Mild hyponatremia is associated with low skeletal muscle mass, physical function impairment, and depressive mood in the elderly

Table 4 Results of logistic regression analysis for predicting sarcopenia, skeletal muscle mass, and physical and cognitive functions

Dependent variables	Model 1			Model 2
Dependent variables	n	OR (95% CI)	p	n	OR (95% CI)	p
Sarcopenia	2244	2.2 (1.2–4.0)	0.008	2107	2.2 (1.1–4.4)	0.02
Low skeletal muscle mass index^a	2561	1.7 (1.0–3.0)	0.07	2411	1.6 (0.8–3.2)	0.2
Low muscle strength^b	2097	2.2 (1.1–4.4)	0.03	1968	1.9 (0.9–3.8)	0.09
Poor physical performance; Walking speed < 1 m/s	747	3.5 (1.0–13.0)	0.06	689	5.3 (1.1–25.4)	0.04
One-leg standing test < 15 s	2695	2.3 (1.1–4.8)	0.03	2541	2.5 (1.2–5.5)	0.02
Cognitive disturbance; MMSE < 24	3091	1.1 (0.7–1.9)	0.6	2912	1.1 (0.7–1.9)	0.7
Executive dysfunction; FAB < 12	1831	1.0 (0.5–2.3)	0.95	1722	0.9 (0.4–2.1)	0.8
Poor walking memory; Digit Span forward < 6	1883	0.9 (0.5–1.9)	0.8	1769	0.9 (0.4–1.9)	0.8
Poor walking memory; Digit Span backward < 4	1869	1.1 (0.5–2.1)	0.8	1755	1.0 (0.5–2.1)	0.96
Poor attention; the category fluency subtest of the HDS-R < 6	3088	1.1 (0.6–1.8)	0.8	2911	1.0 (0.6–1.7)	0.99
Memory disorder^c	1889	0.7 (0.3–1.5)	0.4	1772	0.8 (0.4–1.9)	0.7
Severe depression; GDS-15 ≥ 10	3078	2.7 (1.4–5.2)	0.004	2901	2.6 (1.3–5.2)	0.006

Model 1. Adjusted for age and sex
Model 2. In the binary logistic regression analysis, all variables were entered into the multivariable model (age, sex, body mass index, history of heart disease, diabetes, CKD, hearing impairment, diuretic use, antiepileptic use, NaSSA use, SSRI or SNRI use, benzodiazepine use, serum potassium, C-reactive protein, anemia, and hypothyroidism)
Abbreviations: CI Confidence interval, CKD Chronic kidney disease, FAB Frontal Assessment Battery, GDS-15 15-item Geriatric Depression Scale, HDS-R Hasegawa Dementia Rating Scale-Revised, MMSE Mini-Mental State Examination, NaSSA Noradrenergic and specific serotonergic antidepressant, OR Odds ratio, SNRI Serotonin noradrenaline reuptake inhibitor, SSRI Selective serotonin reuptake inhibitors, WMS-R Wechsler Memory Scale-Revised
^aLow skeletal muscle mass was defined as skeletal muscle mass index < 7.0 kg/m² in men and < 5.7 kg/m² in women
^bReduced grip strength was defined as < 28 kg for men and < 18 kg for women
^cRaw WMS-R II score ≤ 8/9 for > 16 years of education, ≤ 4/5 for 8–15 years of education, ≤ 2/3 for 0–7 years of education

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