Table 1.

Baseline characteristics of study participants

CharacteristicsAll (n=525)UCr<1085 mg/24 h (n=262)UCr≥1085 mg/24 h (n=263)P Value
Men (%)304 (57.9)94 (35.9)210 (79.8)<0.001
Age, yr (mean± SD)56.9±15.761.2±15.152.7±15.1<0.001
Urine volume/d (ml)2090±6301910±5702270±630<0.001
Diabetes (%)96 (18.3)57 (21.8)39 (14.8)0.04
Charlson Comorbidity Index3.9±1.584.3±1.63.5±1.4<0.001
Primary renal disease, N (%)
 GN64 (12.2)26 (9.9)38 (14.4)0.11
 Diabetic nephropathy40 (7.6)21 (8)19 (7.2)0.73
 Tubulointerstitial diseasesa136 (25.9)68 (26)68 (25.9)0.98
 Multisystem diseasesb42 (8.0)22 (8.4)20 (7.6)0.74
 Hypertension50 (9.5)25 (9.5)25 (9.5)0.99
 Not known or other193 (36.8)100 (38.2)93 (35.4)0.51
SBP (mmHg)137.8±21.9139.6±24.5135.9±18.70.06
DBP (mmHg)79.5±11.178.6±12.080.5±10.10.07
CRP (mg/dl)0.7±1.50.8±1.50.6±1.50.45
Albumin (g/dl)4.2±0.54.1±0.54.2±0.40.004
Hemoglobin (g/dl)12.9±1.912.3±1.813.5±1.9<0.001
BMI (kg/m2)26.7±4.626.2±4.327.2±4.80.02
Bicarbonate (mEq/L)24.4±3.624.1±3.824.7±3.30.11
Protein intake (g/24 h)66.0±22.154.4±16.166.0±22.1<0.001
Proteinuria (g/24 h)1.2±1.21.1±1.21.3±1.30.14
Years of follow-up, median6.185.96.9<0.001
CKD stage 3a, N (%)86 (16.4)25 (9.5)61 (23.2)<0.001
CKD stage 3b, N (%)167 (31.8)75 (28.6)92 (35)0.12
CKD stage 4, N (%)192 (36.6)99 (37.8)93 (35.4)0.33
CKD stage 5, N (%)80 (15.2)63 (24)17 (6.5)<0.001
  • UCr, 24-hour urinary creatinine; SBP, systolic BP; DBP, diastolic BP; CPR, C-reactive protein; BMI, body mass index.

  • a Tubulointerstitial diseases include pyelonephritis, interstitial nephropathies, and cystic diseases.

  • b Multisystemic diseases include lupus, cryoglobulineamia, vasculitides, myeloma, and amyloidosis.