Main outcomes at twelve months.

SD = Standard deviation. P<0.01 for the comparison * Tobacco only vs electronic cigarettes only ** Tobacco only vs both tobacco and electronic cigarettes (dual smoking) *** E-cigarettes only vs both tobacco and electronic cigarettes (dual smoking). € EuroQol final item, ranging from 1 (feel very bad) to 10 (perfectly healthy). ψ Chronic obstructive pulmonary diseases, stroke, heart failure, myocardial infarction, angina, pneumonia, cancer of: larynx or oral cavity, lung, stomach, pancreas, cervix, kidney, bladder, myeloid leukaemia. Main outcomes at twelve months.