Are smokers “hardening” or rather “softening”? An ecological and multilevel analysis across 28 European Union countries

Background Tobacco control policies can reduce smoking prevalence. These measures may be less effective where smoking prevalence has significantly declined, as the remaining smokers have “hardened”. Our aim was to empirically evaluate the “hardening hypothesis” at the population-level in the European Union (EU) and explore factors associated with hardcore smoking. Methods We conducted two separate analyses in the EU using data on smoking from the Eurobarometer surveys (2009–2017, n=112 745): a) A panel-data fixed-effects linear regression to investigate changes over time in the percentage of hardcore smokers in relation to standardized smoking prevalence at the country-level. b) A multilevel logistic regression analysis with hardcore (daily smokers, ≥15 cigarettes per day (cpd) that have not attempted to quit in the last 12 months) and light (