Acute renal failure (ARF) is on the increase in the United States, according to a study that researchers say provides the most accurate estimates of ARF incidence to date.
Nearly all previous studies of ARF relied on data from hospitalized patients. The new study examined changes in serum creatinine values in a large community-based sample of patients seeking usual care in a large integrated health-care delivery system.
The new analysis, led by Chi-yuan Hsu, MD, of the University of Cal-ifornia in San Francisco, and Alan S. Go, MD, of Kaiser Permanente of Northern California, examined data on 3,787,410 members of Kaiser Per-manente of Northern California. These members contributed nearly 16 million person-years of observation.
Between 1996 and 2003, the incidence of ARF not requiring dialysis rose from 322.7 to 522.4 per 100,000 person-years. The incidence of ARF requiring dialysis increased from 19.5 to 29.5 per 100,000 person-years. ARF both requiring and not requiring dialysis occurred more commonly in men than women.
The incidence of non-dialysis-requiring ARF for the period 1996-2003 was 443.1 per 100,000 person-years for men compared with 330.4 per 100,000 person-years for women. The incidence of ARF requiring dialysis during the same period was 29.2 per 100,000 person-years for men and 20 per 100,000 person-years for women.
Moreover, the incidence increased with increasing age. For ARF not requiring dialysis, the incidence rose from 78 per 100,000 person-years in those under age 50 to 320, 814.8, 1809.1, and 3545.4 per 100,000 person-years in subjects aged 50-59, 60-69, 70-79, and 80 years and older, respectively, according to a report in Kidney International (2007;72:208-212).
For ARF requiring dialysis, the incidence increased from 8.3 per 100,000 person-years to 27.8, 61.1, and 95.6 per 100,000 person-years for patients aged 50-59, 60-69, and 70-79, years, respectively. The incidence declined to 75.4 per 100,000 person-years for patients aged 80 years and older.
The investigators explained that the drop in the incidence of dialysis-requiring ARF in the 80-and-older group strongly suggests that these elderly patients are not protected from ARF, but rather “are far less likely to be prescribed, or to accept, acute dialysis.”
Dr. Hsu and colleagues observed that although historically more attention has been focused on dialysis-requiring ARF, their data indicate that the incidence of non-dialysis-requiring ARF is likely to be 10- to 20-fold higher, “which highlights its overall importance to individuals and to the public health.”
The researchers defined non-dialysis-requiring ARF as an increase in serum creatinine level of 0.5 mg/dL for patients with a baseline serum creatinine level of 1.9 mg/dL, 1.0 mg/dL for those with a baseline level of 2.0-4.9 mg/dL, and 1.5 mg/dL for subjects with a baseline level of 5.0 mg/dL or higher. The investigators identified cases of dialysis-requiring ARF among patients who were not on maintenance dialysis on admission but who received dialysis during that hospitalization.