Table 1.

Demographic characteristics for postmenopausal women with and without an incident kidney stone in the WHI Observational Study

CharacteristicNo Nephrolithiasis, n (%) (n=81,833 [97.2%])Incident Nephrolithiasis, n (%)
(n=2392 [2.8%])P Value
Demographics and history
 Age at enrollment 0.003
  50–59 yr26,247 (32)781 (33)0.58
  60–69 yr36,298 (44)1008 (42)
  ≥70 yr19,288 (24)603 (25)
  Mean±SD (yr)63.5±7.363.6±7.5
 Race/ethnicity<0.001
  White69,363 (85)1912 (80)
  Black5982 (7)232 (10)
  Hispanic2746 (3)120 (5)
  Asian or Pacific Islander2308 (3)67 (3)
  Native American325 (<1)16 (1)
  Other893 (1)34 (1)
 Baseline history of diabetes mellitus3910 (5)208 (9)<0.001
 Baseline supplemental calcium use20,373 (25)484 (21)<0.001
 Hormone replacement therapy<0.001
  None31,793 (40)957 (41)
  Prior11,802 (15)414 (18)
  Current36,530 (46)950 (41)
 BMI<0.001
  <18.5 kg/m2 (underweight)967 (1)16 (1)<0.001
  18.5–24.9 kg/m2 (normal weight)32,910 (41)718 (30)
  25–29.9 kg/m2 (overweight)27,567 (34)817 (34)
  30–34.9 kg/m2 (moderately obese)12,347 (15)486 (21)
  ≥35 kg/m2 (severely obese)7118 (9)333 (14)
  Mean±SD (kg/m2)27.1±5.828.8±6.5
 Household annual income<0.001
  <$50,00044,265 (57)1433 (62)
  ≥$50,00034,057 (43)866 (38)
 Geographical region0.03
  Northeast18,810 (23)557 (23)
  South20,802 (25)655 (27)
  Midwest18,267 (22)486 (20)
  West23,954 (29)694 (29)
 Study participation follow-up (yr)
  Mean±SD7.2±1.17.3±1.0<0.001
  Median (25th–75th percentile)8 (7–8)8 (7–8)<0.001
Physical activity and dietary energy intake
 Any physical activity70,542 (87)1927 (82)<0.001
 Physical activity <0.001
  Inactive10,391 (13)428 (18)<0.001
  0.1–4.9 METs/wk15,116 (19)519 (22)
  5–9.9 METs/wk13,666 (17)404 (17)
  10–19.9 METs/wk21,004 (26)524 (22)
  20–29.9 METs/wk10,847 (13)250 (11)
  ≥30 METs/wk9909 (12)230 (10)
  Mean±SD (METs/wk)14.0±14.411.8±13.6
 Raw energy intake<0.001
  <1800 kcal/d59,958 (73)1683 (70)<0.001
  1800–1999 kcal/d7294 (9)197 (8)
  2000–2199 kcal/d4984(6)156 (7)
  2200–2499 kcal/d4511 (6)139 (6)
  ≥2500 kcal/d5086 (6)217 (9)
  Mean±SD (kcal/d)1529±5871574±679
 Calibrated energy intake<0.001
  <1800 kcal/d2064 (3)60 (3)<0.001
  1800–1999 kcal/d19,288 (15)491 (22)
  2000–2199 kcal/d33,822 (44)869 (39)
  2200–2499 kcal/d17,774 (23)651 (29)
  ≥2500 kcal/d3434 (5)163 (7)
  Mean±SD (kcal/d)2118±2062157±235
  • Unless otherwise noted, values are the number (percentage) of participants.