Comparison of the health-related outcomes for traditional cigarettes, e-cigarettes, heat-not-burn cigarettes and snus: a systematic review and meta-analysis

Tobacco products using is a global public health problem. The aim of this systematic review and meta-analysis was to assessed the health-related outcomes associated with acute and chronic using of traditional cigarettes (TCs), e-cigarettes (ECs), heated tobacco products (HTPs) and snus. PubMed, EMBASE, Web of Science, Scopus and the Cochrane Central Register of Controlled Trials databases were searched by the terms: ‘cigarette’, ‘conventional cigarette’, ‘ENDS’, ‘electronic nicotine delivery system’, ‘electronic cigarette’, ‘e-cigarette’, ‘heat-not-burn product’, ‘heat-not-burn cigarette’, ‘tobacco heating product’, ‘heated tobacco product’, ‘snus’, ‘Swedish snuff’, ‘oral nicotine pouches’, ‘nicotine pouches’, ‘health’, ‘health effect’, ‘health impact’. Random effects model was used to calculate effect sizes. I2 statistic was used to evaluate the heterogeneity of studies. Funnel plot and Egger’s regression test were used to assess publication bias. Statistical analysis of the data was performed in R (version 4.2.2). Acute exposure to analyzed tobacco products significantly affects heart rate (MD = 6.78; 95% CI [4.86; 8.69]; p < 0.0001; I2 = 49%). Chronic exposure to such tobacco products significantly affects triglycerides level (MD = 18.09; 95% CI [6.12; 30.07]; p = 0.003; I2 = 62%), systolic blood pressure (MD = 6.99; 95% CI [1.62; 12.37]; p = 0.01; I2 = 78%) and diastolic blood pressure (MD = 5.2; 95% CI [2.27; 8.13]; p = 0.0005; I2 = 54%). There was a greater odds of cancer with chronic smoking by 32% (OR = 1.32; 95% CI [1.08; 1.61]; p = 0.009; I2 = 92%). We have shown that former smokers have a 5% higher chance of developing cancer, while current smokers have an increased chance by as much as 61%. Robust evidence supports adverse health effects of traditional cigarettes, whereas evidence for alternative products remains limited and heterogeneous. Therefore, longitudinal studies involving individuals exclusively using conventional and alternative tobacco products should be performed in the future. The study protocol of this systematic review was registered in International Prospective Register of Systematic Reviews (PROSPERO) with registration number CRD420251062406.