RESUMEN
BACKGROUND: Most adults who regularly use e-cigarettes or Electronic Nicotine Delivery Systems (ENDS) desire to discontinue use. ENDS use can result symptoms of nicotine withdrawal and dependence which can make it more difficult to discontinue use. Brief, valid assessment of nicotine dependence among adults who use ENDS is needed to guide treatment for nicotine dependence in this group. We sought to develop a brief, valid instrument to measure nicotine dependence among adults seeking to discontinue ENDS in a busy Quitline. METHODS: In this cross-sectional design, we examined content, construct, and concurrent validity of the Roswell ENDS Nicotine Dependence Scale (Roswell eND Scale) and the Penn State E-Cigarette Dependence Index (Penn State eCDI). Participants who called the New York Quitline from November 2019 to June 2020 seeking to discontinue ENDS use were invited to participate. Construct validity was examined with exploratory and confirmatory factor analyses. Instrument and factor scores were then correlated with cotinine, a biomarker of nicotine exposure. RESULTS: All participants (n = 209) were highly dependent and co-used combustible cigarettes to varying degrees. Both instruments demonstrated content validity and construct validity, however only the 5-item Roswell eND Scale demonstrated criterion-related validity by showing a significant positive correlation with salivary cotinine levels. CONCLUSIONS: The 5-item Roswell eND Scale can briefly and effectively assess nicotine dependence among treatment-seeking adults who co-use ENDS and cigarettes. These preliminary psychometric findings have the potential to be generalizable to other adults seeking to discontinue ENDS use, many of whom currently or formerly smoked cigarettes.