National Analgesic Nephropathy Study

It has been proposed that the chronic, long-term ingestion of analgesics leads to specific renal pathology and renal failure. Previous studies suggested that the non–contrast-enhanced computerized tomography (CT) scan is a highly reliable tool for the diagnosis of analgesic-associated renal disease. The National Analgesic Nephropathy Study (NANS) is a case control study that was established to examine the association between heavy analgesic use and renal insufficiency and to investigate the ability of the CT scan to detect heavy analgesic use in the US population with end-stage renal disease (ESRD).

Patients with ESRD without a clear nonanalgesic cause for renal failure who had begun dialysis within the previous 3 months were enrolled in the study. A non-contract enhanced CT scan was performed using a standardized protocol. Three parameters—size, indentations, and calcifications—were used to identify patients who might have analgesic-induced kidney disease. Additionally, an interview was conducted to obtain information from patients concerning analgesic use, pre-dialysis signs and symptoms of renal disease, medical history, and demographics.

The study concluded that findings of small indented calcified kidneys (SICK) did not occur with sufficient frequency in US patients with ESRD and heavy analgesic exposure to render the non-contrast-enhanced CT scan a sensitive tool to identify such individuals. Although the conclusion concerning the lack of diagnostic value of the CT scan is clear, the study did not address the overall relationship between analgesics and the progression of renal disease. Results showed an association between heavy analgesic ingestion and findings of SICK in incident US patients with ESRD, which seemed to be accounted for mostly by phenacetin-containing products; however, future studies are needed to learn whether there is an association in the US population between currently available analgesics and ESRD and whether the ingestion of NSAID or cyclooxygenase-2 inhibitors contribute to the development of ESRD.