These results should be considered in light of a number of limitations. First, our sample was limited to Swedish individuals, and the generalizability of these results to other populations is not known. Second, our measures of ND did not take into consideration the fact that many individuals use both cigarettes and snus, and could thus have higher levels of ND than they were assigned in these analyses. However, post-hoc analyses suggest that, among individuals who use both types of tobacco, few would be classified as having a different level of ND had we employed a more global assessment of dependence. Third, our data were cross-sectional and retrospective, and may be subject to errors in recall.
