Table 4 Simple linear regression models of total HRCT score and linear/triangular opacities score with respect to lung function variables (n = 74)

	Linear/triangular opacities			Total HRCT score
	β	R²	p Value	β	R²	p Value
FEV₁	−0.028	0.055	0.044	−0.090	0.169	<0.001
FEF_25–50	−0.027	0.128	0.002	−0.427	0.183	<0.001
FEF₅₀	−0.030	0.173	<0.001	−0.063	0.236	<0.001
RV/TLC*	0.072	0.075	0.021	0.149	0.101	<0.001

Variables of lung function are explanatory variables whereas linear/triangular opacities (0–6) and total HRCT score (0–50) are response variables. Except for the ratio RV/TLC, lung function variables are expressed as percentages of predicted values. Briefly, the β values describe the effect from one unit change in the explanatory variable on the response variable.
*Four preterm individuals were unable to enter the plethysmograph, implying n = 70 for RV/TLC.
FEV₁, forced expiratory volume in 1 s; FEF_25–50, FEF₅₀, forced expiratory flow at 25–50% and 50% of forced vital capacity; RV, residual volume; TLC, total lung capacity.