Assessing vitamin D levels in patients with asthma and polymorbidity

BACKGROUND: Despite numerous research into the role of vitamin D deficiency in various disorders, its impact on the clinical course and control of asthma in patients with systemic inflammation-associated polymorbidity is insufficiently studied.

AIM: This study aimed to assess the relationship between vitamin D levels, pro-inflammatory cytokine levels, oxidative stress, and asthma control in patients with asthma, obesity, and polymorbidity.

METHODS: A one-time (cross-sectional) cohort study was conducted. Patients with asthma were divided into three groups: with normal body weight, increased body weight, and obesity. The levels of vitamin D, interleukin 6, tumor necrosis factor alpha, and leptin, the degree of oxidative damage to biomolecules, the level of asthma control according to the Asthma Control Questionnaire (ACQ-5), and the polymorbidity index were assessed.

RESULTS: The study included 237 patients. Vitamin D insufficiency and deficiency were reported in 57.8% and 35.8% of patients with obesity, respectively. Vitamin D levels declined as the number of comorbidities increased, with the lowest levels reported in patients with five or more concomitant conditions (p < 0.05). Obesity was associated with lower vitamin D levels than normal body weight, regardless of the number of comorbidities (p < 0.05). There was a negative correlation between vitamin D levels and asthma control level according to ACQ-5 (r = −0.3593), body mass index (r = −0.3036), interleukin 6 levels (r = −0.1644), tumor necrosis factor alpha levels (r = −0.2596), degree of oxidative damage to biomolecules (r = −0.2129), and leptin levels (r = −0.2756). Patients with obesity and uncontrolled asthma had the most severe vitamin D deficiency (21.7 [18.8; 24.5] ng/mL). Oxidative stress was two times higher in patients with normal body weight and vitamin D deficiency (p < 0.05). Patients with obesity had significantly higher interleukin 6 and tumor necrosis factor alpha levels, as well as a significantly higher degree of oxidative damage to biomolecules, regardless of vitamin D levels (p < 0.05).

CONCLUSION: Low vitamin D levels in patients with asthma and polymorbidity may be associated with increased pro-inflammatory cytokine levels and poor asthma control. Vitamin D deficiency in patients with asthma, obesity, and polymorbidity is a significant modifiable risk factor in clinical practice. The management of vitamin D deficiency can be a part of comprehensive treatment and rehabilitation in these patients.