TABLE 1

Demographics and test results of study population

Subjects n154
Demographics
 Age years12.6±3.3 (6–18)
 Male sex n (%)76 (49%)
 Hb genotype n (%)
  HbSS106 (69%)
  HbSC34 (22%)
  HbSB+thal9 (6%)
  HbSBothal4 (3%)
  HbSE1 (1%)
 History of ACS n (%)56 (36%)
Pulmonary function testing
 FVC % predicted86.7±14.0 (53–127)
 FEV1 % predicted84.8±15.0 (48–118)
 FEV1/FVC %86.1±6.1 (64–98)
 FEF25–75 % predicted84.4±29.9 (31–261)
 12% change in FEV1 or FVC n (%)20 (13%)
 30% change in FEF25–75 n (%)46 (30%)
ISAAC questionnaires#
 Physician diagnosis of asthma n (%)24 (22%)
 History of ever having wheezed n (%)42 (39%)
 History of recent wheezing n (%)21 (19%)
Airway nitric oxide measurements
 Fractional exhaled nitric oxide ppb17.9±15.9 (2–102)
 Nasal nitric oxide ppb890±387 (16–3146)
Rate of decline in FEV1/FVC+
 History of recent wheezing % (95% CI)0.90 (0.61–1.19)
 No history of recent wheezing % (95% CI)0.33 (0.22–0.44)

Data are presented as population mean±sd, unless otherwise stated. Values in parentheses represent minimum/maximum ranges, unless otherwise stated. Spirometric values were derived from the Hankinson equations [6]. Hb: haemoglobin; ACS: acute chest syndrome; FVC: forced vital capacity; FEV1: forced expiratory volume in 1 s; FEF25–75: forced expiratory flow at 25–75% of FVC; ISAAC: International Study of Asthma and Allergies in Childhood. #: n=108; : n=144; +: n=97.