Characterizing ENDS use in young adults with ecological momentary assessment: Results from a pilot study.

INTRODUCTION: Ecological Momentary Assessment (EMA) allows for assessment of electronic nicotine delivery systems (ENDS) use in real-time. This EMA study aimed to 1) describe study participation rates; 2) evaluate the concordance of EMA and survey items measuring frequency and quantity of ENDS use; and 3) assess the relationships between EMA items measuring frequency and quantity of ENDS use with ENDS dependence, measured at baseline and with saliva cotinine collected at follow-up. METHODS: Fifty young adult ENDS users completed baseline surveys, EMAs (i.e., random, event-based, daily diaries), and follow-up questionnaires over a 14-day period. Spearman correlations were conducted to determine concordance of survey items. Linear regression models assessed the relationships between EMA ENDS use characteristics (e.g., puffs, number of days used, quantity of e-liquid) with dependence items at baseline and saliva cotinine at follow-up. RESULTS: Overall completion for the prompted EMAs (random and daily diaries) was 68%. Correlations between EMA measures assessing ENDS use ranged from weak (ρ = -0.02; NS) to strong (ρ = 0.69, p < .001); EMA to follow-up items ranged from weak (ρ = 0.16; p < .05) to moderate (ρ = 0.54; p < .001). Significant associations were found between ENDS use measured via random and daily diary EMAs and saliva cotinine at follow-up after controlling for cigarette smoking (B = 0.70-1.76; p < .01), but not for event-based EMAs. Items measuring frequency/quantity of use from random EMAs were consistently associated with ENDS dependence at baseline (B = 0.74-1.58; p < .01). CONCLUSION: EMA represents a promising methodology to capture real-time ENDS use behaviors, primarily through daily diary and random EMAs.