Table 5. Odds Ratios for Risk Factors for the Presence of Nodules on Initial CT Scan^*.

	Parameter	Category	OR	95% OR Limit-Lower	95% ORLimit-Upper	p-value
All participants	Gender (female vs. male)	SSN	0.50	0.31	0.80	0.004
	Age (older vs. younger)	Mixed	1.06	1.04	1.09	<.0001
	Emphysema (present vs. absent)	SN	1.50	1.10	2.03	0.01
	Emphysema (present vs. absent)	SSN	1.68	1.05	2.70	0.03
Men	Age (older vs. younger)	SN	1.03	1.01	1.05	0.011
	Age (older vs. younger)	Mixed	1.07	1.03	1.10	<.0001
	Emphysema (present vs. absent)	SN	1.97	1.31	2.95	0.001
Women	Age (older vs. younger)	Mixed	1.06	1.03	1.09	0.0002

^*Stepwise logistic regression, with OR calculated by gender, presence of emphysema or current age versus 1 year increase in age. For example: OR shows increased age to be a significant risk factor for nodules versus the reference parameter, younger age. Only significant predictors for each category are included.

Abbreviations: SN = solid nodule, SSN = sub-solid nodule.