Analgesic nephropathy in Canada: a retrospective study of 351 cases.

Data concerning 351 patients with analgesic nephropathy was obtained by a survey of Canadian nephrologists and suggested an incidence of at least 20, and of perhaps 50 cases per million population. Renal function at the time of diagnosis (as judged by serum creatinine level) was normal in 15%, mildly to moderately impaired in 59%, and severely impaired in 26% of cases. Follow-up serum creatinine level in 222 cases showed that renal function became worse in 42% of cases, with terminal renal failure developing in one-half of these patients. However, significant improvement in kidney function was observed in 25% of patients. Cessation of analgesic abuse considerably increased the likelihood of improvement in renal function.