BACKGROUND: The added value of fractional exhaled @entity842 (Feno) remains controversial in the investigation of @entity7446 ( @entity7446 ). OBJECTIVE: We sought to assess whether or not the increase of Feno levels following positive specific inhalation challenge (SIC) was restricted to phenotypes of subjects sharing common clinical characteristics by using a statistical cluster analysis. METHODS: Subjects were investigated for possible @entity7446 in a tertiary center using SICs from 2006 to 2012. Feno levels and sputum eosinophil counts were assessed at baseline and 24 hours after SIC. We performed a 2-step cluster analysis of the subgroup of subjects with @entity7446 . A  multivariate logistic regression was performed in order to identify the variables associated with an increase in Feno in subjects with @entity7446 . RESULTS: One hundred and seventy-eight subjects underwent SIC; 98 had a positive test. The cluster analysis performed in the @entity7446 subgroup identified 3 clusters. Despite a positive SIC, there was no increase in the Feno levels after exposure to occupational agents in Cluster 3, in which subjects were only exposed to low-molecular-weight (LMW) agents. The molecular weight of the agent (high molecular weight vs LMW) was the  only factor associated with an increase in Feno (OR: 4.2 [1.1-16.8]) in subjects with a positive SIC. CONCLUSION: An increase in Feno after exposure to agents causing @entity7446 seems to occur more consistently in subjects with @entity7446 caused by high molecular weight than in those with @entity7446 due to LMW.

Occupational asthma phenotypes identified by increased fractional exhaled XXXX after exposure to causal agents.

@entity7446 :: ('MESH:D059366', 'Disease') :: ['occupational asthma', 'OA'] @entity842 :: ('MESH:D009569', 'Chemical') :: ['nitric oxide']
@entity842 :: (MESH:D009569,Chemical) :: ['nitric oxide']
