REGRESSION EQUATION PREDICTS DIETARY PHOSPHORUS INTAKE FROM ESTIMATE OF DIETARY-PROTEIN INTAKE

Objective To develop a predictive equation for dietary phosphorus inta ke. Design In this clinic-based, cross-sectional study, a dietitian-ad ministered food frequency questionnaire provided dietary intake estima tes for a population of patients with chronic renal failure. A predict ion equation for dietary phosphorus intake was developed and was valid ated on another sample of patients with CRF from the same clinic. Subj ects Outpatients treated for chronic renal failure at the E. Wolfson M edical Center Institute of Nephrology in Holon, Israel, participated i n the study (N=104, 73 men and 31 women, mean age=65.6 years). The val idation sample consisted of 53 outpatients with chronic renal failure (38 men and 15 women, mean age=64.2 years) from the same clinic. Main outcome measures Dietary variables (ie, energy, protein, carbohydrate, fat, phosphorus) were examined in terms of crude intake, as percentag e of total energy intake, and per kilogram of body weight. Statistical analyses performed Stepwise linear regression analysis and Student's t tests were used to examine relationships between dietary phosphorus and other variables. Results Dietary phosphorus (milligrams)=128+14 (p rotein intake [grams]) was the best-fitting equation and explained 84% of the variance in dietary phosphorus intake. Applications The predic tion equation for dietary phosphorus intake is especially useful for r enal dietitians who calculate patient diets by hand.