Patterns of dietary intake and serum lipids interact with proteinuria as risk factors for progression of chronic renal failure

This prospective study assessed the interactions between patterns of nutrient intake and serum lipids with other risk factors for progression of chronic renal failure. The study cohort consisted of 52 individuals with documented chronic renal failure, 18 women and 34 men, with a mean age of 65 ± 11 years at the time of recruitment. The dependent variable was the rate of progression of chronic renal failure, which was determined by the slope of the curve generated from five or more values of the reciprocal of serum creatinine (S(Cr^-1)) and divided by time (m months of follow-up) for each patient, and recorded in dung/month. The independent variables included dietary factors (phosphorus, protein); serum lipids (total cholesterol, LDL- cholesterol, HDL-cholesterol, triglycerides); proteinuria; serum phosphorus; serum albumin; serum glucose; and blood pressure. Serum creatinine was drawn in a fasting state and determined using the picric acid technique on five or more occasions for each patient. The mean monthly rate of decline in dL/mg/month was calculated for each patient. The cohort was followed for 1.5 years. Descriptive statistics were determined for all variables. Analysis of principal components was used to generate variables representing patterns of nutrient intake and serum lipids. The outcome variable was modeled using stepwise linear regression which included principal components representing dietary and serum lipid patterns. The Student's t test and the F test were used for hypothesis testing. All tests were significant at p < 0.05. Results and Conclusions: Multicolinearity prevented the inclusion of more than one individual dietary or serum lipid variable into the multiple linear regression model of rate of decline in kidney function. Principal components representing patterns of dietary intake and serum lipids, contributed to the prediction of rate of decline in renal function together with proteinuria.