Dietary Management of Phosphorus in Hemodialysis: Content Analysis of Clinical Nutrition Textbooks

Abstract

The purpose of this work was to conduct content analysis of college-level clinical nutrition textbooks, specifically text coverage of dietary management of phosphorus for individuals with chronic renal disease undergoing hemodialysis treatment. Seven clinical nutrition textbooks were identified in Books-in-Print electronic database (Bowker LLC) using title keywords, namely “clinical” AND “nutrition,” and publication dates 2011 to 2014. The evidence base for phosphorus management was determined from a systematic literature review (Kalantar-Zadeh et al. Clin J Am Soc Nephrol. 2010; 5:519-530) and organized into discrete content categories. Two researchers independently reviewed the clinical nutrition textbooks relative to the content categories of the evidence base. Content categories (i.e., outcome measures) included phosphorus from animal sources, phosphorus from plant sources, phosphorus from food additives, and phosphorus-to-protein ratio. Restricting phosphorus intake was mentioned in general in all seven clinical nutrition textbooks. Managing phosphorus, however, from animal sources was mentioned in only three textbooks; managing phosphorus from plant sources was also mentioned in these three textbooks but with no qualification that phosphorus in grain products is phytate bound. Managing phosphorus derived from food additives was mentioned in only one textbook yet this inorganic phosphorus is more bioavailable than organic phosphorus from animal sources as well as increasingly prevalent in the food supply. Phosphorus-to-protein ratio (mg/g) was not mentioned. Content analysis of clinical nutrition textbooks suggested that the majority of textbooks do not address the complexity of phosphorus management, particularly with respect to food additive sources, which may inhibit optimal evidence-based education and subsequent clinical practice.