Estimating and Interpreting Effects from Nonlinear Exposure-Response Curves in Occupational Cohorts Using Truncated Power Basis Expansions and Penalized Splines

Table 1

Estimated hazard ratios (HR) and 95% pointwise confidence intervals from two Cox proportional hazard model fits.

Exposure; value	Penalized spline function AICc as in Figure 6	Linear spline function with knots at quartiles of case; exposures as in Figure 5(a)	True HR
2.0	1.3 (1.2, 1.5)	1.3 (1.1, 1.6)	1.5
3.0	1.5 (1.3, 1.8)	1.5 (1.1, 2.1)	1.7
4.0	1.8 (1.4, 2.2)	1.8 (1.3, 2.3)	2.0
5.0	2.0 (1.6, 2.5)	2.1 (1.6, 2.7)	2.3
7.0	2.5 (2.0, 3.1)	2.5 (2.0, 3.3)	2.9
9.0	2.9 (2.3, 3.6)	2.9 (2.2, 3.8)	3.5
19.3	3.7 (2.1, 6.3)	4.1 (2.5, 6.5)	4.0
21.1	3.5 (1.7, 7.3)	4.3 (2.5, 7.5)	3.5
24.0	3.3 (1.1, 9.9)	4.7 (2.4, 9.2)	2.6