Table 2:

Linear model to refine the predicted FVC and FEV₁ in OI

		Intercept	Age (year) β1	Age2 (year2) β2	Height2 (cm) β3	Mobility β4	Scoliosis β5	Bisphosphonate β6
Female subjects
OI type
I	FEV1	0.06841	0.08875	−0.00128	0.00005
I	FVC	−0.28034	0.11847	−0.00165	0.00007
III	FEV1	−0.93779	0.05093	−0.00128	0.00014	0.31692
III	FVC	−1.39049	0.10352	−0.00214	0.00017		−0.33132
IV	FEV1	0.28869	0.04383	−0.00066	0.00007			−0.20545
IV	FVC	−0.08906	0.07294	−0.00107	0.00009
Male subjects
OI type
I	FEV1	−0.971	0.2153	−0.00336	0.00005
I	FVC	−0.97289	0.11847	−0.00165	0.00012
III	FEV1	−0.82984	0.05093	−0.00077	0.00014	0.31692
III	FVC	−1.31875	0.10352	−0.00133	0.00017		−0.33132
IV	FEV1	−0.82372	0.16285	−0.00218	0.00007			−0.20545
IV	FVC	−1.10702	0.18679	−0.00251	0.00009

The linear model to evaluate correlation between FVC or FEV1 and other clinical covariates. FVC and FEV1 were calculated using the equation Intercept + β₁ ∗ Age + β₂ ∗ Age² + β₃ ∗ Height² + β₄ ∗ Mobility + β₅ ∗ Scoliosis + β₆ ∗ Bisphosphonate. The values in the table represent β coefficients. Cells without any numbers imply that the covariates were excluded in the stepwise selection used to refine the linear model. For age and height, nominal data were used. For mobility, wheel chair bound was represented as 0 and not wheel chair bound was represented as 1. For scoliosis, 0 represented no scoliosis and 1 represented presence of scoliosis. Similarly, history of ever exposure to bisphosphonates was represented as 0 and 1 represents history of treatment with BPN. R² values for the model predicting variability in FVC and FEV₁ across OI types were 0.70–0.79 and 0.63–0.72, respectively.