Ready reckoners are used in the clinical setting as a tool for the estimation of nutrient intake. With increasing opportunities for nutrition research, ready reckoners may provide for a more rapid analysis of nutritional intake than computerised methods, often seen as the gold standard for nutritional analysis. This research aimed to determine the level of agreement between ready reckoner and computerised dietary analysis through a secondary analysis of clinical trial data. Participant food intakes were estimated by trained observers using the one-quarter method. Daily energy and protein intake were estimated by the healthcare network ready reckoner and computerised dietary analysis. Agreement between methods was tested using t-tests, correlations and Bland-Altman plots. A correlation between analysis methods was observed (r = 0.9086 energy, r = 0.8700 protein). Wide limits of agreement were observed for both energy and protein intake. Compared with the computerised method, ready reckoner analysis underestimated energy intake by 600 kJ and protein intake by 5 g. Mean energy and protein intake calculated by each method was significantly different (p < 0.0001 energy; p < 0.0001 protein). No time differences between analysis methods were observed. In the clinical setting, practitioners should be aware of the variability of a ready reckoner compared to computerised dietary analysis. Further investigation into the acceptability of ready reckoners as a reliable method of nutrient intake determination, particularly for analysis of nutrition research, is required.
Keywords: Bland-Altman; computerized dietary analysis; nutritional analysis; ready reckoner.