Secular trends in kidney disease: is the decreased incidence of renal replacement therapy due to a decrease in chronic kidney disease incidence?

Aims: Little is known about trends in renal replacement therapy among patients with chronic kidney disease (CKD) or about changes in the incidence of CKD. We studied the incidence of renal replacement therapy within the population of a health maintenance organization (HMO) both among the entire HMO Population and among those with CKD. Methods: We calculated yearly incidence rates of renal replacement therapy for each year from 1998 to 2005. We defined CKD using the National Kidney Foundation definition of 2 estimated glomerular filtration rates below 60 ml/min/1.73 m(2) 90 or more days apail. Poisson regression assessed year-to-year differences. Results: The number of patients with CKD rose consistently from 3.861 in 1998 to 5,242 in 2005. The proportion of patients who had been diagnosed with hypertension rose from 86.7% (starting renal replacement therapy) or 34.5% (with CKD) to 99.1 and 46.9%. The proportion of patients with diabetes changed little throughout the years studied. The mean estimated (glomerular filtration rate among CKD patients rose minimally from 38.4 ml/min/1.73 m(2) in 1998 to 39.9 ml/min/1.73 m(2) in 2005. Age- and sex-adjusted rates of RRT among patients with CKD varied (p = 0.0034). but did not follow a consistent pattern over time. Conclusions: Incidence of renal replacement therapy among patients with CKD changed little between 1998 and 2005, despite an increase in the number of patients diagnosed with CKD. The discrepancy may be due to increased laboratory identification of CKD.