Validation of a Dietary History Questionnaire against a 7-D Weighed Record for Estimating Nutrient Intake among Rural Elderly Malays.

Energy and nutrient intake estimated using a pre-coded dietary history questionnaire (DHQ) was compared with results obtained from a 7-d weighed intake record (WI) in a group of 37 elderly Malays residing in rural areas of Mersing District, Johor, Malaysia to determine the validity of the DHQ. The DHQ consists of a pre-coded dietary history with a qualitative food frequency questionnaire which was developed to obtain information on food intake and usual dietary habits. The 7-d WI requires subjects to weigh each food immediately before eating and to weigh any leftovers. The medians of intake from the two methods were rather similar and varied by less than 30% for every nutrient, except for vitamin C (114%). For most of the nutrients, analysis of group means using the Wilcoxon matched pairs signed rank sum test showed no significant difference between the estimation of intake from the DHQ and from the WI, with the exceptions of vitamin C and niacin. The DHQ significantly overestimated the intake of vitamin C compared to the WI (p<0.05), whilst, the intake of niacin was significantly underestimated (p<0.05). The consistency of ranking as assessed using the Spearman's rank correlation coefficient (r) was satisfactory since there were positive correlations between all of the investigated nutrients estimated using the DHQ with those assessed using the WI, except for niacin. Furthermore, both the DHQ and the WI classified approximately 38 to 62% of the subjects into the same tertile for all nutrients, except vitamin C. Therefore, the DHQ was modified by adding a checklist of foods rich in vitamin C and niacin. In conclusion, the DHQ was fairly valid for obtaining the usual intake of most nutrients, particularly on a group basis. These findings indicate that in an elderly population with a high prevalence of illiteracy, a specially designed DHQ can provide very similar estimations to that obtained from 7-d WI.