Comparisons of dependence on cigarettes and e-cigarettes: data from the path study
An Item-Response-Theory-based dependence scale, developed on PATH data, assesses e-cigarette dependence, and for the first time allows for direct comparison of dependence across products. Data were from adult established users of e-cigarettes (ECIG) and/or cigarettes (SMOK; and no other tobacco) in PATH (Wave 1), a representative survey of the US. Dependence on SMOK and ECIG was contrasted across groups defined by history of use of each product (current users or quit in past year, N=7,625). Among established users of both SMOK and ECIG, dependence was much higher on SMOK; this was true both among current (SMOK: mean=3.11 [SE=0.05] vs. ECIG =1.61 [0.04], p<0.0001) and former users (SMOK =1.59 [0.12] vs. ECIG =1.11 [0.04], p=0.0001). Current smokers who reported currently using ECIG were more SMOK-dependent than never-users of ECIG (ECIG =3.07 [0.03] vs. never ECIG =2.69 [0.02], p<0.0001). Among current ECIG users, those who had quit smoking in the past year reported greater ECIG dependence than those who were still smoking, but their ECIG dependence was significantly lower than the SMOK dependence of current smokers, whether they currently used ECIG, had quit ECIG, or never used ECIG. In direct within-person comparisons between cigarettes and e-cigarettes, e-cigarettes were associated with less dependence. Greater cigarette dependence was seen in smokers who used e-cigarettes than in those who did not; more dependent smokers may gravitate to and stay with e-cigarettes. The highest level of e-cigarette dependence was seen in those who had quit smoking in the past year; heavier e-cigarette use is associated with smoking cessation. These people may have transferred their nicotine dependence from cigarettes to e-cigarettes, as hoped for by harm-reduction advocates.