Table 1.

Descending hierarchy to determine baseline creatinine. Rules in order of preference, 1 through 5.

Rule	Creatinine Available Prior to Admission	Baseline Creatinine
1	3 or more outpatient values available in 14–365 days prior to admission (PTA)	Mean of all outpatient values
2	2 outpatient values available in 14–365 days PTA + some prior inpatient values	Mean of 2 outpatient and lowest inpatient value
3	1 or fewer outpatient creatinine values in 14–365 days PTA but outpatient values available within 18 months PTA	Mean of all outpatient values
4	No outpatient creatinine values in 18 months PTA but patient had prior inpatient admissions	Mean of 3 lowest inpatient values
5	No prior inpatient or outpatient creatinine available	Creatinine at admission