Table 4.

Diagnosis and clinical aspects^*

Non-WRA	Sensitizer-induced OA
Asthma Severity
Greater severity in those with associated rhinitis	Greater severity in those with associated rhinitis
Neutrophilic vs. eosinophilic airway inflammation associated with increased severity, worse lung function, less steroid responsiveness, but not related to nonspecific airway hyperresponsiveness.	Neutrophilic vs. eosinophilic airway inflammation associated with OA due to low-molecular-weight agents, in a noneosinophilic variant of OA and WEA, and with a poor prognosis.
Overlap with Chronic Obstructive Pulmonary Disease
∼10% overlap with chronic obstructive pulmonary disease.	Overlap to be evaluated in epidemiological studies of occupational chronic obstructive pulmonary disease.
Symptoms
	Work-related wheeze, nose, eye itching, and lack of hoarseness are the most sensitive symptoms in cases of OA due to high-molecular-weight agents.
Diagnostic Tests
Mannitol less sensitive than methacholine for challenges.	Mannitol challenge may differentiate subjects according to severity of disease.
FeNO is a surrogate marker of eosinophilic inflammation in asthma (rapid and less invasive).	FeNO may be useful in the interpretation of specific inhalation challenges in subjects who cannot produce satisfactory sputum samples.
Assessment of mediators in induced sputum can show aspects of airway inflammation and remodeling.
Specific bronchial challenges are seldom used in non-WRA.	Specific bronchial challenges are reference tests for diagnosing OA, although not used in many centers.

Definition of abbreviations: OA = occupational asthma; WRA = work-related asthma.

Similarities printed in bold. Features that differ or have only been only evaluated for one condition are not bold.

^*Irritant-induced asthma is not included here because these factors cannot be compared at present.