Use of the Fagerström test to assess differences in the degree of nicotine dependence in smokers from five ethnic groups: The HELIUS study

Abstract

BackgroundThe prevalence of smoking varies across ethnic groups in developed countries, but little is known about ethnic variations in specific aspects of nicotine dependence (ND). We conducted item-response analyses in current smokers to compare ND factors across five ethnic groups. MethodsData were obtained from a population-based, multi-ethnic cohort study conducted in the Netherlands. The Fagerström Test for Nicotine Dependence (FTND) was assessed in 1147 Dutch, 991 South-Asian Surinamese, 1408 African Surinamese, 1396 Turkish, and 584 Moroccan smokers (N = 5526). We tested whether the factorial structure of the FTND was invariant across ethnic groups using a multi-group confirmatory factor analysis. FTND item and total scores and factor means were compared across groups. ResultsThe two-factor model representing “morning smoking” and “smoking patterns” provided an adequate fit. The items “Cigarettes smoked daily” and “Time until first cigarette” showed differential item functioning (DIF) as a function of ethnicity. Three out of four ethnic minority groups scored significantly higher on both factors compared to the Dutch origin group (all p < 0.001) before and after taking DIF into account, while the African Surinamese scored higher only on “morning smoking” when DIF was accounted for. DiscussionThe factor structure of the FTND is not measurement invariant across ethnic groups in this population-based sample. Accounting for DIF affecting the nicotine dependence factor scores, although South-Asian Surinamese, Turkish, and Moroccan groups showed higher levels of dependence than the Dutch origin group, genetic as well as environmental factors may account for the observed differences.