The natural history of renal disease in Australian Aborigines. Part 1. Changes in albuminuria and glomerular filtration rate over time

Background The purpose of this study was to describe changes over time in a lbuminuria and glomerular filtration rate (GFR) in a cohort of Australian A borigines from a community with high rates of renal disease and renal failu re. Methods. Participants were 486 adult community members (20+ years at first exam) who were screened for renal disease and related factors on at least t wo occasions (mean 2.7 occasions), at least a year apart, between 1990 and 1997. Renal function was assessed by the albumin:creatinine ratio (ACR; g/m ol) on a random urine specimen and by the GFR estimated from the Cockcroft- Gault formula. Evolution over time was expressed as the average annual chan ges in these parameters. Results. On baseline examination, 70% of participants had albuminuria (ACR 1.1+ g/mol) There was a significant net increase in ACR and a fall in GFR i n the cohort over time. Among individuals, however, changes were strongly c orrelated with ACR levels at baseline. There was no loss of GFR in persons with normal renal parameters at baseline and a rapid loss of GFR in those w ith substantial levels of albuminuria at baseline. Other factors significan tly correlated with progression of ACR included age, baseline body mass ind ex and systolic blood pressure, the presence of diabetes (or levels of fast ing glucose), and elevated levels of serum gamma glutamyl transferase. Fact ors significantly associated with loss of GFR included body mass index, dia betes, systolic and diastolic blood pressures, microscopic hematuria. and m arginally high cholesterol levels. Conclusion. Albuminuria progresses and GFR is lost over time in individuals in this community, at rates that are strongly dependent on levels of pre-e xisting albuminuria. Much loss of GFR and all renal failure should be avoid ed by preventing the development of albuminuria and minimizing its progress ion. This depends on improving the weight, blood pressure, metabolic profil e of the entire community and reducing infections. Modification of the cour se in people with established disease depends on vigorous control of blood pressure and the metabolic profile and the specific use of angiotensin-conv erting enzyme inhibitors.