Background:
In a previous cross-sectional study, we developed a marketing receptivity index (MRI), which had independent, positive associations with positive smoking expectancies, smoking susceptibility and current smoking behavior in a sample of early adolescents in Argentina. The current study aimed to assess the predictive validity of the MRI.

Methods:
Data come from a longitudinal, school-based survey conducted in 33 secondary schools in Argentina. We included students who had never smoked at baseline and were successfully followed up approximately 17 months later (n=1700). Marketing receptivity was assessed with questions in three domains: frequency of going to stores that sell tobacco; cued recall of brand names for 3 cigarette packages with brand name removed; and ownership of branded merchandise. A four-level MRI was derived (low PoS marketing exposure only; high PoS exposure or recall of 1 brand; recall of 2 or more brands; and ownership of branded merchandise). Self-report of having tried to smoke at follow-up (i.e., initiation) was the primary outcome assessed. Logistic models regressed smoking initiation on the MRI, the MRI components (considered separately), and willingness to try one of the brands shown in the cued recall task, adjusting for sociodemographics, social influences and sensation seeking.

Results:
The 4 level MRI had independent positive associations with smoking initiation (AOR_{2 vs. 1}=1.42, 95% CI=1.12-1.79; AOR_{3 vs 1}=2.04, 95% CI=1.38-3.00; AOR _{4 vs. 1}=2.16, 95% CI=1.21-3.82). The index components, analyzed separately, were associated with outcomes except for ownership of branded merchandise. Willingness to try one of the brands shown in the recall task was also associated with initiation (AOR=1.73, 95% CI=1.31 - 2.28).

[Predictors of smoking initiation among secondary s]



Conclusions:
The marketing receptivity index and its component were associated with cigarette trial, suggesting its predictive validity and utility for future studies. Ownership of branded merchandize may be more useful for studying smoking progression amongst those who have already tried smoking.