Inflammatory marker levels in children with tobacco smoke exposure

Background: Tobacco smoke exposure (TSE) has inflammatory and immunosuppressive effects which may be associated with altered levels of inflammatory markers and pediatric illnesses. Objective: The primary objective was to examine the associations of cotinine-confirmed and parent-reported child TSE patterns and discharge diagnoses with C-reactive protein (CRP), IL-8, and IL-10 in 0–11-year-old pediatric emergency department (PED) patients who lived with ≥ 1 smoker. Methods: Saliva samples were obtained from 115 children with a mean (SD) age of 3.5 (3.1) years during the PED visit (T0). Saliva was analyzed for cotinine, CRP, IL-8, and IL-10. Parents self-reported their children's TSE patterns; children's medical records were reviewed to identify and categorize discharge diagnoses. Linear regression models were utilized to find T0 associations of cotinine-confirmed and parent-reported child TSE patterns, and PED diagnoses with each inflammatory marker. All models were adjusted for child race/ethnicity, child sex, annual household income, and housing type. The TSE models also adjusted for child discharge diagnosis. Results: At T0, the geometric mean (GeoM) of cotinine was 4.1 ng/ml [95 %CI = 3.2–5.2]; the GeoMs of CRP, IL-8, and IL-10 were 3,326 pg/ml [95 %CI = 2,696–4,105], 474 pg/ml [95 %CI = 386–583], and 1.1 pg/ml [95 %CI = 0.9–1.3], respectively. Parent-reported child TSE patterns were positively associated with ln-transformed CRP levels, while adjusting for the covariates (β^ = 0.012 [95 %CI:0.004–0.020], p = 0.037). In the parent-reported child TSE pattern model, there were significant positive associations between the covariate of child age with CRP and IL-8 levels (p = 0.028 and p < 0.001, respectively). Children with a bacterial diagnosis had higher IL-8 levels (p = 0.002) compared to the other diagnosis groups. Conclusions: Results indicate that parent-reported child TSE increases the expression of CRP in ill children and supports prior work demonstrating that IL-8 is higher in children with TSE who have bacterial infections. These findings should be examined in future research with ill children with and without TSE.