Prevalence of bronchiectasis in asthma according to oral steroid requirement: influence of immunoglobulin levels.

PURPOSE

To establish the prevalence of bronchiectasis in asthma in relation to patients' oral corticosteroid requirements and to explore whether the increased risk is due to blood immunoglobulin (Ig) concentration.

METHODS

Case-control cross-sectional study, including 100 sex- and age-matched patients, 50 with non-steroid-dependent asthma (NSDA) and 50 with steroid-dependent asthma (SDA).

STUDY PROTOCOL

(a) measurement of Ig and gG subclass concentration; (b) forced spirometry; and (c) high-resolution thoracic computed tomography. When bronchiectasis was detected, a specific etiological protocol was applied to establish its etiology.

RESULTS

The overall prevalence of bronchiectasis was 12/50 in the SDA group and 6/50 in the NSDA group (p = ns). The etiology was documented in six patients (four NSDA and two SDA). After excluding these patients, the prevalence of bronchiectasis was 20% (10/50) in the SDA group and 2/50 (4%) in the NSDA group (P < 0.05). Patients with asthma-associated bronchiectasis presented lower FEV1 values than patients without bronchiectasis, but the levels of Ig and subclasses of IgG did not present differences.

CONCLUSIONS

Steroid-dependent asthma seems to be associated with a greater risk of developing bronchiectasis than non-steroid-dependent asthma. This is probably due to the disease itself rather than to other influencing factors such as immunoglobulin levels.