Secondhand smoke is associated with more frequent hospitalizations in children with sickle cell disease

Tobacco smoke exposure has been associated with more frequent hospitalizations in children with sickle cell disease (SCD), but previous studies have not quantified the exposure by objective methods. We enrolled 50 children and young adults with SCD in a retrospective and prospective cohort study and quantified tobacco smoke exposure by objective (salivary cotinine) and survey measures. We used a multivariable negative binomial regression model to evaluate the association between salivary cotinine and hospital admissions. Forty-five percent (22/49) of participants had significant elevation of salivary cotinine (≥ 0.5 ng/ml). The incidence risk ratio (IRR) for hospital admission for those with elevated cotinine was 3.7 (95% CI 1.8-8). Those exposed to secondhand smoke but not primary smokers (cotinine between 0.5 and 10 ng/ml) had a similarly increased risk of hospitalization [IRR 4.3 (95% CI 1.8-10)]. We show that an objective measure of tobacco smoke exposure, salivary cotinine, is strongly associated with the rate of hospital admissions in children and young adults with SCD. This association underscores the importance of screening for tobacco smoke exposure in people with SCD. Further investigation is warranted to determine the mechanisms of and to evaluate interventions to decrease tobacco smoke exposure.