Interpreting incidence trends for treated end-stage renal disease: implications for evaluating disease control in Australia

Abstract

<h4>Background</h4>Five sources of change modify trends in incidence of treated end-stage renal disease (ESRD): (i) demography; (ii) disease control, comprising prevention and treatment of progressive kidney disease; (iii) competing risks, which encompass dying from untreated uraemia or non-renal comorbidity; (iv) lead-time bias; and (v) classification bias. Thus, rising crude incidence of treated ESRD may conceal effective disease control when there has been demographic change, lessening competing risks, or the introduction of bias.<h4>Methods</h4>Age-specific incidences of treated ESRD in Australia were calculated from Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry data by indigenous/non-indigenous status (all causes) and by primary renal disease (non-indigenous only) for two successive decades, 1982-1991 and 1992-2001.<h4>Results</h4>We postulate that less competing risks explained much of the increase in treated ESRD in the elderly and Indigenous Australians. The increase in glomerulonephritic ESRD in non-indigenous Australians could be ascribed mainly to immigration from non-European countries. There was no significant change in incidence of treated ESRD in Indigenous or non-indigenous persons aged less than 25 years, in non-indigenous persons aged 25-64 years for ESRD caused by hereditary polycystic disease or hypertension, or in type 1 diabetics aged over 55 years. End-stage renal disease from analgesic nephropathy had declined. The increase in treated ESRD caused by type 2 diabetic nephropathy appeared to be multifactorial. Lead-time/length bias and less competing risks may have concealed a small favourable trend in other primary renal diseases.<h4>Conclusion</h4>Whether recent disease control measures have had an impact on incidence of treated ESRD is not yet certain, but seems more likely than implied by previous reports.