevski
I
I
Half-Onn
E
E
Ravid
M
M
D000419:Albuminuria; D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000453:epidemiology; D003924:Diabetes Mellitus, Type 2 / Q000401:mortality / Q000503:physiopathology* / Q000652:urine*; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015996:Survival Rate; D013997:Time Factors