Clinical and laboratory comparisons
Four from the control group declined a blood draw (or had inadequate sample for processing) and were presumed to be either carriers or have HBAA genotype given no stigmata of SCD (Table 2). SCD subjects demonstrated a significantly lower hemoglobin concentration, higher white blood cell count and lower daytime oxygen saturation level.
A comparison of pulmonary function data is shown in table 3 . TLC and FEV1 were significantly higher in the healthy controls compared to those with SCD. There was no significant difference in LCI among the comparison groups. In our patient cohort, we saw no changes in LCI with increasing age (Figure 2 )
Amongst the subjects with SCD, a normal pattern of lung function was noted in 31 patients (91%), an obstructive pattern in 3 patients (9%), and a mixed obstructive/restrictive pattern in only 1 patient (3%). Four (12%) of the SCD participants demonstrated bronchodilator responsiveness. However, nineteen (56%) had a physician diagnosis of asthma. There was no statistically significant difference in pulmonary function indices between patients with SCD (n=18) and healthy controls (n=17) ages 6-12 years. However, a comparison between participants with SCD and healthy controls ages 13-18 years revealed that TLC and FEV1 z-score values were significantly higher in the healthy control group (0.86 +/-1.25 vs -0.22 +/-1.37; P=0.02) and (0.28 +/-1.11 vs -0.53 +/-1.01; p=0.03).
SCD subjects of all ages without a history of asthma had significantly higher TLC z-score values vs those with asthma (0.74 +/-1.21 vs -0.32 +/- 1.11 with asthma; p=0.002) but there were no differences in LCI (7.31 +/-0.65-without asthma vs 7.44 +/-0.83 with asthma; p= 0.5085).
A history of ACS was associated with a lower TLC z-score (-0.74 +/- 0.96 vs 0.41 +/- 1.30, p=0.015) and FEV1 (-0.76 +/- 0.54, 0.08 +/- 1.25; P=0.013). However, a history of ACS was not associated with higher LCI ((7.25 (0.48) for history of ACS vs 7.47 (0.78); p=0.411)). A history of asthma or response to bronchodilator was not significantly associated with LCI