Epidemiology of de novo acute renal failure in hospitalized African Americans: comparing community-acquired vs hospital-acquired disease.

BACKGROUND: The high incidence and prevalence of end-stage kidney disease among African Americans is well known, but the epidemiology of acute renal failure (ARF) among African Americans is unknown. This study was designed to determine the incidence, associated risk factors, and prognosis of ARF in hospitalized African Americans and to compare these variables in hospital-acquired ARF (HA-ARF) against community-acquired ARF (CA-ARF).

METHODS: A 3-year (1994-1996), computer-assisted retrospective analysis of hospital discharges with confirmed diagnoses of ARF. One hundred of 240 cases met the inclusion criteria for de novo ARF. Demographic, laboratory, and clinical profiles of all patients were retrieved and subdivided into CA-ARF and HA-ARF. Both analysis of variance and chi2 tests were used for analysis. Survival regression used both the Cox proportional hazards and Kaplan-Meier models.

RESULTS: The incidence of CA-ARF was 3.5 times greater than that of HA-ARF (0.55% vs 0.15%). The mean age of all patients was 54 years with a 67% male predominance. There were no significant differences in age, sex, peak serum creatinine levels, or underlying medical history. Prerenal causes of ARF were more common among CA-ARF than HA-ARF (35% vs 19%; P = .07), but intra-renal causes were more common among HA-ARF (81% vs 55%; P = .07). All cases of obstruction occurred in CA-ARF. Mortality was higher in HA-ARF (59% vs 33%; P = .03), and the incidence of recognized predictors of mortality was higher in patients with HA-ARF than in those with CA-ARF: oliguria (59% vs 35%; P = .04); sepsis (73% vs 35%; P = .004); stay in the intensive care unit (ICU) or mechanical ventilation (55% vs 6%; P<.001); and multiorgan failure (59% vs 24%; P = .002). Those with HA-ARF were twice as likely to require dialysis as those with CA-ARF. The mortality was high in younger patients with CA-ARF and in older patients with HA-ARF, but the dialysis-related mortality rate was 3-fold higher among patients with HA-ARF. While mean +/- SD length of hospital stay was more prolonged in HA-ARF than CA-ARF (26 +/- 28 days vs 12 +/- 11 days; P<.001), the 120-day survival rate was lower in HA-ARF than CA-ARF (43% vs 66%; P = .05). The HA-ARF status was associated with a relative risk of 2.5 (confidence interval, 1.1-5.5; P = .03) for shortened survival.

CONCLUSIONS: The overall epidemiologic characteristics of ARF among hospitalized African Americans seem to be comparable to those in whites, but the difference in incidence between CA-ARF and HA-ARF was much higher in African Americans. In view of the high mortality and morbidity rates associated with ARF and the fact that younger African American patients with CA-ARF were more likely to die than their older counterparts, we recommend that renal failure awareness be incorporated into community-based health educational programs in African American populations.