Table 1.
Demographic characteristics for postmenopausal women with and without an incident kidney stone in the WHI Observational Study
| Characteristic | No 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 yr | 26,247 (32) | 781 (33) | 0.58 |
| 60–69 yr | 36,298 (44) | 1008 (42) | |
| ≥70 yr | 19,288 (24) | 603 (25) | |
| Mean±SD (yr) | 63.5±7.3 | 63.6±7.5 | |
| Race/ethnicity | <0.001 | ||
| White | 69,363 (85) | 1912 (80) | |
| Black | 5982 (7) | 232 (10) | |
| Hispanic | 2746 (3) | 120 (5) | |
| Asian or Pacific Islander | 2308 (3) | 67 (3) | |
| Native American | 325 (<1) | 16 (1) | |
| Other | 893 (1) | 34 (1) | |
| Baseline history of diabetes mellitus | 3910 (5) | 208 (9) | <0.001 |
| Baseline supplemental calcium use | 20,373 (25) | 484 (21) | <0.001 |
| Hormone replacement therapy | <0.001 | ||
| None | 31,793 (40) | 957 (41) | |
| Prior | 11,802 (15) | 414 (18) | |
| Current | 36,530 (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±5.8 | 28.8±6.5 | |
| Household annual income | <0.001 | ||
| <$50,000 | 44,265 (57) | 1433 (62) | |
| ≥$50,000 | 34,057 (43) | 866 (38) | |
| Geographical region | 0.03 | ||
| Northeast | 18,810 (23) | 557 (23) | |
| South | 20,802 (25) | 655 (27) | |
| Midwest | 18,267 (22) | 486 (20) | |
| West | 23,954 (29) | 694 (29) | |
| Study participation follow-up (yr) | |||
| Mean±SD | 7.2±1.1 | 7.3±1.0 | <0.001 |
| Median (25th–75th percentile) | 8 (7–8) | 8 (7–8) | <0.001 |
| Physical activity and dietary energy intake | |||
| Any physical activity | 70,542 (87) | 1927 (82) | <0.001 |
| Physical activity | <0.001 | ||
| Inactive | 10,391 (13) | 428 (18) | <0.001 |
| 0.1–4.9 METs/wk | 15,116 (19) | 519 (22) | |
| 5–9.9 METs/wk | 13,666 (17) | 404 (17) | |
| 10–19.9 METs/wk | 21,004 (26) | 524 (22) | |
| 20–29.9 METs/wk | 10,847 (13) | 250 (11) | |
| ≥30 METs/wk | 9909 (12) | 230 (10) | |
| Mean±SD (METs/wk) | 14.0±14.4 | 11.8±13.6 | |
| Raw energy intake | <0.001 | ||
| <1800 kcal/d | 59,958 (73) | 1683 (70) | <0.001 |
| 1800–1999 kcal/d | 7294 (9) | 197 (8) | |
| 2000–2199 kcal/d | 4984(6) | 156 (7) | |
| 2200–2499 kcal/d | 4511 (6) | 139 (6) | |
| ≥2500 kcal/d | 5086 (6) | 217 (9) | |
| Mean±SD (kcal/d) | 1529±587 | 1574±679 | |
| Calibrated energy intake | <0.001 | ||
| <1800 kcal/d | 2064 (3) | 60 (3) | <0.001 |
| 1800–1999 kcal/d | 19,288 (15) | 491 (22) | |
| 2000–2199 kcal/d | 33,822 (44) | 869 (39) | |
| 2200–2499 kcal/d | 17,774 (23) | 651 (29) | |
| ≥2500 kcal/d | 3434 (5) | 163 (7) | |
| Mean±SD (kcal/d) | 2118±206 | 2157±235 |
Unless otherwise noted, values are the number (percentage) of participants.