Factors Associated with Vitamin D Levels in Patients with Chronic Obstructive Pulmonary Disease in Combination with Renal Dysfunction

The goal of the study was to analyze factors associated with vitamin D levels in patients diagnosed with chronic obstructive pulmonary disease (COPD) in combination with the early stages of renal dysfunction. The study covered 338 patients with first- and second-degree COPD (including 66.9% men with a mean age of 69.4 ± 6.1 years and an average COPD duration of 18.5 ± 4.1 years and 33.1% women with a mean age of 64.8 ± 7.3 years and an average COPD duration of 12.1 ± 5.1 years). All patients were diagnosed with first- and second-degree chronic kidney disease (CKD). In addition to general clinical examinations, potential risk factors for vitamin D deficiency were assessed in all patients. In multiple regression with step-by-step inclusion of signs, the following identified factors made a significant contribution to the levels of vitamin D synthesis in patients with COPD in combination with the early stages of renal dysfunction: annualized relapse rate of COPD (3 (2–4), β = –0.932, p = 0.003), smoking index (SI) (44 (15–87), β = –0.038, p = 0.006), fibrinogen level (5 (3–7), β = –0.413, p = 0.016), GFR (74.9 (68.4–89), β = –0.119, p = 0.041), insolation (94.5 (38.5–152), β = 0.026, p = 0.0008), the total score on the GDS scale (9 (8–11), β = –0.536, p = 0.014). R² for this model was 0.87. BMI made a significant contribution to the level of vitamin D synthesis at the stage of inclusion in multivariate analysis, but the connection weakened and completely disappeared with the inclusion of smoking index values when insolation indicators were added to the analysis. FEV1 values do not affect the vitamin D level in COPD patients in combination with early stages of kidney dysfunction.