Table 9.

Variance inflation factors

Outcome	k	FiO₂ VIF	Duration VIF	Frequency VIF	Weeks VIF	Max VIF	Assessment
BMI	7	1.25	3.82	2.92	6.45	6.45	Moderate concern

Variance inflation factors (VIF) for multivariate meta-regression model predicting BMI. VIF < 5 indicates acceptable collinearity; 5–10 indicates moderate concern requiring cautious interpretation; >10 indicates severe multicollinearity precluding reliable multivariate estimation. Only BMI had sufficient studies (k ≥ 5) for VIF calculation.