Muco-active Agent Use and Clinical Outcomes After Lung Cancer Diagnosis in Chronic Obstructive Pulmonary Disease

The Target Trial Emulation of Muco-active Agent Use and Clinical Outcomes After Lung Cancer Diagnosis Among Patients With Chronic Obstructive Pulmonary Disease (TAME-CLC) study is a retrospective observational cohort study using existing real-world data from the Korean Cancer Data Center (K-CURE) database to evaluate whether use of muco-active agents is associated with clinical outcomes after lung cancer diagnosis among adults with chronic obstructive pulmonary disease (COPD) and localized-stage lung cancer. The investigators will not assign any treatment or medication. Instead, the study will emulate a hypothetical target trial using routinely collected retrospective data. Eligible patients will be adults aged 40 to less than 80 years who have COPD before lung cancer diagnosis and meet prespecified diagnostic and treatment-based criteria. Patients will be classified according to muco-active agent treatment strategies based on prescription records after the first lung cancer diagnosis. The emulated treatment strategy is use of any muco-active agent within a prespecified grace period after lung cancer diagnosis. The comparator strategy is no muco-active agent use during the same grace period. Muco-active agents include mucolytics, mucoregulators, expectorants, and mucokinetics, such as N-acetylcysteine, erdosteine, carbocysteine, guaifenesin, ivy-leaf extract, ambroxol, and bromhexine. The primary outcome is time to moderate-to-severe COPD exacerbation after lung cancer diagnosis. Secondary outcomes include all-cause mortality, cancer-related mortality, and respiratory disease-related mortality. A clone-censoring-weighting approach will be used within a target trial emulation framework to estimate the modified intention-to-treat effect of muco-active agent use while adjusting for measured baseline differences between treatment strategies.