Table 3

Multivariable logistic regression for restrictive spirometry pattern (vs normal) in 223 paediatric patients with sickle cell anaemia from Nigeria and the UK

Covariate*Crude OR
(95% CI; p value)		Adjusted OR
(95% CI; p value)
Residency in Nigeria (vs the UK)2.4
(1.2 to 4.7; 0.01)		2.4
(1.1 to 4.9; 0.02)
Age, years1.2
(1.1 to 1.3; <0.001)		1.2
(1.1 to 1.4; <0.001)
zBMI<−22.9
(1.4 to 5.8; 0.003)		2.3
(1.1 to 5.0; 0.03)
Previous acute chest syndrome†1.6
(0.9 to 3.0; 0.13)		1.7
(0.8 to 3.2; 0.12)

  • zBMI values are based on WHO growth charts.25

  • Spirometry z-scores are based on Global Lung Function Initiative 2012 equations for African–Americans.26

  • Restrictive spirometry pattern=FVC<LLN and FEV1/FVC≥LLN.

  • Adjusted R2 of the model=0.12.

  • *Only covariates with a p value<0.2 were retained in the final model. The initial model also included the covariates: ‘male sex’, ‘no hydroxyurea therapy’ and ‘at least three pain crises in the last 12 months’ (saturated models are presented in online supplementary data).

  • †Fever and/or respiratory symptoms, plus a new pulmonary infiltrate on a chest X-ray.22

  • LLN, lower limit of normal; zBMI, z-score body mass index.