Change in renal function after sodium phosphate preparation for screening colonoscopy

Table 1 Baseline characteristics of subjects in the NaP, PEG and control groups n (%)

Characteristics	NaP group (n = 224)	PEG group (n = 113)	Control group (n = 672)	P
Age (yr)	46.9 ± 8.6	51.1 ± 10.5	46.9 ± 8.6	< 0.001
Gender				0.453
Male	149 (67)	81 (72)	475 (71)
Female	75 (33)	32 (28)	197 (29)
Body mass index (kg/m2)	23.4 ± 3.1	23.8 ± 2.7	23.6 ± 2.9	0.496
Hypertension	50 (22)	34 (30)	188 (28)	0.186
Diabetes mellitus	29 (13)	23 (20)	134 (20)	0.056
Serum phosphate1 (mg/dL)	88.9 ± 14.5	95.3 ± 17.4	91.6 ± 17.4	0.004

¹Measured in 94 subjects in the sodium phosphate (NaP) group, 87 subjects in the polyethylene glycol (PEG) group, and 219 subjects in the control group.

Table 2 Comparison of the creatinine level and glomerular filtration rate (GFR) among NaP, PEG and control groups (mean  ±  SD)

Evaluation time	Creatinine level (mg/dL)				GFR (mL/min per 1.73 m2)
	NaP group	PEG group	Control group	P	NaP group	PEG group	Control group	P
Baseline	1.12 ± 0.15	1.12 ± 0.16	1.12 ± 0.15	0.985	69.03 ± 7.74	68.91 ± 7.95	69.57 ± 6.67	0.467
Follow-up 12–24 mo later	1.15 ± 0.15	1.15 ± 0.18	1.15 ± 0.15	0.928	66.46 ± 7.78	66.47 ± 8.26	67.42 ± 6.39	0.118

Table 3 Multivariate linear regression model on change in creatinine and GFR from baseline to 12-24 mo

Variable	Creatinine (R2 = 0.016)		GFR (R2 = 0.053)
	Correlation coefficient (95% CI)	P	Correlation coefficient (95% CI)	P
Baseline	-0.018 (-0.057 to 0.021)	0.366	-0.135 (-0.187 to -0.083)	< 0.001
Group effect (NaP, PEG and control groups)	0.002 (-0.004 to 0.009)	0.489	-0.247 (-0.685 to 0.191)	0.269
Age at baseline creatinine and GFR measurement	0.000 (0.000 to 0.001)	0.433	-0.036 (-0.077 to 0.006)	0.094
Hypertension	0.007 (-0.009 to 0.023)	0.365	-0.748 (-1.774 to 0.277)	0.152
Diabetes mellitus	-0.016 (-0.034 to 0.002)	0.079	1.082 (-0.076 to 2.240)	0.067
Body mass index	0.001 (-0.001 to 0.003)	0.208	-0.038 (-0.162 to 0.086)	0.545
Serum phosphate	-0.001 (-0.004 to 0.003)	0.733	0.020 (-0.205 to 0.246)	0.859

Table 4 Description of the design, demographic characteristics, and effect estimate in previous studies

	Design	Population	Race (%)	Control	Timing of Follow-up	Association between NaP exposure and incident kidney injury
Abaskharoun et al[9]	RC	Any patients who had outpatient CFS	Not reported	PEG	3 mo-9 yr	No
Brunelli et al[10]	CC	Any patients who had outpatient CFS	White 46%, Non-white 52%, Unknown 2.3%	Any non-NaP preparation	Within 6 mo	No
Hurst et al[11]	RC	Any patients who had screening CFS	White 54%, Black 19%, Unknown 27%	PEG	Within 1 yr	Yes
Khurana et al[12]	RC	Any patients1	White 84%, Black 8%, Hispanic 7%, Asian 0.5%	No bowel preparation	6-9 mo/ 12-18 mo	Yes
Russmann et al[13]	RC	Any patients who had CFS	Not reported	PEG	Within 6 mo	No
Singal et al[14]	RC	Any patients who had CFS	White 27%, Black 53%, Hispanic 20%, Asian 0.3%	PEG	Within 1 yr	Yes

¹Excluded patients who had acute colonoscopic indication or systemic conditions which affect the renal functional deterioration. RC: Retrospective cohort; CFS: Colonofiberoscopy; CC: Case-control.