Table 2.

Baseline associations of serum and dialysate electrolytes with QTc interval in 330 incident dialysis patients

Variables	Model 1		Model 2		Model 3
	QTc difference (95% CI), ms	P	QTc difference (95% CI), ms	P	QTc difference (95% CI), ms	P
Serum measurements
Total calcium, per 1 mg/dl decrease	+ 3.23 (−4.44, 10.89)	0.41	+ 4.46 (− 2.84, 11.75)	0.23	+ 2.70 (− 4.67, 10.06)	0.47
Corrected calcium, per 1 mg/dl decrease	+ 2.27 (−6.48, 11.03)	0.61	+ 3.46 (− 4.89, 11.80)	0.42	+ 1.56 (− 6.65, 9.77)	0.71
Ionized calciuma, per 0.1 mmol/l decrease	+ 9.77 (2.97, 16.57)	0.01	+ 10.32 (3.87, 16.78)	0.002	+ 8.55 (2.13, 14.97)	0.01
Potassium, per 1 mEq/l decrease	+ 11.08 (2.18, 19.98)	0.02	+ 10.97 (2.50, 19.43)	0.01	+ 9.89 (1.58, 18.20)	0.02
Magnesiuma, per 0.1 mEq/l decrease	+ 0.34 (− 1.73, 2.40)	0.75	+ 0.35 (− 1.61, 2.31)	0.73	− 0.21 (− 2.13, 1.72)	0.83
Dialysate measurements
Calcium
2.5 mEq/l	reference		reference		reference
< 2.5 mEq/l	+ 1.27 (− 8.70, 11.24)	0.80	− 0.90 (− 10.55, 8.74)	0.86	+ 0.95 (− 8.52, 10.42)	0.84
Potassium
2 mEq/l	reference		reference		reference
> 2 mEq/l	−2.73 (− 16.96, 11.49)	0.71	−3.53 (− 17.01, 9.94)	0.61	−3.98 (− 17.16, 9.21)	0.56
Serum-to-dialysate gradients
Total calcium, per 1 mEq/l increase in difference	−3.33 (− 15.22, 8.55)	0.58	−6.84 (− 18.30, 4.62)	0.24	− 3.04 (− 14.57, 8.49)	0.61
Corrected calcium, per 1 mEq/l increase in difference	− 1.81 (− 14.66, 11.03)	0.78	− 5.40 (− 17.82, 7.02)	0.40	− 1.44 (− 13.72, 10.83)	0.82

Model 1 includes the main exposure (one of serum, dialysate, or gradient measurements)

Model 2 includes model 1, age, sex, and ethnicity

Model 3 includes model 2, Charlson comorbidity index, non-dialysis systolic blood pressure, left ventricular mass index, and use of antihypertensive medication, renin-angiotensin-aldosterone system blockade, cinacalcet, and QT-prolonging medication

^aModels with ionized calcium and magnesium also include serum pH