Late respiratory effects of sulfur mustard: how is the early symptoms severity involved?

The association between severity of exposure to sulfur mustard (SM) and late respiratory complications is not clear. The aim of this study was to determine the presence of late pulmonary complications in patients with mild, moderate, and severe initial symptoms of sulfur mustard exposure. This was a retrospective cohort study on patients with mild, moderate, and severe initial symptoms of sulfur mustard exposure (during 1983-1988) in Baqyatallah University of medical sciences (2004-2005). The 'mild' group (n = 115) had no early symptom at the time of exposure. The 'moderate' group (n = 273) had early symptoms after exposure and were not hospitalized for that reason. The 'severe' group (n = 215) had early symptoms and had been hospitalized accordingly. Pulmonary function tests and high-resolution computed tomography of the chest were performed. The chi-square test was used for data analysis. The severe and moderate groups had a similar frequency of obstructive pattern (21%), whereas only one patient in the mild group showed this pattern. Air trapping did not significantly differ between groups. In the mild group, 74.8% (n = 86) showed significant air trapping, whereas it was 62.3% (n = 170) in moderate and 67.0% (n = 144) in severe groups (P = 0.057). Moderate and severe exposure to sulfur mustard causes an equal risk of late pulmonary complications, while mild exposure has lesser risk. Bronchiolitis obliterans is the main underlying respiratory consequence of sulfur mustard exposures and may relate to host factors rather than to severity of early symptoms.