Table 2.

Characteristics of hospitalizations, for non-AKI hospitalizations, all AKI hospitalizations, and hospitalizations with AKI listed as the first discharge diagnosisa

Total CohortNon-AKI HospitalizationsAKI by ICD Code in
Any Position (all AKI)First Position (for AKI)
Percent of total hospitalizations97.2%2.8%0.6%
Mean length of stay, days5.514.69.7
Mean time since visit 4, days1647.72047.12096.6
High-risk hospitalization (%)b5.45.70.0
AKI first diagnosis code (%)0.022.8100.0
Received dialysis in hospital (%)1.912.823.2
In-hospital death (%)2.518.94.5
  • aFor the comparison of non-AKI hospitalizations to AKI hospitalizations, all P values <0.001 with the exception of % high-risk hospitalization (P = 0.8). For the comparison of AKI hospitalizations defined by ICD code in the first position to those defined by an ICD in any other position (not shown), all P values <0.001 with the exception of mean length of stay (P = 0.04) and mean time since visit 4 (P = 0.8).

  • bHigh-risk hospitalization defined as a hospitalization with an ICD-9 code for open heart surgery (including coronary bypass surgery) or percutaneous coronary intervention.