Table 3.

Exposure severity and PRS incremental prediction of total WTC-related PTSD symptoms

	Predictors of PTSD	R2	Δ R2	p
	10 PCs	0.015
Model 1	10 PCs + Exposure	0.021	0.006	0.002
	10 PCs + Exposure + 6 PRSs	0.043	0.022	1.70 × 10−5
Model 2	10 PCs + 6 PRSs	0.037	0.022	1.00 × 10−5
	10 PCs + 6 PRSs + Exposure	0.043	0.006	0.004

Notes: In each hierarchical regression model, 10 ancestry PCs were included first to estimate R². Then, each predictor was added in consecutive blocks, to estimate the change in R² and thus determine whether each added predictor provides novel information about PTSD symptoms, over and above the predictors already included in the model. The predictors were entered in two orders (Model 1: exposure followed by PRSs, Model 2: PRSs followed by exposure).

In 6 PRSs block, PTSD PRS, Re-experiencing-PRS, GAD-PRS, Schizophrenia-PRS, Depression-PRS, and Neuroticism-PRS were entered simultaneously.

p value indicates the significance of ΔR², testing whether including an additional predictor to the model significantly increased the prediction of PTSD symptoms.