Table 1.

Characteristics of study participants by cohort

HPFS (n = 1032)NHS I (n = 1239)NHS II (n = 1077)
Age (yr)63.4 (58.8–69.3)66.2 (61.3–71.5)49.6 (45.1–53.8)
BMI (kg/m2)25.8 (23.7–28.0)26.0 (22.9–29.8)25.4 (22.5–30.7)
History of kidney stones (%)62.769.162.9
History of hypertension (%)35.649.022.2
History of diabetes (%)5.89.84.5
Family history of kidney stones (%)18.0NA25.3
Dietary oxalate (mg/d)190 (141–246)156 (116–201)160 (117–218)
Dietary calcium (mg/d)769 (627–976)733 (572–950)824 (661–1071)
Supplemental calcium (mg/d)0 (0–200)401 (0–950)200 (0–700)
Total vitamin C intake (mg/d)239 (148–614)203 (135–477)165 (108–276)
Urinary potassium (mEq/d)73 (58–91)58 (45–72)52 (41–66)
Urinary magnesium (mg/d)118 (94–147)95 (74–122)94 (74–121)
Urinary phosphate (mg/d)1033 (852–1249)729 (591–897)807 (649–999)
Urinary sodium (mEq/d)173 (134–224)132 (99–172)144 (109–182)
Urinary creatinine (mg/d)1633 (1384–1900)1029 (881–1185)1168 (1016–1359)
Urinary oxalate (mg/d)39 (31–47)27 (22–33)26 (21–32)
  • Data are presented as median (25th to 75th percentile) unless otherwise indicated. HPFS, Health Professionals Follow-up Study; NHS, Nurses’ Health Study; BMI, body mass index; NA, not applicable.