Table 1.

Baseline characteristics of patients by risk group for hydronephrosis

	High risk (%, n=111)	Medium risk (%, n=76)	Low risk (%, n=94)	P value
Sociodemographics
Age
18–39	9	7	12	0.30
40–59	19	22	31
60–74	37	42	33
≥75	35	29	24
Sex
Male	64	51	53	0.15
Female	36	49	47
Race/ethnicity
Non-Hispanic white	34	24	11	<0.001*
Non-Hispanic black	14	39	63
Hispanic	32	29	22
Other	20	8	4
Risk criteria
History of hydronephrosis	27	0	0	<0.001*
Non-black race	86	61	37	<0.001*
History of recurrent UTIs	18	3	1	<0.001*
Diagnosis consistent with possible obstruction	70	45	16	<0.001*
Absence of nephrotoxins	68	39	10	<0.001*
Absence of CHF	92	86	44	<0.001*
Absence of prerenal AKI	78	67	53	0.005*
Laboratory results
Creatinine at admission, mean (SD)	4.2 (4.1)	3.7 (3.9)	3.0 (2.3)	0.048*
Baseline creatinine, mean (SD)	2 (1.5)	1.8 (1.3)	1.6 (0.9)	0.078

χ² tests were used to compare whether categorical variables differed by risk group for hydronephrosis. Analysis of variance tests were used to compare whether continuous variables (laboratory values) differed by risk group for hydronephrosis.

*Statistically significant at p<0.05.

AKI, acute kidney injury; CHF, congestive heart failure; UTIs, urinary tract infections.