Aims Patients with cystic fibrosis (CF) require supplementation of fat-soluble vitamins due to the effects of the disease on the pancreas and the resulting inability of absorb fat effectively.¹

The study aimed to assess the effectiveness of current of vitamin D supplementation to achieve adequate serum Vitamin D (25OHD) levels in paediatric CF patients.² Secondly, this study assessed the effectiveness of ‘Stoss’ therapy (a high dose vitamin D therapy administered every three months) as an alternative to daily vitamin D supplementation for patients with known poor compliance.³

Methods Vitamin D doses and serum 25OHD levels between January and December 2016 were reviewed for paediatric CF patients at a UK centre. Data was collected for 138 paediatric patients. The ‘clinical record summary’ system was used to extract the data which included age, hospital number, weight in 2015 and 2016, 25OHD levels from 2015 and 2016, vitamin D dose before each level and pancreatic status.

Data was entered onto Statistical Package for the Social Sciences (SPSS) system for analysis. A paired T-test was conducted to ascertain if there was a significant difference in weekly/kg doses between patients that were sufficient (25OHD>50 nmol/L) and insufficient (25OHD<50 nmol/L).

Results Data was collected for a total of 138 patients. The data from only 70 patients was analysed when investigating the first objective, as all other patients did not have 25OHD levels available for both 2015 and 2016. A further five patients wereexcluded and analysed seperately due to receiving Stoss therapy. The weekly Vitamin D dose range was very wide for both years with 43% (n=40) of patients requiring additional vitamin D in addition to Aquadeks (CF multivitamin preparation). There was no significant difference in Vitamin D doses between patients with sufficient and insufficient 25OHD levels. This was thecase for both 2015 (p=0.432) and 2016 (p=0.192). The daily supplementation doses were successful at maintaining vitamin D sufficiency for 83% of patients in 2015 and 93% in 2016.

Out of the 5 patients who received ‘Stoss’ therapy, 3 had an increase in 25OHD levels. However, only one of the patients had a significant increase leading to sufficient 25OHD levels. In 2 cases there was actually a 60%–68% decrease in 25OHD levels, which lead to these patients developing vitamin D deficiency.

Conclusion This study was useful in determining the effectiveness of current Vitamin D dosing. The results suggest that patients having insufficient 25OHD levels may not be due to an inadequacy of doses provided in the current guideline, as there was no significant difference in dose between patients with sufficient and insufficient 25OHD levels. Given the patient group, the difference could be attributable to a lack of compliance to daily therapies in the patients with insufficient 25OHD levels or even differences in individual responses to therapy.

In this sample, ‘Stoss’ therapy is not effective in maintaining sufficient 25OHD levels. Although the data for this part of the study was very limited, it identifies a need to investigate the effectiveness of ‘Stoss’ therapy further.

References

1. Ferguson JH, Chang AB. Vitamin D supplementation for cystic fibrosis. Cochrane Database of Syst Rev [Internet] 2014. http://onlinelibrary.wiley.com/ & doi:10.1002/14651858.CD007298.pub3/pdf [Available: 2017April 12].

2. Green D, Carson K, Leonard A, et al. Current treatment recommendations for correcting vitamin D deficiency in paediatric patients with cystic fibrosis is inadequate. J Pediatr2008;4:554–559.

3. Shepherd D, Belessis Y, Katz, et al. Single high-dose oral vitamin D3 (stoss) therapy: A solution to vitamin D deficiency in children with cystic fibrosis?J Cyst Fibros2013;2:177–182.