An item response theory analysis of nicotine dependence symptoms in recent onset adolescent smokers.

Abstract

Given absence of a "gold standard" for measuring self-reported nicotine dependence, particularly among less experienced smokers, there is a need to evaluate existing measures to determine how well symptoms measure the underlying nicotine dependence construct and whether symptoms function differently for less experienced smokers. Study aims were to determine (1) likelihood of endorsement of individual symptoms at different levels of a nicotine dependence construct and the ability of symptoms to discriminate between different levels of this construct and (2) whether these symptom properties varied between nondaily and daily smokers. We used multiple group item response theory analysis to evaluate nicotine dependence symptoms from the nicotine dependence syndrome scale based on a nationally representative sample of 8081 recent onset adolescent smokers from the national surveys on drug use and health. After controlling for age, gender, smoking quantity and length of smoking exposure, symptoms assessing tolerance were invariant across nondaily and daily smokers, and discriminated well between levels of the nicotine dependence construct. However, the majority of symptoms functioned differently for nondaily and daily smokers. These symptoms did not discriminate as well between levels of the nicotine dependence construct and were more likely to be endorsed at lower levels of this construct for daily smokers. A measure that encompasses a range of symptoms tapping different aspects of smoking may be ideally suited for nondaily adolescent smokers, while an ideal measure of nicotine dependence for daily smokers might also include more core diagnostic features of nicotine dependence such as withdrawal and tolerance.