Respiratory Function, Physical Capacity, and Metabolic Syndrome Components in Combustible Cigarettes and Heated Tobacco Products Users: a Five-Year Follow-Up Cohort Study

Abstract

Purpose: Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide and is the fourth leading cause of death in Kazakhstan. Cigarette smoking is a prevalent risk factor for COPD. While quitting smoking is the preferred way to reduce COPD risk, literature suggests that heated tobacco products (HTP) might be a better option for people who cannot quit smoking. The aim of this paper was to analyze the long-term effects of shifting to HTP use in long- term smokers compared to continued combustible cigarettes (CC) use. Patients and methods: A cohort of 1200 participants (393 HTP and 807 CC) aged 40-59 years with a minimum of 10 pack-year smoking history were recruited and followed for five years. The functional outcomes compared between HTP, CC users and No-Smokers (NS, people who stopping smoking) included: (1) COPD Assessment Test (CAT); (2) post-bronchodilator lung function; (3) 6-minute walking distance (6MWD) test; and (4) metabolic syndrome components. Multivariable linear mixed models (MIXED) were used to compare functional outcomes between visits and to test associations between health outcomes and smoking type (HTP vs. CC vs. NS) over time. Results: Out of 1200 participants 830 (466 CC users, 248 HTP users and 116 No-Smokers) remained in the study by the fifth year of follow up. Linear mixed models showed HTP use was associated with better CAT scores and HDL cholesterol level compared to CC users. Lung function (FVC) decrease was significantly less in HTP users. FEV, 6MWD, waist circumference, fasting blood glucose, triglycerides and diastolic blood pressure significantly changes over time, but without between-group difference in dynamic. Conclusion: This study demonstrated that HTP users experienced it to a significantly lesser decrease in lung function by FVC compared to CC users over time (in time dependent model), while demonstrating better stable levels in other functional outcomes. The results of this study suggest that HTP might be a less deleterious alternative compared to CC in people with long history of CC use and who cannot quit smoking.