Validation of a short calcium intake list to estimate daily dietary calcium intake of patients with osteoporosis

Background/Purpose: Calcium supplements are prescribed for prevention of osteoporotic fractures, but excess intake has been associated with cardiovascular events. The most adequate tools for estimating dietary calcium intake are timeconsuming, while an accurate estimation is a prerequisite to be able to prescribe the adequate amount of supplementation. The aim of this study is to validate a Short Calcium Intake List (SCaIL) that is feasible in daily clinical practice, with an extensive dietary history (DH) as reference method. Methods: Based on the Dutch food groups which contribute most to daily dietary calcium intake and on portion sizes determined in our earlier validation study, a new three-item, one minute SCaIL was designed. As a reference method, an extensive DH with specific focus on calcium products and extra attention for portion sizes was performed. Beforehand, a difference of >250 mg calcium between both methods was considered clinically relevant. Results: Sixty-six patients with either primary (n=40) or secondary (n=26) osteoporosis were included. The SCaIL showed a very small and clinically non-relevant difference with the DH: mean 24 +/- 350 mg calcium per day (1146 +/- 440 vs 1170 +/- 485, respectively; p=0.568). Sensitivity and specificity of the SCaIL, compared to the DH, were 73% and 80%, respectively. However, in 50% of the individuals, a clinically relevant difference was observed between both methods, while in 17% a difference of >500 mg was observed. Conclusion: The SCaIL is a quick and easy questionnaire to estimate dietary calcium intake at a group level, but is not sufficiently reliable for use in individual patients. Remarkably, mean dietary calcium intake via the DH is 1170 mg per day, which indicates that a large proportion of osteoporosis patients might not even need calcium supplementation.