Table 2.

Simple and multiple linear regression analyses of the variables correlated with HCO₃⁻ concentration

Variable	Simple linear regression analysis		Multivariate linear regression analysis
	Coefficient (β)	P value	Coefficient (β)	Standard coefficient	P value
Constant			23.070
Age (yr)	−0.036	0.017	−0.005	−0.019	0.50
Male (yes vs. no)	−0.913	0.08
Body mass index (kg/m2)	−0.060	0.18
Diabetes mellitus (yes vs. no)	0.105	0.83
Corticosteroid (yes vs. no)	2.261	< 0.001	−0.011	−0.001	0.97
β-blocker (yes vs. no)	−0.878	0.11
Renin–angiotensin system inhibitor (yes vs. no)	−1.568	0.002	0.015	0.002	0.94
Aldosterone receptor antagonist (yes vs. no)	2.857	0.033	−0.185	−0.008	0.73
Loop diuretic (yes vs. no)	0.081	0.87
Thiazide diuretic (yes vs. no)	0.450	0.54
Sodium bicarbonate (yes vs. no)	−3.287	< 0.001	−0.455	−0.043	0.08
Potassium binder (yes vs. no)	−1.889	0.007	0.022	0.002	0.94
Phosphate binder (yes vs. no)	−3.472	< 0.001	0.298	0.019	0.45
Total protein (g/dL)	1.009	0.003
Serum albumin (g/dL)	1.464	< 0.001	−0.559	−0.077	0.006
Hemoglobin (g/dL)	0.800	< 0.001	0.078	0.042	0.19
Blood urea nitrogen (mg/dL)	−0.050	< 0.001	−0.012	−0.080	0.06
Creatinine (mg/dL)	−0.702	< 0.001
Estimated glomerular filtration rate (mL/min/1.73 m2)	0.047	< 0.001	−0.009	−0.069	0.047
Uric acid (mg/dL)	−0.052	0.28
Sodium (mmol/L)	−0.011	0.89
Potassium (mmol/L)	−3.587	< 0.001	−0.227	−0.029	0.28
Chloride (mmol/L)	−0.480	< 0.001	−0.145	−0.172	< 0.001
Total calcium (mg/dL)	2.360	< 0.001	0.133	0.024	0.42
Phosphate (mg/dL)	−1.240	< 0.001	−0.064	−0.020	0.59
Magnesium (mg/dL)	0.154	0.83
Blood glucose (mg/dL)	−0.011	0.047	−0.007	−0.072	0.004
Serum total CO2 (mmol/L)	1.009	< 0.001	0.859	0.777	< 0.001

CO₂, carbon dioxide; HCO₃⁻, bicarbonate ion.