Uraemia progression in XXXX stages 3-5 is not constant.

@entity1 @entity8 @entity2316 @entity740 @entity8767 @entity454
INTRODUCTION: @entity740 ( @entity740 ) is a progressive disease leading to loss of glomerular filtration rate (/\GFR, measured in ml/min/1.73 m(2)/year). /\GFR is usually assumed to be constant, but the hyperfiltration theory suggests that it accelerates in severe uraemia. A retrospective analysis of estimated GFR (eGFR) calculated from the Modification of Diet in @entity8 equation was performed to evaluate whether /\GFR is constant or accelerating. METHODS: 1,441 @entity1 attending a nephrology clinic over a 21-year period, with an initial eGFR <60 ml/min/1.73 m(2) and an observation period >= 2 years, were included. eGFR was calculated from all creatinine measurements. 420 @entity1 developed @entity454 ( @entity454 ). First- and second-order polynomial regression analysis of eGFR against time was performed for each @entity1 individually. @entity1 had accelerating uraemia progression if the second-order term coefficient was negative. RESULTS: The initial eGFR was 30.8   15.1 ml/min/1.73 m(2). The second-order coefficient was median -0.15 ml/min/1.73 m(2)/year(2) (interquartile range -0.92, +0.34). Significantly more @entity1 had an accelerating loss (62%, p < 0.001). Acceleration was mainly seen when eGFR was <30 ml/min. /\GFR was mean 1.47    4.5 ml/min/1.73 m(2)/year (male 1.67, female 1.22). @entity454 @entity1 lost 5.4    5.4 ml/min/year/1.73 m(2) during the last year before @entity454 . Accelerating loss was seen for all diagnoses except @entity8767 . Diagnoses with higher /\GFR were @entity8 (3.3 ml/min/1.73 m(2)/year), hypertensive @entity8 (2.1 ml/min/1.73 m(2)/year) and @entity2316 (2.6 ml/min/ 1.73 m(2)/year). There was no evidence of improvement in overall uraemia progression during the period of observation. CONCLUSIONS: Uraemia progression in @entity740 stages 3-5 is not linear, but shows an accelerating trend. This suggests that hyperfiltration mechanisms play a role in @entity740 progression. @entity454 cannot thus be predicted from previous /\GFR alone.
