Validation of a calcium assessment tool in postmenopausal Canadian women

Abstract

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.