Table 2.
Characteristics of the Participants and Households at Enrollment
| Characteristics | Drinking Water Electrical Conductivity (EC) Categories | |||||
|---|---|---|---|---|---|---|
| Fresh Water (EC <0.7 mS/cm, n=547) | P Value | Mild‐Salinity Water (EC: 0.7 to <2 mS/cm, n=523) | P Value | Moderate‐Salinity Water (EC: 2–10 mS/cm, n=503) | P Value | |
| Age (y), median (IQR) | 40 (31–54) | Ref | 41 (30–54) | 0.900 | 40 (30–54) | 0.672 |
| Age categories, % (n) | ||||||
| 20 to <30 y | 21 (117) | Ref | 23 (122) | 0.709 | 22 (110) | 0.855 |
| 30 to <40 y | 27 (150) | Ref | 25 (130) | 0.704 | 27 (137) | 1.000 |
| 40 to <50 y | 20 (112) | Ref | 20 (105) | 1.000 | 21 (105) | 0.855 |
| 50 to <60 y | 15 (82) | Ref | 16 (82) | 0.860 | 17 (87) | 0.723 |
| 60 to <70 y | 11 (58) | Ref | 10 (54) | 0.863 | 9 (43) | 0.742 |
| ≥70 y | 5 (28) | Ref | 6 (30) | 0.868 | 4 (21) | 0.868 |
| Male sex, % (n) | 41 (226) | Ref | 41 (214) | 1.000 | 40 (203) | 0.833 |
| BMI, median (IQR) | 22.3 (19.5–25) | Ref | 21.6 (19.4–23.9) | 0.006 | 21.4 (18.9–23.9) | <0.001 |
| WHO BMI categories, % (n) | ||||||
| Underweight (<18.5) | 15 (79) | Ref | 16 (81) | 0.861 | 19 (94) | 0.487 |
| Normal weight (18.5 to <25) | 59 (317) | Ref | 67 (339) | 0.034 | 64 (321) | 0.194 |
| Overweight (≥25 to <30) | 22 (118) | Ref | 15 (75) | 0.229 | 14 (71) | 0.175 |
| Obese (≥30) | 4 (23) | Ref | 3 (14) | 0.875 | 3 (13) | 0.877 |
| Smoking categories, % (n) | ||||||
| Never | 54 (294) | Ref | 49 (258) | 0.241 | 53 (267) | 0.813 |
| Former | 9 (47) | Ref | 12 (61) | 0.617 | 8 (40) | 0.868 |
| Current | 38 (206) | Ref | 39 (204) | 0.835 | 39 (196) | 0.837 |
| WHO work‐related physical activity, % (n) | ||||||
| Sedentary | 37 (205) | Ref | 42 (219) | 0.293 | 12 (59) | <0.001 |
| Moderatea | 39 (215) | Ref | 34 (178) | 0.306 | 71 (355) | <0.001 |
| Vigorousb | 23 (127) | Ref | 24 (126) | <0.834 | 18 (89) | 0.334 |
| Urinary creatinine (mg/day), median (IQR) | ||||||
| Male | 1547 (1164–1951) | Ref | 1471 (1123–1775) | 0.051 | 1409 (1092–1787) | 0.004 |
| Female | 1209 (948–1522) | Ref | 1107 (881–1390) | 0.012 | 1103 (928–1307) | <0.001 |
| Household wealth categories, % (n) | ||||||
| Lowest | 14 (35) | Ref | 18 (44) | 0.016 | 29 (64) | 0.093 |
| Second | 14 (35) | Ref | 23 (55) | 0.294 | 23 (51) | 0.299 |
| Third | 18 (45) | Ref | 23 (55) | 0.540 | 19 (41) | 0.905 |
| Fourth | 23 (56) | Ref | 21 (51) | 0.803 | 16 (34) | 0.424 |
| Highest | 31 (75) | Ref | 15 (36) | 0.071 | 14 (30) | 0.073 |
| Added table salt with food | 59 (322) | Ref | 71 (370) | 66 (333) | ||
| Added table salt during cookingc % (n) | 100 (473) | Ref | 100 (497) | 1.000 | 100 (220) | 1.000 |
| Hours of sleep, % (n) | ||||||
| <6 h | 18 (96) | Ref | 24 (126) | 0.143 | 17 (86) | 0.856 |
| ≥6 to <9 h | 72 (395) | Ref | 61 (318) | 0.002 | 71 (357) | 0.762 |
| ≥9 h | 10 (56) | Ref | 15 (79) | 0.394 | 12 (60) | 0.731 |
| Alcohol consumption, % (n) | 4 (22) | Ref | 3 (15) | 0.873 | 4 (19) | 1.000 |
| Religion, % (n) | ||||||
| Hindu | 53 (289) | Ref | 55 (287) | 0.630 | 46 (233) | 0.112 |
| Muslim | 47 (258) | Ref | 45 (236) | 0.656 | 54 (270) | 0.108 |
| Self‐reported disease, % (n) | ||||||
| Hypertension | 18 (100) | Ref | 12 (61) | 0.310 | 15 (74) | 0.600 |
| Diabetes mellitus | 5 (29) | Ref | 4 (22) | 0.866 | 5 (23) | 1.000 |
| Chronic kidney disease | 2 (13) | Ref | 2 (11) | 1.000 | 2 (12) | 1.000 |
| Volume of 24‐h urine, median (IQR)d | 2224 (1655–2861) | Ref | 2030 (1515–2742) | 0.045 | 2026 (1323–2530) | <0.001 |
BMI indicates body mass index; EC, electrical conductivity; IQR, interquartile range; WHO, World Health Organization.
Work involves moderate‐intensity activity that causes small increases in breathing or heart rate such as brisk walking (or carrying light loads) for at least 10 minutes continuously.
Work involves vigorous‐intensity activity that causes large increases in breathing or heart rate (carrying or lifting heavy loads, digging or construction work) for at least 10 minutes continuously.
Data on use of salt during cooking were measured during the randomized‐controlled trial only. However. All households reported use of table salt during cooking, so this variable was not used for model adjustment.
We noticed participants 24‐hour volume changed across different visits or seasons. Median 24‐hour urine volume was highest (2224 mL) during December (visit 1 of the stepped‐wedge trial), and the lowest (1764) during April (visit 5 of the stepped‐wedge trial). Median 24‐hour urine volume was 2222 mL, 2176 mL, and 1994 during January (visit 2), February (visit 3), and March (visit 4) in stepped‐wedge trail.