Increasing Vitamin D Serum Levels Is Associated With Reduced Pulmonary Exacerbations in Patients With Cystic Fibrosis.

CONTEXT

In 2012, The North American Cystic Fibrosis Foundation (NACFF) published new guidelines for the treatment of vitamin D deficiency in individuals with cystic fibrosis (CF).

OBJECTIVE

The objectives of our study were to assess the efficacy of these guidelines, and to test the effect of increasing vitamin D dosage on pulmonary function and exacerbations.

DESIGN

Pulmonary function tests and serum concentrations of 25-hydroxyvitamin D [25(OH)D] were measured 1 year before increasing vitamin D dosage according to the guidelines and at least 1 year later. In addition, days of hospitalization and pulmonary exacerbations were counted and an average per year (average number of days of hospitalization and average number of pulmonary exacerbations [PEA], respectively) was calculated.

SETTING AND PARTICIPANTS

A total of 90 patients from The Cystic Fibrosis Clinic at Hadassah Mount-Scopus Hospital, Jerusalem, Israel.

RESULTS

The mean serum concentration of vitamin D increased significantly from 20.97 ng/mL (52.34 nmol/L) at baseline to 25.41 ng/mL (63.42 nmol/L) at the end of follow-up (P < 0.001). The number of PEA decreased significantly from 2.79 ± 3.96 to 2.15 ± 2.91 (P = 0.007). The change in vitamin D levels was correlated with a decrease in PEA (correlation coefficient = -0.318, P = 0.002).

CONCLUSIONS

The NACFF guidelines for management of vitamin D deficiency improve vitamin D levels in patients with CF but did not reach the normal values in most patients. The increase in vitamin D serum levels was, however, associated with a decrease in number of pulmonary exacerbations.