IL6 and overlapping connective tissue disease: Individuals with OSA or overlap syndrome (OS), defined as the coexistence of chronic obstructive pulmonary disease (COPD) and sleep apnea, exhibit higher levels of inflammatory markers, such as hs-CRP, interleukin-6 (IL-6), and granulocyte colony-stimulating factor (G-CSF), compared to those with OSA alone.