Introduction: Intermittent smokers (ITS) are an increasingly prevalent segment of smokers, yet it is unknown whether or how dependence severity may vary across ITS.
Methods: Participants were 217 ITS (70 never daily ITS [NITS], 138 converted ITS [CITS], and 9 unknown), who smoked 4-27 days per month, and 197 daily smokers (DS), recruited for a study on smoking patterns. Participants completed questionnaires on dependence (time to first cigarette after waking, Fagerström Test of Nicotine Dependence [FTND], Nicotine Dependence Syndrome Scale [NDSS], Wisconsin Inventory of Smoking Dependence Motives [WISDM], and Hooked on Nicotine Checklist [HONC]) and recorded each cigarette in real time over 3 weeks using Ecological Momentary Assessment. Logistic regression assessed differences in dependence between groups (DS vs. ITS; CITS vs. NITS), and least squares regression examined associations between dependence and smoking behavior (mean, maximum cigarettes per day; proportion of days smoked; longest period of abstinence) within ITS.
Results: As expected, DS were significantly more dependent than ITS: FTND, NDSS, and WISDM discriminated between ITS and DS with greater than 90% accuracy. Similarly, among ITS, NITS demonstrated lower dependence than CITS. Within ITS, dependence measures also correlated with observed smoking rate and duration of abstinence.
Conclusions: The study confirmed that DS are more dependent than ITS and that CITS are more dependent than NITS. Importantly, ITS exhibit features of dependence, and there is meaningful variation in dependence within ITS, suggesting that some aspects of dependence may appear with very infrequent smoking. Future work should examine implications for ITS' potential progression to daily smoking and cessation outcome.