Table 1.

Demographic and clinical characteristics of participants

CharacteristicPrimary CohortLaboratory Cohort
StoneNo StoneP ValueStoneNo StoneP Value
Patients (n)25,5323,169,92013,2621,989,792
Age (yr)46 (34.8,60.2)35.1 (23,48.4)<0.00152.7 (41.7,65.3)46.3 (34.2,58.5)<0.001
Men16,361 (64.1)1,598,312 (50.4)<0.0018422 (63.5)886,774 (44.6)<0.001
Aboriginal568 (2.2)87,941 (2.8)<0.001293 (2.2)48,737 (2.4)0.08
Social assistance968 (3.8)83,528 (2.6)<0.001535 (4)59,377 (3)<0.001
Residencea<0.001<0.001
 ≤50 km17,201 (67.4)2,303,140 (72.7)9306 (70.2)1,491,766 (75)
 50.1–200 km5612 (22)538,693 (17)2618 (19.7)313,192 (15.7)
 >200 km2719 (10.6)328,087 (10.4)1338 (10.1)184,834 (9.3)
Comorbid conditions
 AIDS/HIV21 (0.1)1138 (0)<0.00115 (0.1)1533 (0.1)0.14
 Cancer1108 (4.3)65,469 (2.1)<0.001925 (7)76,171 (3.8)<0.001
 Cerebral vascular disease586 (2.3)37,922 (1.2)<0.001453 (3.4)42,236 (2.1)<0.001
 COPD4441 (17.4)391,613 (12.4)<0.0012426 (18.3)265,908 (13.4)<0.001
 CHDb325 (1.3)14,078 (0.4)<0.001668 (5)49,360 (2.5)<0.001
 Dementia116 (0.5)17,097 (0.5)0.07140 (1.1)22,350 (1.1)0.46
 Diabetes1589 (6.2)82,682 (2.6)<0.0011835 (13.8)133,808 (6.7)<0.001
 Heart failure586 (2.3)41,204 (1.3)<0.001543 (4.1)44,471 (2.2)<0.001
 Hypertension4140 (16.2)255,621 (8.1)<0.0014425 (33.4)429,520 (21.6)<0.001
 Mild liver disease226 (0.9)15,052 (0.5)<0.001191 (1.4)16,638 (0.8)<0.001
 Moderate/severe liver disease27 (0.1)1494 (0)<0.00120 (0.2)1792 (0.1)0.02
 Paraplegia240 (0.9)10,419 (0.3)<0.001146 (1.1)7669 (0.4)<0.001
 PVD409 (1.6)23,619 (0.7)<0.001331 (2.5)25,146 (1.3)<0.001
 Peptic ulcer1205 (4.7)72,530 (2.3)<0.001432 (3.3)39,480 (2)<0.001
 Rheumatologic disease344 (1.3)23,219 (0.7)<0.001264 (2)22,853 (1.1)<0.001
 Charlson comorbidity scorec 0 (0,1)0 (0,0)<0.0010 (0,1)0 (0,1)<0.001
eGFR<0.001
 ≥60 ml/min per 1.73 m211,645 (87.8)1,854,612 (93.2)
 45–59.9 ml/min per 1.73 m21071 (8.1)92,869 (4.7)
 30–44.9 ml/min per 1.73 m2415 (3.1)32,528 (1.6)
 15–29.9 ml/min per 1.73 m2131 (1)9783 (0.5)
Albuminuria<0.001
 None10,574 (79.7)1,829,246 (91.9)
 Mild2221 (16.7)139,820 (7)
 Heavy467 (3.5)20,726 (1)
  • Unless otherwise noted, values are expressed as number (percentage) of patients or median (interquartile range) where appropriate. COPD, chronic obstructive pulmonary disease; CHD coronary heart disease; PVD, peripheral vascular disease; eGFR, estimated glomerular filtration rate using the CKD-Epidemiology Collaboration formula.

  • a Residence is distance in kilometers to the nearest nephrologist, used as a proxy for access to specialty medical care.

  • b Coronary heart disease includes acute myocardial infarction, percutaneous transluminal coronary angioplasty, and coronary artery bypass graft.

  • c Charlson score includes AIDS/HIV, metastatic cancer, nonmetastatic cancer, cerebral vascular disease, chronic obstructive pulmonary disease, dementia, diabetes, heart failure, mild liver disease, moderate/severe liver disease, myocardial infarction, paraplegia, peptic ulcer, peripheral vascular disease, and rheumatologic disease.