Table 2.

Effect of age, ethnicity and personal characteristics on marker concentrations. The reference group is women under age 45. Age-related effects on ln(marker levels) are presented in the top half of the table. The bottom half presents the effects of other covariates in terms of percent change of marker levels. The marker value expected for an individual woman can be calculated using this table using instructions in the table footnote. Sample size refers to blood draws not number of women.

Analysis	Covariate	Sample Size	CA125		HE4		ROMA
Age-related effects on ln marker concentrations.*			Coeff.	p-val.	Coeff.	p-val	Effect (log scale)	p-val.
Intercept	Age < 45 (Reference)	370	2.39859	<0.001	2.99346	<0.0005	−4.72542	<0.0005
	45 ≤ age < 55	635	1.92218	0.007	0.25002	0.412	−6.25026	<0.0005
	Age ≥ 55	775	−0.35088	0.365	−0.98948	<0.0005	0.21848	0.583
trends	Age < 45 (Reference)	370	0.00524	0.490	0.00820	0.013	0.01985	0.012
	45 ≤ age < 55	635	−0.04155	0.006	−0.00551	0.398	0.13377	<0.0005
	age > 55	775	−0.00224	0.797	0.01579	<0.0005	0.00730	0.420
Covariate effects on percent change of marker concentrations.			% Change	p-val.	% Change	p-val.	% Change	p-val.
Age Adjust ed Effects	Parous	1186	4.0%	0.355	0.4%	0.867	−0.004	0.935
	Non-White Race	159	6.3%	0.371	3.6%	0.357	0.126	0.122
	Black	18	−26.6%	0.008	−3.3%	0.718	−0.203	0.329
	Asian	42	20.4%	0.112	7.7%	0.474	0.317	0.142
	Other	99	7.5%	0.417	2.9%	0.454	0.094	0.200
	Hispanic	66	19.10%	0.097	1.80%	0.683	0.091	0.388
	Ashkenazi Jewish	325	−7.4%	0.163	0.9%	0.702	−0.011	0.850
	Prior Tubal Ligation	253	0.4%	0.935	−0.3%	0.928	−0.015	0.79
	Current Smoker	58	0.3%	0.977	21.0%	0.007	0.276	0.019
	Current OC use	91	−13.0%	0.100	−1.8%	0.632	−0.115	0.225
	Discontinuous OC	48	−5.4%	0.641	2.4%	0.649	0.04	0.766
	Continuous OC	43	−18.9%	0.041	−5.8%	0.217	−0.265	0.012
	Personal History of BC	584	−3.0%	0.497	3.9%	0.105	0.046	0.335

To approximate the marker value expected for a woman of a specific age, first approximate the baseline LN marker level for the woman’s age as follows. Add the intercept terms (reference group plus the term from the age appropriate category) to the age multiplied by the age-related trend (reference group trend + age appropriate category trend). For example, baseline LN CA 125 level for a woman of age 50 will equal Y=(2.39859+1.92218)+ 50*(0.00524−0.04155) = 2.50, or 12.23 U/ml on the raw scale. To adjust the level on the raw scale for covariates, increase or decrease the calculated raw scale using the approximated effect size for that covariate. For example, a woman of age 50 who is of Black ethnicity will be expected to have CA 125 levels 26.6% lower, or 3.25 U/ml lower.

^*

Coefficients and p values obtained from a linear regression using the formula:

• ln(marker level) ~ intercept + age + I(45 < age < 55) + age * I(45 < age < 55) + I(age > 55) + age * I(age > 55)

Where indicator variables “I(…)” are set to 1 when the condition is met and 0 otherwise. Together, the intercept (e.g. “I(45 < age < 55)”) and trend (e.g. “age * I(45 < age < 55)”) terms allow for independent linear trends to be estimated within each age range.