Table 3.

Baseline characteristics of study participants for cognitive decline (longitudinal) analysis by tertiles of baseline serum sodium levels

Variable	Tertile 1 (126–140 mmol/L) (n=1175)	Tertile 2 (141–142 mmol/L) (n=1214)	Tertile 3 (143–153 mmol/L) (n=1222)
Age, yr	72±5	72±5	73±5
Race (% white)a	92	93	95
Education
High school or less	18	19	21
Some college	23	23	22
College	19	19	20
Some graduate school	12	13	12
Graduate school	28	26	26
Smoking
Never smoker	38	39	40
Current smoker	4	2	3
Former smoker	58	39	58
Alcohol, ≥12 drinks in past 12 mo	71	68	68
BMI category
Underweight	0.2	0.1	0.1
Normal weight	28	26	24
Overweight	50	51	55
Obese	21	23	21
Physical activity score	155±69	153±66	152±66
CKD-EPI eGFR, ml/min per 1.73 m2	77±14	76±14	76±14
Serum glucose, mg/dla	107±28	105±22	103±18
CVD	20	20	20
Diabetesa	11	9	7
Hypertensiona	44	38	40
Stroke	4	4	4
COPD	9	10	10
Excellent or good health status	89	91	89
SF-12 MCS score	56.1±6.6	56.2±6.2	56.2±5.9
Thiazide diuretic usea	14	11	10
3MS score	95±4	95±4	95±3
Trails B time, s	116±39	115±38	115±36
Serum sodium, mmol/La	139±2; 139 (138, 140)	142±1; 142 (141, 142)	144±1; 144 (143, 145)

Data are mean±SD, median (interquartile range), or %. Serum glucose is missing in n=81, thiazide diuretic use is missing for n=150, and change in Trails B time is missing for n=28. P values are comparisons across tertiles made using a chi-squared test for categoric data and ANOVA for continuous variables. BMI, body-mass index; CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; CVD, cardiovascular disease; COPD, chronic obstructive pulmonary disease; SF-12 MCS score, Medical Outcomes Study 12-Item Short Form Mental Health Composite Score (health-related quality of life); 3MS, modified Mini-Mental Status examination; Trails B, Trail Making Test Part B.

^aP<0.05 across tertiles by chi-squared test for categoric data and ANOVA for continuous variables.