Assessing the association between cigarette smoking and blood C-reactive protein levels using restructured cohort data.

Introduction: Cigarette smoke exposure is known to induce inflammation, leading to elevated levels of inflammatory markers such as white blood cell (WBC) count and C-reactive protein (CRP). Despite extensive research on this relationship, longitudinal studies are limited. We aimed to explore the association between cigarette smoke exposure and WBC count and CRP levels by restructuring community cohort data.

Methods: Data from a community cohort of the Korean population, followed biennially from 2001 to 2018, were utilized. Smoking status was determined through self-administered questionnaires. WBC and CRP levels were measured in a central laboratory with stringent quality control. Cohort data were restructured into pairs representing before and after measurements. We analyzed smoking effects on WBC and CRP using pairwise before-after tests based on changes in smoking status. Furthermore, parallel group analyses comparing changes in smoking status to no change were conducted.

Results: Analysis included 4336 pairs for WBC and 3068 pairs for CRP from 10,030 participants. Pairwise analysis showed a significant decrease in WBC transitioning from current smoker to non-smoker and an increase from non-smoker to current smoker. Parallel group analysis demonstrated a significant decrease in WBC transitioning from current smoker to non-smoker compared to remaining current smoker, and an increase from non-smoker to current smoker compared to remaining non-smoker. CRP did not exhibit significant associations in either analysis.

Conclusions: In a community cohort, cigarette smoking was associated with elevated WBC count. However, CRP levels did not consistently reflect inflammation associated with cigarette smoking.