Table 1. Characteristics of the study population, weighted for the stratified sampling presented as mean (95% CI) or weighted n (%).
| Age | 65.1 (64.9, 65.3) |
| Sex | |
| Women | 15311 (55%) |
| Men | 12461 (45%) |
| Self-reported race | |
| Black | 11354 (41%) |
| White | 16418 (59%) |
| Region* | |
| Belt | 9757 (35%) |
| Buckle | 5197 (19%) |
| Non-Belt | 12818 (46%) |
| Annual Household Income | |
| < $20k | 4366 (16%) |
| $20k-$34k | 6460 (23%) |
| $35k-$75k | 8560 (31%) |
| >=$75k | 4788 (17%) |
| Refused | 3599 (13%) |
| Education | |
| < high school | 3468 (28%) |
| High school graduate | 6368 (23%) |
| Some college | 7758 (28%) |
| College graduate and above | 10178 (37%) |
| Season of Baseline Visit | |
| Winter | 6290 (23%) |
| Spring | 6011 (22%) |
| Summer | 7325 (26%) |
| Autumn | 8147 (29%) |
| Exercise | |
| None | 9306 (34%) |
| 1-3 times per week | 9950 (36%) |
| >3 times per week | 8246 (30%) |
| TV Watching | |
| None | 208 (1%) |
| 1-6 hrs/week | 3395 (15%) |
| 1 hr/day | 1237 (6%) |
| 2 hrs/day | 5478 (24%) |
| 3 hrs/day | 5222 (23%) |
| 4+ hrs/day | 6911 (31%) |
| Current Anti-hypertensive Meds | 13935 (52%) |
| Body Mass Index (kg/m2) | 29.1 (28.7, 29.5) |
| eGFR (ml/min/1.73m2)) | 85.9 (84.8, 87.0) |
| Serum Calcium (mg/dL) | 9.2 (9.1, 9.3) |
| Serum Phosphate (mg/dL) | 3.5 (3.45, 3.52) |
| Serum PTH (pg/mL) | 46.3 (44.4, 48.1) |
| Plasma FGF 23 (RU/ml) | 124 (96, 152) |
| Solar Insolation (8-week mean) (Kj/m2/day) | 17442 (17064, 17820) |
| Mean Temperature (8-week mean) (centigrade) | 16.7 (16.2, 17.3) |
| Plasma Vitamin D (25 OHD (ng/mL) | 25.8 (25.1, 26.4) |
| Systolic blood pressure (mmHg) | 127 (126, 128) |
| Diastolic blood pressure (mmHg) | 76.3 (75.6, 77.0) |
Participants lived between Lat.25.82°N-47.79°N and 69.78°W-122.86°W Long. Buckle refers to the following states: LA, MS, AL, AK, GA, NC, SC, and TN. Belt refers to the regions along the coasts of NC, SC, and GA. Differences in the total weighted n across different rows are due to missing data.
Abbreviations: eGFR: estimated glomerular filtration rate; PTH: parathyroid hormone: FGF23: fibroblast growth factor 23
Conversion to SI units: Calcium: mg/dl × 0.25= mM/L; Phosphorus: mg/dl × 0.323= mM/L; PTH: pg/ml × 2.5= ng/L.