BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) significantly impacts morbidity and mortality globally. While established risk factors like smoking and occupational exposures are well-documented, patients' beliefs-especially those from the miasma theory attributing disease to "bad air" in cultures like China-may also significantly influence health outcomes. METHODS: This case-control study was conducted at Hospital of Hebei University of Traditional Chinese, involving 500 individuals diagnosed with COPD and 500 matched control participants. Each participant completed questionnaires that gathered information on demographic details, clinical history, and beliefs about the causes of COPD. Clinical data were collected, including spirometry tests to assess lung function, the COPD Assessment Test (CAT) to evaluate symptom burden, and the St. George's Respiratory Questionnaire (SGRQ) to measure health-related quality of life. RESULTS: The study found that 81% of COPD patients endorsed high miasma beliefs, compared to 28% of controls (p <
0.01). Those with strong beliefs reported significantly worse symptoms (mean CAT score: 23 vs 14, p <
0.001) and poorer quality of life (mean SGRQ score: 48 vs 39, p <
0.001) compared to low-belief individuals. Higher levels of anxiety and depression were also observed in patients with strong miasma beliefs. Laboratory biomarkers such as neutrophils, RDW width, and CRP were also elevated in the high-belief group compared to the low-belief group. CONCLUSION: The findings suggest that adherence to miasma theory beliefs is associated with adverse health outcomes in COPD patients. Addressing these beliefs through targeted education may enhance patient engagement and adherence to evidence-based treatments, ultimately improving health outcomes.