Time to first cigarette and serum cholesterol levels.

RATIONALE: Cigarette smoking is a primary cause of cardiovascular disease (CVD); however, prior research has rarely distinguished smoking behavior from nicotine dependence.

OBJECTIVE: The current study presents a novel investigation into whether time to first cigarette (TTFC), a reliable proxy for nicotine dependence, is associated with lipid cholesterol, a biomarker for CVD, after controlling for smoking behavior and other risk factors.

METHODS: In total, 3903 current adult smokers were drawn from four consecutive cross-sectional waves (2005-06, 2007-08, 2009-10, and 2011-12) of the National Health and Nutrition Survey (NHANES). Weighted regressions were used to examine whether earlier TTFC is associated with differences in a) numeric values; b) guideline-based binary outcomes of total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and the LDL/HDL ratio; and c) 10-year risk scores for CVD.

RESULTS: Earlier TTFC (within 5, 30, or 60 min vs. >60 min) was significantly (p < 0.05) associated with lower HDL (2-3 mg/dL) and a lower odds ratio (OR = 0.70) of having optimal HDL levels, and a lower LDL/HDL ratio (0.14-0.32); these results were consistent across three models (unadjusted, adjusted for smoking behavior, and also adjusted for demographics and other CVD risk factors). Earlier TTFC was also associated (p < 0.05) with higher odds of having sub-optimal total cholesterol levels (OR = 1.55) and higher LDL values (8 mg/dL), but only in the models adjusting for smoking behavior. However, the association of TTFC with 10-year CVD risk scores did not reach significance (p > 0.05).

CONCLUSION: More "addicted" smokers, as indicated by earlier TTFC, have less favorable lipid profiles, even after accounting for current and lifetime smoking history and other CVD risk factors. Future research should further explore whether TTFC could be a useful tool for refining clinically significant CVD risk among smokers.