Retrospective real world study on vitamin D supplementation: Looking for the most effective molecule and its frequency of use.

BACKGROUND & AIMS: There is still uncertainty regarding the optimal serum levels 25-Hydroxy-vitamin D [25(OH)D] and the most effective supplementation strategies, including the choice of molecule and its dosing frequency. The aim of the study is to compare the effects of calcifediol versus two different frequencies of cholecalciferol administration on vitamin D supplementation, and to identity the key parameters that predict response to treatment.

METHODS

This retrospective, real-world cohort study included 105 patients, who were divided into three groups. Group 1 (n = 21) received cholecalciferol 50,000 international units (UI) once a month, Group 2 (n = 27) received cholecalciferol 25,000 UI every two weeks, and Group 3 (n = 57) received calcifediol 0.266 mg (mg) once a month. The primary outcome measured was the delta increase in 25(OH)D levels after 6 months of treatment, compared to pre-treatment levels.

RESULTS

The study revealed a significant greater delta increase in 25(OH)D levels in Group 1, which received cholecalciferol 50,000 IU once a month, compared to the other two groups. However, multiple regression analysis indicated that neither the type of molecule nor the frequency of administration independently influenced the treatment outcome. Only pre-treatment serum 25(OH)D levels were found to significantly affect the outcome. Based on the receiver operating characteristic curve, serum 25(OH)D levels below 19.5 ng/dL were predictive of a doubling of pre-treatment values, with high sensitivity and specificity.

CONCLUSION

Pre-treatment serum 25(OH)D levels are valuable for selecting patients who should undergo supplementation. This finding suggests the importance of tailoring therapy according to the degree of vitamin D deficiency.