Table. 1—

Assessment of potential contributing factors to frequent exacerbations in difficult-to-treat asthma

Ongoing allergen exposure
 Specific IgE to HDM, UniCAP ≥3 and living in HDM-rich environment
 Specific IgE to any pet while having the same pet at home
Food allergens
 UniCAP food mix ≥2
 Present use of salicylates, NSAIDs, β-blockers or ACE inhibitors
Occupational (low molecular weight) sensitisers
 Increased symptoms at work and exposure to known sensitiser, currently or in past
Severe chronic sinus disease
 Indication for nasal sinus surgery by ENT specialist
Gastro-oesophageal reflux
 Pathological reflux at 24-h pH measurement#
 Symptomatic improvement after a trial of proton-pump inhibitors
Recurrent (bacterial) respiratory infections
 Requirement of ≥3 antibiotic courses in last 2 yrs
Relative immune deficiency
 Pathologically decreased levels of IgG subclasses, IgA subclasses or IgM
 Pathologically increased level of free thyroxin (FT4 >24 pmol·L−1) in peripheral blood
Obstructive sleep apnoea syndrome
 Documented abnormality at polysomnography or history of snoring with apnoeas >10 s
Hormonal influences
 History of increased symptoms premenstrually, during pregnancy or at menopause
Psychological dysfunctioning
 General Health Questionnaire-12 score ≥6+
Poor inhaler technique
 ≥2 errors out of 8 essential elements of proper medication inhalation+
  • Ig: immunoglobulin; HDM: house dust mite; NSAID: nonsteroidal anti-inflammatory drug; ACE: angiotensin converting enzyme; ENT: ear nose and throat. #: 24-h pH measurement was performed in 39 patients; : level below lower/above upper limit of normal values used in the current authors' laboratory; +: for details about questionnaire/checklist see Methods section.