Abstract: Objectives: To analyze the correlation between serum vitamin D and severity of community-acquired pneumonia (CAP) in elderly people. Methods: A total of 235 cases of elderly people with CAP were enrolled and were divided into severe CAP group(39 cases) and common CAP group (196 cases). And 219 healthy elderly people were served as controls.Levels of serum 25-(OH)D₃, procalcitonin( PCT), hsCRP, serum C-reactive protein (CRP) and electrolytes were determined, and blood routine and arterial blood gas were detected. The diagnostic value of serum 25-(OH)D₃ level for CAP was evaluated by ROC curve. Results: The levels of serum 25-(OH)D₃, PCT, hsCRP, CRP, WBC count, PMN%, PaO₂, calcium between the three groups were statistically different (F=117.66, 21.79, 53.21, 113.86, 91.83, 179.83, 30.46, 22.34, P<0.05). Pearson correlation analysis showed that serum 25-(OH)D₃ level was negatively correlated with hsCRP, CRP, WBC (r=-0.81, -0.23, -0.18, P<0.05), and positively correlated with PaO2, calcium (r=0.22, 0.27, P<0.05). The multi-variable logistic regression analysis showed that serum low level of 25-(OH)D₃ was highly correlated with the severity of CAP. The ROC curve analysis showed that serum 25-(OH)D₃ had good diagnostic value for severe CAP (area under the curve was 0.864, 95% CI was 0.83~0.90, P<0.05). Conclusions: Serum vitamin D deficiency is closely correlated with severity of CAP in elderly people and is a high risk factor for severe CAP. Early detection of serum vitamin D level has clinical significance in evaluating the severity of CAP to some extent.

Key words: Community-acquired pneumonia, Vitamin D, Risk factor, Severe pneumonia, Elderly people