Rigotti NA, Harrington KF, Richter K, Fellows JL, Sherman SE, Grossman E, Chang Y, Tindle HA, Ylioja T. Increasing prevalence of electronic cigarette use among smokers hospitalized in 5 US cities, 2010-2013. Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco. 2015 Feb;17(17). 236-44. PMID: 25168031 [PubMed]
Little is known about the pattern of electronic cigarette (e-cigarette) use over time or among smokers with medical comorbidity.