Lung volume abnormalities more common in young patients with sickle cell anemia

Compared with healthy controls, young patients with sickle cell anemia demonstrated more abnormalities in lung volume via lung clearance index, according to study findings.

Michele Arigliani, MD, PhD, a fellow in the department of respiratory medicine at the UCL Great Ormond Street Institute of Child Health, London, and colleagues aimed to determine whether lung clearance index (LCI), intra-acinar ventilation inhomogeneity (S_acin) and conductive ventilation inhomogeneity (S_cond) are more frequently abnormal than lung volumes in young people with sickle cell anemia (SCA). They cross-sectionally assessed nitrogen multiple-breath washout (MBW), spirometry and body plethysmography at steady state in patients with SCA (hemoglobin SS) and healthy controls aged 8 to 21 years from London.

The study included 35 patients (51% male; mean age, 16.4 years) and 31 controls (48% male; mean age, 16.2 years). Participants were of Black African origin, which the researchers defined as African or Caribbean, and arms were matched for ethnic group and ± 1 year of age.

Researchers reported significant differences between study and control groups in the following metrics: mean LCI (mean difference, 0.42 units; 95% CI, 0.22-0.63), S_acin (mean difference, 0.014 units; 95% CI, 0.001-0.026), FEV₁ (mean difference, –0.79 z score; 95% CI, –1.28 to –0.3), FVC (mean difference, –0.8 z score; 95% CI, –1.28 to –0.31) and total lung capacity (mean difference, –0.76 z score; 95% CI, –1.25 to –0.29). However, there were no differences between groups in S_cond and FEV₁-to-FVC ratio.

Furthermore, 29% of patients had LCI greater than the 95th percentile of control subjects compared with 23% who had an abnormal FEV₁ of less than the 5th percentile of the reference population.

“This study showed that MBW is more frequently abnormal than spirometry and body plethysmography in young patients with SCA,” Arigliani and colleagues wrote. “We found mildly increased ventilation inhomogeneity in people with SCA, which appears to result in most cases from peripheral or parenchymal lung disease rather than obstructive disease.”

The researchers added that future studies should further investigate whether ventilation inhomogeneity is frequently abnormal in patients with SCA and whether the LCI is useful to track early respiratory disease in young people with this condition.

“If an abnormal LCI were proven to correlate with structural lung abnormalities, more rapid decline of lung function or a worse clinical course,” the researchers wrote, “the use of MBW could be considered in the routine respiratory care of patients with SCA (as detection of early lung disease would offer a window of opportunity for therapeutic interventions) and/or as possible endpoint in clinical trials evaluating disease-modifying drugs in this group.”