Changes in Respiratory Function and Physical Capacity among Smokers after Switching to IQOS: One Year Follow-Up

Background: Combustible cigarettes (CC) smoking is a common risk factor for chronic obstructive pulmonary disease (COPD), which is the fourth leading cause of death in Kazakhstan. Switching to “heat-not-burn” tobacco products (IQOS) has been shown to have less deleterious health effect compared to CC for those who cannot quit smoking. The goal of the study was to explore respiratory and physical effects of switching from CC to IQOS in a population of long-time smokers in Kazakhstan. Methods: Two cohorts of men and women aged between 40 and 59 residing in Almaty (a large two-million city of Kazakhstan) were recruited into two cohort of 801 CC smokers and 400 IQOS users and matched by gender, age, education, and smoking history. Analyses also included 627 CC smokers and 308 IQOS users who maintained their tobacco product use during the first year of observation. Spirometry measurements and the 6-minute walk test (6MWT) were performed as a part of the baseline and one-year comprehensive assessments. In addition to spirometry, clinical assessments included components of metabolic syndrome and anthropometry. For comparative analysis between two cohorts Student’s t-test and Chi-squared tests were used. Results: We observed significantly better outcomes for IQOS users in most of CAT scores, spirometry outcomes, and in some metabolic syndrome components. Although changes in the results between the baseline and the one-year assessments show comparable results, smokers of CC often show significantly faster decline in the health status compared to IQOS. Specifically, the changes in CAT score and in spirometry FEV1 over FVC ratios were worsening at higher pace for CC smokers compared to IQOS users. Conclusions: After one year of observation IQOS users demonstrated better outcomes for most of CAT scores and in the ratio of FEV1 over FVC in comparison to CC smokers.