In contrast to previous in silico modeling studies, ventilation abnormalities do not appear randomly distributed among patients with asthma, and may persist in the same lung regions during a prolonged period. These findings were published in CHEST.

In a case study, researchers prospectively followed-up nonidentical female adult twins with lifelong asthma for 2 study visits between January 2010 and March 2017. Pulmonary magnetic resonance imaging, computed tomography imaging, and pulmonary function tests were used to prospectively evaluate the patients during this 7-year period.

Twins had parents who were heavy tobacco smokers in the home, and both parents had a history of airway disease. Different asthma specialists independently prescribed the twins 400 μg daily budesonide combined with formoterol (patient 1: once-daily 200/6 μg 2 puffs; patient 2: twice-daily 200/6 μg 1 puff). Both patients reported weak to moderate controller medication adherence.

At baseline, each twin demonstrated spatially identical focal ventilation defects, and both twins showed left-sided upper lobe ventilation abnormalities at follow-up. Patients had a similar subsegmental airway wall area percentage at follow-up (71% in patient 1 and 75% in patient 2), which the researchers found substantially abnormal, based on the published literature.

Fewer airways were found in patient 2 vs patient 1 (166 vs 202, respectively), as demonstrated in airway number by airway tree generation distal to left-sided upper lobe apicoposterior bronchopulmonary segment and right-sided upper lobe apical bronchopulmonary segment.

Limitations of the study included using only 2 time points for evaluation and the lack of adjustment for shared genetics or in utero events.

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“If ventilation defects occur randomly in patients with asthma,” the researchers wrote, “the probability of this occurring in both patients in the same location, twice over 7 years, is approximately one in 130,000 people.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Eddy RL, Matheson AM, Svenningsen S, et al. Nonidentical twins with asthma: spatially matched CT airway and MRI ventilation abnormalities. CHEST. 2019;156(6):e111-e116.