Adolescent nicotine dependence measured by the modified Fagerstrom tolerance questionnaire at two time points

Within the framework of a computer-assisted smoking prevention and cessation program, high school students completed a modified version of the Fagerstrom Tolerance Questionnaire (FTQ) as part of two in-class computerized survey sessions (Sessions I and II) spaced two months apart. Seventy-eight 10th, 11th and 12th grade smokers (at least 1 cigarette/week) who have completed both computer sessions were included in the analysis. Individuals who changed the number of cigarettes smoked between Sessions I and II were considered to have shifted their "true score" on nicotine dependence. No proxy item for nicotine dependence was available in the survey, so the item "How many cigarettes do you smoke a day?" was extracted from the modified FTQ to serve as the proxy item; thus, the analysis of test-retest reliability was based on 6 FTQ items. The test-retest analysis was restricted to students whose number of cigarettes per day did not vary across time points (n = 51). Principal components analysis on the 7-item FTQ resulted in a single dimension, accounting for 49.6% of the total variance. The Ci-item FTQ also appears to be unidimensional, explaining 52.5% of the total variance. The computed component loadings support equal rather than differential item weighting. Corrected item-total correlations for the 7-item scale ranged from 0.47 to 0.73; for the 6-item FTQ, the corrected item-total correlations ranged from 0.45 to 0.71. Although the modified 6-item FTQ revealed sufficient stability over a two-month interval, with a test-retest correlation of 0.71, future research should include the development of items that better reflect adolescent smoking patterns. Limitations of the study are discussed.