Third, the amount of tobacco in a RYO cigarette is variable, and this contributes to an imprecise estimation of the number of cigarettes. they Some reports have used conversion factors between 0.6 and 0.9 g per cigarette,5

13 22 24 and according to the Pricing Policy And Control of Tobacco in Europe (PPACTE) project in 2010, the median weight of RYO cigarettes ranged between 0.48 and 1.15 g.29 In our study, we used three different options (0.5, 0.8 and 1 g). Fourth, pipe tobacco can be also used to make RYO cigarettes, so their unitary estimations may be slightly underestimated, although less than 1% of the Spanish population smoked pipes.30 Despite this, our analysis allowed us to provide an estimation of tobacco sales (and tobacco consumption) at a national level and, more importantly, allowed us to compare the consumption of manufactured and RYO cigarettes. We have used a well-established time-series methodology to assess cigarette consumption over time. The statistical modelling through Bayesian autoregressive assumption appears a useful method to assess the long-run relationship between manufactured and RYO cigarettes. Moreover, the net estimations of manufactured and RYO cigarettes

according to the constraints of the Bayesian model were similar to the data observed per year (see online supplementary table S1). In conclusion, although the sales of manufactured cigarettes are decreasing as observed in the past years in Spain, use of RYO cigarettes is progressively increasing. Rolling tobacco sales will continue to increase in the next years, partly due to a shift in the consumption from manufactured

to RYO cigarettes. More attention should be paid to this and other alternative tobacco products in order to hinder its access, especially to young people. More concrete strategies, such as higher taxation and information on their health effects, are key strategies to be developed, with emphasis on specific populations. Footnotes Contributors: JMMS and EF conceived the study. MF, RC and JMMS prepared the database Carfilzomib and conducted the analyses. All the authors contributed substantially to the interpretation of the data. MF drafted the first version of the manuscript; all the authors contributed to its subsequent versions and approved the final version. EF is the guarantor. Funding: This work was supported by the Instituto de Salud Carlos III, Government of Spain (RTICC RD12/0036/0053 and BAE 14/00014) and the Ministry of Universities and Research, Government of Catalonia (grant 2009SGR192). Competing interests: None. Provenance and peer review: Not commissioned; externally peer reviewed. Data sharing statement: No additional data are available.
Evidence-based medicine (EBM) is the “integration of best research evidence with clinical expertise and patient values”1 2 and is widely promoted as a tool to improve patient care.