Kinder and his colleagues assessed the prevalence of vitamin D deficiency in a cohort of patients with interstitial lung disease, who are often treated with corticosteroids. The detrimental effect of chronic use of corticosteroids on bone health has been well established, according to the researchers. Of the patients included in the study, 51 had interstitial lung disease and 67 had other forms of interstitial lung disease related to autoimmune connective tissue diseases.
A vitamin D insufficiency was defined as a serum level of less than 30 ng/mL. A level of less than 20 ng/mL was considered deficient. Both insufficient and deficient levels were prevalent in the study. In the overall sample, lower vitamin D levels were associated with reduced forced vital capacity (P=0.01). When the analysis was restricted to patients with connective tissue disease, both forced vital capacity and diffusing capacity of lung for carbon monoxide — a measure of the lung’s ability to transfer gases from the air to the blood — were significantly reduced (P<0.05 for both). After adjustment for several potential confounders — including age, corticosteroid use, race, and season, the presence of connective lung disease was a strong predictor of vitamin D insufficiency (OR 11.8, 95% CI 3.5 to 40.6).
According to the researchers, a pathogenic role of low vitamin D in the development of autoimmune diseases such as interstitial lung disease is plausible because of the immunoregulatory role of the biologically active form of vitamin D, 1,25-(OH)2D. “All cells of the adaptive immune system express vitamin D receptors and are sensitive to the action of 1,25-(OH)2D,” they wrote. “High levels of 1,25-(OH)2D are potent inhibitors of dendritic cell maturation with lower expression of major histocompatibility complex class II molecules, down-regulation of costimulatory molecules, and lower production of proinflammatory cytokines.” “A common theme in the immunomodulatory functions of vitamin D is that higher levels are immunosuppressive,” they continued, “which is consistent with a potential role for hypovitaminosis D in the pathogenesis of autoimmune disorders.”
In a statement, Len Horovitz, MD, a pulmonary specialist at Lenox Hill Hospital in New York City, commented that “vitamin D is known to promote wound healing, and to benefit the immune system. So it is not surprising to find that patients with immune lung disorders are vitamin D deficient.” He said that all of his patients are screened and treated for vitamin D deficiency with supplements. The study authors noted that further research is needed to determine whether supplementation is associated with improved outcomes. The study was limited, Kinder and his colleagues wrote, by its use of patients from a single center in Cincinnati.
In addition, the cross-sectional design of the study did not evaluate whether vitamin D supplementation is associated with any improved clinical outcomes. To examine that issue, the team called for prospective controlled interventional studies to determine whether vitamin D7 supplements can ameliorate symptoms and improve outcomes in connective tissue disease-related interstitial lung disease.
Source reference: Hagaman J, et al “Vitamin D deficiency and reduced lung function in connective tissue-associated interstitial lung diseases” Chest 2011; DOI: 10.1378/chest.10-0968.
Asthma and chronic obstructive pulmonary disease (COPD) patients who are treated with inhaled corticosteroids may face a significantly higher relative risk for both the development and progression of diabetes, new Canadian research suggests. The warning stems from an analysis of data involving more than 380,000 respiratory patients in Quebec. Inhaler use was associated with a 34 percent increase in the rate of new diabetes diagnoses and diabetes progression, the researchers found. What's more, asthma and COPD patients treated with the highest dose inhalers appear to face even higher diabetes-related risks: a 64 percent jump in the onset of diabetes and a 54 percent rise in diabetes progression. “High doses of inhaled corticosteroids commonly used in patients with COPD are associated with an increase in the risk of requiring treatment for diabetes and of having to intensify therapy to include insulin,” the study team noted in a news release.
Based on their results, researchers from McGill University and the Lady Davis Research Institute at Jewish General Hospital in Montreal suggest “patients instituting therapy with high doses of inhaled corticosteroids should be assessed for possible hyperglycemia and treatment with high doses of inhaled corticosteroids limited to situations where the benefit is clear.”
Lead investigator Samy Suissa colleagues report their findings in the most recent issue of the American Journal of Preventive Medicine.
The research team wrote that despite the fact that inhalers are recommended for use solely by the most severely ill COPD patients, they are typically prescribed for a much broader pool that amounts to about 70 percent of all COPD patients. The authors found that more than 30,000 of the COPD/asthma patients in their study developed a new diagnosis diabetes over the course of five and a half years of treatment. This amounted to a diabetes onset rate of a little more than 14.2 out of every 1,000 inhaler patients per year.
“These are not insubstantial numbers,” Suissa said. “Over a large population,m the absolute numbers of affected people are significant.” In addition, in the same timeframe nearly 2,100 patients already diagnosed with diabetes before using inhalers experienced a worsening of their disease that ultimately required upgrading their diabetes care from pills to insulin shots.
Dr. Stuart Weiss, an endocrinologist with the New York University Medical Center, suggested that concern should be directed more at the underlying causes of both diabetes and asthma/COPD rather than at inhalers themselves. “I would say that a lot more attention should first be paid to the lifestyle choices, dietary-wise, that lead to the pro-inflammatory conditions that raise the risk for both type 2 diabetes as well as COPD and asthma,” said Weiss, who is also a clinical assistant professor at the NYU School of Medicine in New York City. “We don't look at asthma as being a dietary condition, but it absolutely is. Which means that in terms of diabetes and asthma risk, the body is reacting to similar stresses brought about by the over-consumption of overprocessed foods and the lack of consumption of green vegetables.”
Noting that the underlying risk for both conditions is similar, Weiss said he suspected the steroids themselves should not bear all the blame. “What may be more at the root of this problem,” he said, “is the fact that those who are most at risk for diabetes are the same people who have the worst asthma and COPD that requires steroid treatment in the first place.” “Yes, we do know that steroids increase insulin resistance and that people treated with steroids require more aggressive diabetes management,” he conceded. “But if we don't generally take an approach that deals with the poor quality of food that people are routinely consuming, the incidence of both these diseases will continue to go up at a dramatic rate.”