Performance of a research diet history for use in clinical studies involving pregnant women with and without gestational diabetes mellitus in the Illawarra region, New South Wales.

Objective: To assess the validity and reliability of a research diet history for use in clinical studies of gestational diabetes mellitus (GDM) in the Illawarra region, New South Wales.Design: Diet history interviews conducted at the diabetes service for women with GDM and the prenatal clinic for matched normal glucose tolerant women. The glucose tolerant women provided a repeat diet history two weeks later along with a seven-day weighed food record.Subjects: Fourteen women with GDM and 19 normal glucose tolerant women provided a diet history. Seventeen glucose tolerant women provided food records, and 17 glucose tolerant women provided a repeat diet history.Setting: Illawarra area diabetes service and prenatal clinic, Wollongong hospital, NSW.Main outcome measures: Reported energy and macronutrient intakes.Statistical analysis: Differences in under-reporting in GDM and normal glucose tolerant women assessed by Chi square analysis. Reliability and relative validity assessed using paired t-tests and Pearson's product moment correlation. The number and percent of paired diet history-food record values with > 20% discrepancy were examined. Bland-Altman plots were established to view agreement between diet history and food record data and subsequent regression analysis was applied to assess the extent of systematic bias.Results: The data from the first diet history were plausible. There was no difference between energy and macronutrient data (P > 0.05) and there were correlations between measures (P < 0.05) from repeat diet histories and between diet history and food record data. The degree of discrepancy between diet history and food record data pairs was reasonable. There was no evidence of systematic bias between the diet history and sevenday weighed food record for energy and macronutrient intake measurements.Conclusions: In the absence of dietary counselling, the diet history in this setting was reliable and provided valid results relative to seven-day weighed food record data and with reference to cut-off limits for plausible reporting of energy intakes. [ABSTRACT FROM AUTHOR]