Vitamin D deficiency is associated with a higher risk of incident nontuberculous mycobacteria (NTM) respiratory isolation in adults with cystic fibrosis (CF), according to retrospective study results published in the Annals of the American Thoracic Society.

Structural lung disease likely contributes to elevated NTM risk in patients with CF; therefore, identification of modifiable risk factors may help to reduce infections. Individuals with CF are at high risk for vitamin D deficiency because of pancreatic exocrine insufficiency. Therefore, researchers investigated whether vitamin D deficiency was a risk factor for incident NTM respiratory isolation in a cohort of 254 adults with CF cared for by the Johns Hopkins CF Center between January 1, 2007, and December 31, 2018.

During the 12-year study period, 50 individuals (19.7%) had a positive NTM culture, with Mycobacterium avium as the most commonly identified NTM species (58%). Individuals who acquired NTM had a significantly higher forced expiratory volume in 1 second (FEV1), lower rates of macrolide use, and Pseudomonas aeruginosa infection at time of study entry, but baseline vitamin D levels did not differ significantly. Vitamin D deficiency was more common (35.1% vs 22.1%; P <.01) and mean vitamin D values were lower (25.7 ng/mL vs 29.1 ng/mL; P =.03) among vitamin D measurements prior to positive NTM cultures compared with those prior to negative NTM cultures. Persistent vitamin D deficiency was more frequently observed in individuals who became NTM positive (28.0%) than those who remained NTM negative (15.7%).

“The potential increased risk of NTM conferred by [vitamin D deficiency] may have important clinical consequence for the management of individuals with CF,” the study authors wrote. “More frequent monitoring of vitamin D levels and targeted attempts at aggressive repletion — especially in those that are significantly deficient — and may warrant investigation as to whether this would reduce risk of NTM infection.”


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Reference

Richter WJ, Sun Y, Psoter KJ, et al. Vitamin D deficiency is associated with increased nontuberculous mycobacteria risk in cystic fibrosis. Ann Am Thorac Soc. Published online November 16, 2020. doi:10.1513/annalsats.202003-216rl