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.
“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.”
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.