[Is reduction of tobacco consumption associated with reduced risk of cardiovascular and pulmonary mortality and morbidity?]

Introduction: Smokers without an intention to completely quit smoking often try to reduce their daily tobacco consumption. However, smoking reduction is not associated with reduced risk of all-cause mortality. The aim of this systematic literature review of data was to expose relations between reduction of daily tobacco consumption and a potential decrease in the risks of cardiovascular and pulmonary mortality and morbidity.
Method: Medline, on the period 1980-2018 with the following keywords: "smoking reduction", "harm reduction", "mortality", "morbidity", "cardiovascular disease ^* ", myocardial infarction", "coronar ^* ", "stroke", "lung cancer", "COPD", "chronic obstructive pulmonary disease", "asthma", "pulmonary disease ^* " and "respiratory disease" limits "title/abstract"; the selected languages were English or French. Among 158 articles, 32 abstracts have given use to a dual reading to select 19 studies.
Results: Reduction of daily tobacco consumption by at least 50% is not associated with (1) reduced risk of cardiovascular mortality and morbidity and (2) reduced risk of lung cancer mortality. Results of studies on the risk of lung cancer morbidity are conflicting. Smoking reduction by at least 50% has no or little effect on the incidence of chronic obstructive pulmonary disease (COPD) and FEV1 decline. In asthmatic patients, smoking reduction is associated with small improvement for night use of short acting beta2-agonists, doses of inhaled corticosteroids and bronchial hyper-reactivity.
Conclusion: Smoking cessation is the only effective strategy to reduce the harm caused by tobacco smoking. This finding should lead clinicians to offer support to smokers in order to assist them to completely quit smoking.
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