Study design (if review, criteria of inclusion for studies)
non-blinded randomized controlled trial
Participants
patients with CF, pancreatic insufficiency, age 6-21 years with a 25(OH)D <30 ng/mL.
Interventions
trial comparing 50,000 IU of D2 twice weekly for 8 weeks versus 50,000 IU of D3 weekly. All study subjects also received calcium carbonate 500 mg twice daily for 8 weeks.
Outcome measures
The primary outcome was change in serum 25(OH)D level, compared between trial arms by t-test. In addition, the percentage of subjects who achieved normal 25(OH)D levels (>30 ng/mL) were compared between the two trial arms. For secondary analyses, changes in IgG, IgE and CRP in the patients who normalized their vitamin D levels.
Main results
50 patients were enrolled and 47 completed both visits while 3 were lost to follow-up. The mean pre-treatment 25(OH)D level was 23.1 (SD 4.7) ng/mL. The overall mean increase in 25(OH)D level was 11.1 (11.9) ng/mL and 31/47 (66%) achieved a 25(OH)D level>30ng/mL. 26 patients received D2 and the mean change in 25(OH)D was 11.8 (13.8) ng/mL and 18/26 (69%) achieved sufficiency. 21 patients were treated with D3 and the mean change was 10.2 (9.1) ng/mL and 13/21 (62%) achieved sufficiency. Changes in 25(OH)D for both D2 and D3 treatment groups were significant (p<0.001 for both). There is no significant difference in change of 25(OH)D level between the two groups (p=0.65). Similarly, there is no difference in the number of patients to achieve vitamin D sufficiency between treatments (p=0.6). Conditional power calculations indicated that completing the planned 60 patients would provide low probability of demonstrating any statistically significant difference between D2 and D3 with respect to either change in 25(OH)D or achievement of sufficiency. We therefore closed enrollment at 50 patients.
Authors' conclusions
Ergocalciferol 50,000 IU twice weekly for 8 weeks is as effective as 50,000 IU weekly for 8 weeks of cholecalciferol in pediatric patients with CF and vitamin D insufficiency. Overall, only 66% of the patients achieved a 25(OH)D level >30 ng/mL.