Table 3. Estimated hospital costs per patient between randomisation and two months follow-up.

	Sodium bicarbonate N = 168		Saline N = 165		Mean difference in $ (95% CI)
	Volume*	Mean cost in $ (SD)	Volume*	Mean cost in $ (SD)
Costs related to contrast procedure
- infusion fluids	0.96	4 (1)	0.96	3 (1)	1 (1 to 1)
- days prior to contrast exposure	0.52	394 (527)	0.93	705 (344)	-311 (-407 to -215)
- day of contrast exposure1	0.96	678 (178)	0.96	727 (149)	-48 (-84 to -13)
- day following contrast exposure2	0.11	82 (236)	0.17	126 (284)	-45 (-101 to 12)
- ICU days due to hydration complications†	0.00	0 (0)	0.01	38 (485)	-38 (-111 to 36)
- non-ICU days due to hydration complications†	0.0	0 (0)	0.12	93 (941)	-93 (-236 to 49)
- total costs related to the contrast procedure		1158 (650)		1561 (522)	-403 (-530 to -275)
Other hospitalization
- following contrast exposure3	1.86	1414 (4458)	1.23	934 (3228)	480 (-363 to 1324)
- day care	0.14	69 (255)	0.17	80 (235)	-11 (-64 to 42)
- non-ICU, AKI4	0.00	0 (0)	0.08	61 (775)	-61 (-178 to 57)
- non-ICU, non-AKI4	1.97	1500 (4815)	2.11	1607 (4123)	-107 (-1077 to 864)
- ICU4	0.08	258 (2477)	0.04	133 (1698)	125 (-335 to 586)
Outpatient visits
- emergency department	0.09	22 (75)	0.10	24 (83)	-2 (-19 to 15)
- nephrology	0.32	45 (119)	0.25	34 (100)	11 (-13 to 34)
- non-nephrology	2.84	395 (441)	3.28	456 (494)	-62 (-163 to 40)
Total costs		4861 (7313)		5022 (6254)	-161 (-1634 to 1312)

Abbreviations: ICU = intensive care unit, AKI = acute kidney injury

* Volumes represent percentage of patients or mean number of procedures, hospital days or visits

^† i.e. acute heart failure due to volume overload

¹ Costs based on prices for either day-care or non-ICU days depending on duration of hospitalisation,

² Only in those discharged on the day following the contrast procedure,

³ Excluding the day following contrast exposure in patients discharged on that following day,

⁴ Hospitalization not directly following contrast exposure