Table 1.

Characteristics of participants, overall and by 24-hour urine volume at baseline

Overall (n = 2148)24-hour Urine VolumePa
<1 L (n = 312)1 to 1.9 L (n = 1107)2 to 2.9 L (n = 564)≥3 L (n = 165)
Female gender1207 (56.2%)182 (58.3%)607 (54.8%)328 (58.2%)90 (54.5%)0.48
Age at entry (years), mean (SD)46.3 (15.0)39.2 (14.5)46.0 (15.3)50.2 (13.6)48.4 (13.9)<0.001
Age at last follow-up (years), mean (SD)51.5 (15.3)44.3 (14.7)51.2 (15.6)55.6 (13.9)53.9 (14.0)<0.001
Years followed, median (IQR)5.7 (3.9, 6.0)5.6 (3.8, 6.0)5.7 (3.8, 6.0)5.8 (4.1, 6.0)5.8 (4.3, 6.1)0.001
Number of eGFR assessments, median (IQR)6.0 (4, 7)6 (4, 7)6 (4, 7)6 (5, 7)7 (5, 7)0.001
24-hour urine volume (L), median (IQR)1.8 (1.2, 2.2)0.8 (0.65, 0.9)1.4 (1.2, 1.7)2.3 (2.2, 2.6)3.3 (3.1, 3.8)<0.001
eGFR ml/min per 1.73 m2, mean (SD)86.9 (15.2)90.3 (15.5)87.6 (15.6)83.8 (14.1)86.5 (13.9)<0.001
Serum creatinine (mg/dl), mean (SD)0.88 (0.15)0.88 (0.15)0.88 (0.15)0.89 (0.14)0.88 (0.14)0.61
Dipstick protein ≥1 g/L41 (1.9%)9 (2.9%)18 (1.6%)11 (2.0%)3 (1.8%)0.02
Obese (BMI ≥30 kg/m2)783 (36.5%)97 (31.1%)402 (36.3%)214 (37.9%)70 (42.4%)0.07
Family history
    hypertension955 (44.5%)128 (41.0%)492 (44.4%)255 (45.2%)80 (48.5%)0.44
    kidney failure52 (2.4%)10 (3.2%)21 (1.9%)13 (2.3%)8 (4.8%)0.10
    diabetes584 (27.2%)68 (21.8%)311 (28.1%)162 (28.7%)43 (26.1%)0.12
Smoker970 (45.2%)113 (36.2%)502 (45.3%)271 (48.0%)84 (50.9%)0.003
Medications for hypertension (including diuretics)601 (28.0%)50 (16.0%)306 (27.6%)189 (33.5%)56 (33.9%)<0.001
Diabetes270 (12.6%)31 (9.9%)132 (11.9%)83 (14.7%)24 (14.5%)0.15
Cardiovascular disease175 (8.1%)15 (4.8%)92 (8.3%)57 (10.1%)11 (6.7%)0.05
  • Values are numbers (percentages) unless stated otherwise (n = 2148). IQR, interquartile range; eGFR, estimated GFR; BMI, body mass index.

  • a Variables were compared using the chi-squared test, analysis of variance, or the Kruskal-Wallis test, as appropriate.