Bronchiectasis is a lung disease characterized by the dilation of the lung airways called bronchi. These enlarged bronchi promote mucus accumulation and inflammation, causing recurrent infections and leading to lung failure. Although bronchiectasis is thought to affect 139 in 100,000 American adults, the disease is a concern for health systems due to its associated mortality and serious complications.
Researchers believe that the cause of bronchiectasis is related to host immune defense, environmental factors, and microorganisms that infect the airways. Some diseases such as cystic fibrosis and asthma are frequently associated with bronchiectasis.
Vitamin D is a key molecule known to be involved in inflammation and immune responses. Therefore, a team of Italian researchers sought to investigate whether vitamin D deficiency could be a factor in the clinical severity of bronchiectasis.
To test their hypothesis, the researchers evaluated 57 patients — 17 males and 40 females, with a mean age of 60 years — followed at an outpatient clinic from October 2017 until March 2018.
They measured blood levels of vitamin D (specifically in the form of 25-hydroxyvitamin D, s25OHD), and assessed disease severity with the Bronchiectasis Severity Index (BSI), and a high-resolution computed tomography assessment using the Bhalla score.
The cut-off vitamin D value used was the one established by the Endocrine Society guidelines. Vitamin D was considered deficient when levels were lower than 20 nanograms per milliliter (ng/mL), and “sufficient” when equal or higher than 20 ng/mL.
For all patients, the mean BSI was 7.5 and Bhalla mean value was 16 (of a maximum of 25 points). Patients considered to be vitamin D deficient had a mean vitamin D level of 17.3 ng/mL, and these patients comprised 64% of the study population. Only 7% of patients had normal levels of vitamin D, with values above 30 ng/mL.
The researchers found that lower levels of vitamin D corresponded with higher BSI and Bhalla scores. No other inflammatory markers showed such a strong association.
Patients with deficient vitamin D levels were also found to experience more frequent episodes of worsening acute respiratory symptoms (respiratory exacerbations), and worse respiratory function, as determined by lower mean forced expiratory volume in one second (FEV1).
“To the best of our knowledge, this is the first study to report a relationship between vitamin D deficiency and clinical and radiological scores in patients with bronchiectasis,” the researchers wrote.
The results suggest that the levels of vitamin D are a potential new reliable marker for bronchiectasis severity.
“We consider vitamin D could be a good predictor of clinical and radiological severity of bronchiectasis, more than other inflammatory markers,” the team concluded.