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J Bras Pneumol. 2007 Sep-Oct;33(5):495-501.

Investigation of factors associated with difficult-to-control asthma.

[Article in English, Portuguese]

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Department of Clinical Medicine, Faculdade de Medicina de Ribeiro Preto da Universidade de São Paulo - FMRP/USP, Universityof São Paulo at Ribeirão Preto School of Medicine - Ribeirão Preto (SP) Brazil.



To determine the prevalence of factors associated with difficult-to-control asthma.


Patients with severe asthma were selected from the outpatient asthma clinic of the Ribeirão Preto School of Medicine Hospital das Clínicas. The patients were divided into two groups: controlled severe asthma and difficult-to-control severe asthma. After new attempts to optimize the severe asthma treatment, a questionnaire was applied, and additional tests for factors associated with difficult-to-control asthma, such as environmental and occupational exposure, smoking history, social factors, rhinitis/sinusitis, gastroesophageal reflux disease (GERD), obstructive sleep apnea, congestive heart failure (CHF), pulmonary embolism, cystic fibrosis, vocal cord dysfunction, alpha-1 antitrypsin deficiency, and Churg-Strauss syndrome, were performed.


77 patients with severe asthma were selected, of which 47 suffered from hard-to-control asthma, being 68.1% female, with mean age of 44.4 years (+/-14.4), and forced expiratory volume in one second of 54.7% (+/-18.3). The most factors most often associated with difficult-to-control asthma were noncompliance with treatment (68%), rhinitis/sinusitis (57%), GERD (49%), environmental exposure (34%), occupational exposure (17%), smoking history (10%), obstructive sleep apnea (2%), and CHF (2%). At least one of these factors was identified in every case.


Noncompliance with treatment was the factor most often associated with difficult-to-control asthma, underscoring the need to investigate comorbidities in the evaluation of patients with this form of the disease.

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