Association Between Serum Vitamin D Level and Uncontrolled Chronic Rhinosinusitis With Nasal Polyposis

<b>Objective:</b> Chronic rhinosinusitis with nasal polyposis (CRSwNP) is characterized by type 2 inflammation, and studies have shown that conventional therapy usually yields unsatisfactory results. While recent studies have indicated the potential effect of vitamin D on allergic and inflammatory diseases, including CRSwNP. Therefore, this study aimed to investigate the relationship between serum vitamin D levels and the severity of CRSwNP using endoscopic evaluations, imaging, patient-reported outcome measures, absolute eosinophilic count, and serum vitamin D levels and determine the prevalence of vitamin D deficiency in patients with CRSwNP. <b>Methods:</b> Serum vitamin D levels were measured in 104 patients with uncontrolled CRSwNP, who failed maximum medical management and were scheduled for functional endoscopic sinus surgery. Vitamin D levels were compared between patients using the Lund- Mackay (LM) score, Sinonasal Outcome Test-22 (SNOT-22), total nasal polyp scores, and absolute eosinophil counts. <b>Results:</b> The 104 included patients had an average age of 42.09 ± 13.3 years, and 63.5% of them were male. Mean value of vitamin D was 57.9 ± 31.2 nmol/L. The average SNOT-22 score was 65.49 ± 21.3. The mean LM score was 14.48 ± 6.64. The total nasal polyp score was 4.3 ± 2.08. Vitamin D levels were negatively correlated with LM score (<i>r</i> = -.210, <i>P</i> = .032) and polyp grade (<i>r</i> = -.264, <i>P</i> = .007), but did not correlate with other variables. <b>Conclusions:</b> Our study indicates that vitamin D deficiency or insufficiency is common in patients with CRSwNP. We found that low serum vitamin D levels were negatively correlated with the Lund-Mackay score and the total nasal polyp score, providing additional support for an association between low vitamin D levels and a greater severity of CRSwNP.