Table 4.

Multivariate Cox proportional hazards models for lung cancer risk associated with NCN characteristics for different time periods.

	Time Period	0–23 Months	24–59 Months	60–84 Months
Spatial Level	Presence/Absence of NCNs 1	HR (95% CI)	HR (95% CI)	HR (95% CI)
Person	≥1 NCN (vs. no NCNs)	9.8 (7.8 –12.2)	2.0 (1.6–2.5)	1.6 (1.2–2.2)
Lung	≥1 NCN (vs. no NCNs)	17.1 (13.7– 21.3)	2.9 (2.3–3.6)	2.3 (1.6–3.2)
	NCN in other lung (versus none)	0.7 (0.6–0.9)	0.9 (0.7–1.2)	1.0 (0.8–1.2)
Lobe	≥1 NCN (vs no NCNs)	40.4 (33–50)	5.2 (4.1–6.6)	3.0 (2.0–4.5)
	NCN in another lobe (versus none)	0.6 (0.5–0.8)	1.0 (0.8–1.3)	1.3 (0.9–1.9)
Lobe	NCN Characteristics 2
	≥1 10+ mm NCN (versus only 4–9 mm NCNs)	12.8 (9.5–17.2)	4.7 (2.9–7.5)	N.S.
	≥1 NCN w/ Spiculated or Poorly Defined Margins (versus only NCNs with smooth margins)	4.1 (3.0–5.5)	2.3 (1.5–3.5)	N.S.
	≥1 Persistent NCN (versus non-persistent NCNs)	N/A 3	4.8 (2.8–8.3)	N.S.
	All NCNs Soft Tissue Attenuation	Ref	Ref	Ref
	≥1 NCN w/ Ground Glass Attenuation	0.3 (0.2–0.4)	N.S.	3.1 (1.4–6.6)
	≥1 NCN w/ Mixed Attenuation	N.S.	N.S.	N.S.

¹Model is for all lobes. Other factors in model were age, sex, smoking status, pack years, and COPD status.

²Model is for only those lobes with at least one NCN. Forward step-wise approach was employed for variable selection for NCN characteristics; N.S. denotes that the factor was not selected for the final model in the step-wise process. The characteristic of multiple NCNs in a lobe was not selected for any time period. Other factors in model were age, sex, smoking status, pack years, and COPD status.

³Not applicable because lung cancer assessments begins immediately with no lag.