Non-phenacetin analgesics and analgesic nephropathy: clinical assessment of high users from a case-control study.

BACKGROUND: A recent large-scale case-control study on analgesic nephropathy (SAN) [1] found no increased risk of end-stage renal disease (ESRD) in users of combined or single formulations of phenacetin-free analgesics. In a subgroup of 22 high users, however, a dose-dependent increased risk was found, which raised the question if these patients presented or not with analgesic nephropathy (AN). METHODS: The individual questionnaires of this subgroup of high users were reviewed, and the total lifetime intake of different types of analgesics was calculated. For evidence of AN, the following data were considered: (1) the amount and type of analgesics consumed, (2) the cause of ESRD, as diagnosed by the nephrologist in charge of the patient and (3) renal imaging and other relevant laboratory data. RESULTS: This group of ESRD patients consumed on average 7.8 kg of antipyretic analgesics (range 30.8-2.7 kg) over an average of 21.5 years (range 35-6 years). Single analgesics were exclusively used by 12 patients (54.5%) and combined analgesics by 5 patients (22.7%), while 5 patients used both. None of the patients was diagnosed as having AN, and a review of the questionnaires did not disclose evidence suggestive of AN. The possibility that, irrespective of AN, the analgesic (ab)use contributed to the progression of existing renal diseases cannot be answered in the absence of well-defined criteria. The data supporting the existence of such an analgesic-associated nephropathy (AAN) are, however, not consistent and most likely due to confounding by indication. CONCLUSION: In a group of ESRD patients with high use of non-phenacetin analgesics, no evidence of AN was found. There is no evidence that (ab)use of analgesics or NSAIDs other than phenacetin leads to a pathologically or clinically defined renal disease that could be named AN or AAN.

Trends of analgesic nephropathy in two high-endemic regions with different legislation.

Analgesic abuse is related to a specific form of interstitial nephritis, but the exact nature of the causal agent remains controversial and this has resulted in differences in regulation. In Flanders, the free sale of phenacetin was banned, but the consumption of other combined analgesics remained free. In New South Wales, phenacetin was also banned, but 2 yr later the sales of all combined analgesics were also prohibited. This study compared the evolution of end-stage renal disease as a result of analgesic nephropathy (AN) in these two high-endemic regions with different legislation. In both regions, the time trend of the age-specific incidence of end-stage renal disease as a result of AN is similar in the age group 45 to 54 yr. In all age groups combined, the time trend of the percentage of AN among the patients admitted for renal replacement therapy is also similar. This finding does not support the hypothesis that non-phenacetin mixed analgesics play a significant role in the occurrence of AN.