Baseline characteristics according to RLS status in the WHS (n=29 756)
| No RLS (n=26 269) | RLS (n=3487) | p Value | |
| Demographic information | |||
| Mean age, years (SD) | 63.4 (6.9) | 63.3 (6.8) | 0.30 |
| Ethnicity, n (%) | |||
| White | 24 786 (95.1) | 3376 (97.4) | <0.01 |
| Geographic location, n (%) | <0.01 | ||
| Northeast | 5168 (19.7) | 605 (17.4) | |
| Southeast | 5985 (22.8) | 825 (23.7) | |
| Midwest | 9362 (35.7) | 1312 (37.7) | |
| West | 5713 (21.8) | 742 (21.3) | |
| CVD risk factors, n (%) | |||
| History of hypertension | 12 273 (46.7) | 1759 (50.4) | <0.01 |
| History of diabetes | 1709 (6.5) | 295 (8.5) | <0.01 |
| History of cholesterol ≥240 mg/dl | 13 850 (52.8) | 2013 (57.8) | <0.01 |
| BMI categories (kg/m2) | <0.01 | ||
| <25 | 10 813 (41.8) | 1302 (37.8) | |
| 25–29.9 | 8866 (34.3) | 1195 (34.7) | |
| ≥30 | 6177 (23.9) | 950 (27.6) | |
| Smoking status | <0.01 | ||
| Never | 13 484 (52.0) | 1619 (47.0) | |
| Past | 10 352 (39.9) | 1504 (43.7) | |
| Current | 2083 (8.0) | 321 (9.3) | |
| Alcohol consumption | 0.05 | ||
| Rarely/never | 11 071 (42.4) | 1558 (44.9) | |
| 1–3 drinks per month | 3044 (11.7) | 394 (11.3) | |
| 1–6 drinks per week | 8969 (34.4) | 1138 (32.8) | |
| ≥1 drink/day | 2936 (11.2) | 314 (9.0) | |
| Exercise | <0.01 | ||
| Rarely/never | 9875 (37.6) | 1380 (39.6) | |
| <1/week | 5224 (19.9) | 728 (20.9) | |
| 1–3 times/week | 8225 (31.3) | 1064 (30.5) | |
| ≥4 times/week | 2939 (11.2) | 314 (9.0) | |
| Parental history of myocardial infarction | 4391 (16.8) | 646 (18.6) | <0.01 |
| Postmenopausal status | 0.13 | ||
| Premenopausal | 467 (1.8) | 54 (1.6) | |
| Postmenopausal | 23 368 (90.8) | 3082 (90.1) | |
| Biological uncertain | 1651 (6.4) | 253 (7.4) | |
| Unclear/subject unsure | 264 (1.0) | 33 (0.96) | |
| Postmenopausal hormone use | <0.01 | ||
| Never | 5626 (22.3) | 636 (18.9) | |
| Past | 6347 (25.2) | 836 (24.9) | |
| Current | 13 225 (52.5) | 1891 (56.2) | |
| Other covariates, n (%) | |||
| History of migraine | 5509 (21.0) | 909 (26.1) | <0.01 |
| History of depression | 3132 (11.9) | 707 (20.3) | <0.01 |
| History of Parkinson's disease | 105 (0.4) | 21 (0.6) | 0.08 |
| Iron supplementation use | 1028 (4.0) | 124 (3.6) | 0.30 |
| Being fatigued | 9101 (34.8) | 1776 (51.1) | <0.01 |
Percentages may not add up to 100% due to rounding or missing values.
BMI, body mass index; CVD, cardiovascular disease; RLS, restless legs syndrome; WHS, Women's Health Study.