title: Specific inhalation challenge: the relationship between response, clinical variables and lung function.
abstract: The specific inhalation challenge (SIC) is considered the gold standard for the diagnosis of occupational asthma (OA). However, its use is not standardised, and the intensity of exposure is regulated empirically. The aim of this study was to identify clinical variables and/or pulmonary function variables able to predict the scale of patients' response to SIC.
  
  
  
  All patients who underwent SIC at our centre between 2005 and 2013 were studied. Anthropometric characteristics, atopic status, type of causal agent, latency times, pulmonary function tests and SIC results were analysed.
  
  
  
  Two hundred and one patients (51% men) were assessed, of whom 86 (43%) had positive SIC. In the patients with positive results, 29 (34%) were exposed to high molecular weight (HMW) agents and 57 (64%) to low molecular weight (LMW) agents. Patients with a positive SIC exposed to HMW agents had a higher fall in FEV1after SIC compared with those exposed to LMW agents (p=0.036). The type of asthmatic reaction after SIC also differed between the groups (p=0.020). The logistic regression analysis showed that patients with a higher PC20before SIC were less likely to have severe decreases in FEV1 after SIC after adjusting for potential confounders (OR=0.771, 95% CI 0.618 to 0.961, p=0.021).
  
  
  
  The scale of the response to SIC is influenced mainly by the degree of bronchial hyper-responsiveness, regardless of whether the causative agent is HMW or LMW, or whether the response is early or late.
authors.affiliation: Pulmonology, Hospital General Universitario Morales Meseguer, Murcia, Spain.
authors.forename: Chunshao
authors.initials: C
authors.lastname: Hu
authors.affiliation: Servei de Pneumologia, Hospital Universitari Vall dHebron, Institut de Recerca (VHIR), Universitat Autnoma de Barcelona, Barcelona, Spain.|Respiratory, CIBER Enfermedades Respiratorias (Ciberes), Barcelona, Spain.
authors.forename: Maria-Jesus
authors.initials: MJ
authors.lastname: Cruz
authors.affiliation: Servei de Pneumologia, Hospital Universitari Vall dHebron, Institut de Recerca (VHIR), Universitat Autnoma de Barcelona, Barcelona, Spain.|Respiratory, CIBER Enfermedades Respiratorias (Ciberes), Barcelona, Spain.
authors.forename: Iñigo
authors.initials: I
authors.lastname: Ojanguren
authors.affiliation: Servei de Pneumologia, Hospital Universitari Vall dHebron, Institut de Recerca (VHIR), Universitat Autnoma de Barcelona, Barcelona, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: de Homdedeu
authors.affiliation: Department of Respiratory, Clinic University Hospital, Santiago de Compostela, Spain.
authors.forename: Francisco-Javier
authors.initials: FJ
authors.lastname: Gonzalez-Barcala
authors.affiliation: Servei de Pneumologia, Hospital Universitari Vall dHebron, Institut de Recerca (VHIR), Universitat Autnoma de Barcelona, Barcelona, Spain.|Respiratory, CIBER Enfermedades Respiratorias (Ciberes), Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Munoz
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000485:Allergens / Q000008:administration & dosage; D000886:Anthropometry; D059366:Asthma, Occupational / Q000175:diagnosis*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000175:diagnosis; D016273:Occupational Exposure / Q000009:adverse effects*; D012129:Respiratory Function Tests; D013030:Spain; D013147:Spirometry
chemical_list: D000485:Allergens
keywords: High-molecular-weight agents; Low-molecular-weight agents; Methacholine