Vitamin D deficiency and its potential associations on the health status of older patients with chronic obstructive pulmonary disease in rural Crete, Greece: A cross-sectional study

While low vitamin D levels are common in Chronic Obstructive Pulmonary Disease (COPD) and have been associated with various adverse COPD-related outcomes, data on vitamin D status in rural COPD cohorts is limited. Therefore, the present study aimed to assess the prevalence of Vitamin D deficiency among patients with COPD living in rural areas and explore its potential association on the overall health status. This cross-sectional study included 138 participants >40 years with COPD from the prospective "COlaborative care vs usual CARE in primary care patients with COPD" (COCARE) study. Sociodemographic characteristics, medical history, patient's health-related quality of life (HRQoL) with the COPD Assessment Test (CAT), fatigue with the Fatigue Severity Scale (FSS), phycological parameters with Patient Health Questionnaire-9 (PHQ-9) and General Anxiety Disorder-7 (GAD-7), sleep disorders with the COPD and Asthma Sleep Impact Scale (CASIS), Athens Insomnia Scale (AIS) and the Epworth Sleepiness Scale (ESS) were collected. Vitamin D deficiency was defined as levels of 25-hydroxy (OH)-Vitamin D below 20 ng/mL. Multiple logistic regression analysis was conducted to test for associations of Vitamin D deficiency with CAT, FSS, PHQ-9, GAD-7, CASIS, AIS, and ESS, adjusting for age, gender, smoking status, comorbidities, and seasonality. Most of the participants were male (70%) with a mean age of 68 ± 9 years and a mean Body Mass Index (BMI) of 30 ± 6 kg/m2. Moreover, 33% of the participants had Vitamin D deficiency. Vitamin D deficiency increased the odds for worse HRQoL (CAT≥10 OR: 2.3, CI: 0.9 - 6.4, p=0.008), greater fatigue severity (FSS, OR: 1.2, CI: 0.4 - 3.1, p=0.756), more depressive (PHQ-9≥5, OR: 2.9, CI: 1.1 - 7.4, p=0.024), anxiety (GAD-7, OR: 0.8, CI: 0.3 - 2.1, p=0.592) and insomnia symptoms (AIS score OR: 1.1, CI: 0.7 - 5, p=0.29), excessive daytime sleepiness (ESS, OR: 1.1, CI: 0.7 - 5, p=0.29), and lower sleep quality (CASIS OR: 2.5, CI: 0.9 - 6.5, p=0.006). In conclusion, our findings indicate that Vitamin D deficiency is positively associated with numerous negative health outcomes of patients with COPD, including worse HRQoL, fatigue, depression, anxiety and sleep disorders. However, further research is needed to determine the role of Vitamin D in the health status of these patients.