Table 2.
Baseline Serum Sodium Concentrations and the Incidence of Blood Pressure Outcomes on Follow-up.
| Baseline | Follow-up | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Serum Sodium Categories | Men | Women | Mean Baseline Blood Pressure (mmHg) | Increase in Blood Pressure Stage* | Hypertension† | |||||
| n | Median serum Sodium, meq/L (minimum, maximum) | n | Median serum Sodium, meq/L (minimum, maximum) | Systolic | Diastolic | No. of events/No. at risk | % (95% CI)* | No. of events/No. at risk | % (95% CI)† | |
| First (lowest) | 227 | 136 (133–137) | 278 | 137 (133–137) | 115 | 75 | 197/505 | 39.0 (34.1, 44.1) | 76/505 | 15.1 (11.7, 19.1) |
| Second | 308 | 139 (138–139) | 366 | 138 (138–139) | 116 | 75 | 244/674 | 37.0 (32.6, 41.6) | 100/674 | 15.2 (12.1, 19.0) |
| Third | 162 | 140 (140–140) | 188 | 140 (140–140) | 117 | 76 | 123/350 | 35.5 (30.1, 41.2) | 54/350 | 15.7 (11.8, 20.5) |
| Fourth (highest) | 298 | 142 (141–145) | 345 | 142 (141–145) | 116 | 75 | 241/643 | 36.5 (32.1, 41.2) | 88/643 | 13.2 (10.3, 16.7) |
The 4 categories of serum sodium did not have equal numbers of participants (i.e., were not exact quartiles) because serum sodium concentrations were reported as whole numbers.
*
age- and sex-adjusted %; an increase in blood pressure stage was defined as an increment of at least one blood pressure category (as defined by the sixth report of the Joint National committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure).
†
age- and sex-adjusted %; Hypertension was defined as a systolic blood pressure of 140mm Hg or higher, a diastolic blood pressure of 90mm Hg or higher, or the use of antihypertensive medications.