UCSF

Background

Cigarette smoking is associated with an increased risk of developing ARDS. However, whether changes in smoking patterns or processes of care impact this relationship is unclear.

Research question

Are changes in smoking and resuscitation patterns associated with changes in the relationship between smoking and ARDS?

Study design and methods

We conducted a prospective cohort study of critically injured adults with blunt trauma from 2005 to 2015. Plasma cotinine, a tobacco biomarker, was measured to categorize patients by smoking status. We used regression to assess the relationship between smoking, resuscitation practices, and ARDS over time.

Results

In the overall cohort, active (OR, 1.9; 95% CI, 1.0-3.5; P = .046) and passive (OR, 2.6; 95% CI, 1.4-4.8; P = .002) smoking were associated with an increased risk of developing ARDS in multivariate analyses. In contrast to the dose-response relationship in patients enrolled from 2005 to 2008, passive cigarette smoke exposure was associated with the highest risk of developing ARDS in patients enrolled from 2009 to 2015, suggesting a threshold effect. Packed RBC (pRBC) and fresh frozen plasma (FFP) transfusions were associated with an increased risk of developing ARDS, particularly in active smokers (pRBC: OR, 5.6; P < .001; FFP: OR, 4.5; P < .001) compared with passive smokers or nonsmokers. Blood product transfusion and smoking patterns changed over time.

Interpretation

Despite changes in resuscitation and smoking patterns, cigarette smoking remains associated with an increased risk of developing ARDS. However, this relationship changed over time, with passive smokers at particularly increased risk of developing ARDS in later years, which may be related to changes in smoking patterns or transfusion practices over time. These findings highlight the need for additional mechanistic and epidemiologic studies of the effects of low levels of cigarette smoke exposure on lung health.