Adequate calcium intake is important for optimal bone health. Assessing dietary calcium intake, however, is neither widely done nor standardized in North American clinical practices.
Objective: Our goal was to validate a calcium assessment tool (CAT), a modified version of the Calcium Calculator™, against the 3-day food record.
Methods: Data were obtained from 348 participants in the ECKO (Evaluation of the Clinical use of vitamin K supplementation in postmenopausal women with Osteopenia) trial. In this study, CAT data was collected at baseline and 3-day food records (FRs) were collected at baseline and 3 months by trained study coordinators. CAT and 3-day FR data were compared using correlations and Bland-Altman plots. Additionally, receiver operator characteristic (ROC) curves of CAT were constructed to identify subjects with low calcium intake at thresholds of 500 mg/day and 1000 mg/day on the 3-day FR curves.
Results: Mean calcium intake values per day were 902 mg for the 3-day FRs and 781 mg for the CAT. The Pearson correlation was 0.57 (95% CI: 0.50-0.64). Areas under the ROC curves at thresholds of 500 and 1000 mg calcium were 0.81 (95% CI: 0.73-0.89) and 0.82 (95% CI: 0.78-0.86), respectively.
Conclusions: The CAT is a valid tool for the measurement of dietary calcium intake using cut-off values of 500 mg and 1000 mg in postmenopausal women, even though there is only moderate correlation between the CAT and 3-day FR. This tool may facilitate the determination of whether calcium supplements are needed in the clinical setting.
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