Natural history of chronic renal failure: a reappraisal.

In this retrospective study we have analysed the rate of progression of renal insufficiency, ascertained from the slopes of the plot of inverse serum creatinine against time, of 102 patients with moderate to severe chronic renal failure (CRF). We have applied 'breakpoint' analysis of the slopes to identify changes in the rate of progression and attempted to determine the factors associated with these changes. Seventy-one patients were found to have progressive CRF, while the remaining 31 had stable or improving renal function. Of the parameters studied, using weighted least-squares analysis, proteinuria was the most significant predictor of progression (regression coefficient: -0.1775, P = 0.0075, adjusted r2 = 0.1059). A positive correlation was observed between proteinuria and diastolic blood pressure (DBP) (r = 0.336, P = 0.0054). Once the predictive value of proteinuria was taken into account, there was no difference in the progression rate between diagnostic groups, other than those patients with polycystic kidney disease who had a significantly faster rate of progression (P = 0.0037). In 49 patients, there was at least one change in the rate of progression with time. There was an inverse correlation between change in slope and a change in DBP (r = -0.352, P = 0.003). We conclude that changes in DBP are often associated with the frequent changes in the rate of progression of CRF. However, a causal link could not be established as in a large number of cases the two changes appeared to occur simultaneously in the absence of changes in antihypertensive therapy.