Table 4.

Multivariate modeling of relationship of mCRC patient characteristics to receipt of KRAS testing as part of clinical care.

Treatment Status Characteristics						Demographic Characteristics
Characteristic	Value	N	% Tested	OR (95% CI)	p-value2	Characteristic	Value	N	% Tested	OR (95% CI)	p-value
Chemotherapy Regimens	0	184	7	0.02 (0.003, 0.10)	<.0001	Race	White	826	37	--	0.8221
	1	174	16	0.08 (0.06, 0.10)			Asian	94	45	0.6 (0.3, 1.2)
	2	174	43	0.43 (0.33, 0.57)			Black	127	29	0.8 (0.4, 1.7)
	3	170	69	1.05 (0.86, 1.30)			Pacific Is.	24	54	1.0 (0.3, 3.0)
	4	129	62	0.41 (0.36, 0.44)			Am. Indian	6	33	0.8 (0.1, 7.9)
	≥5	357	74	--			Other	41	24	1.6 (0.4, 2.8)
							Unknown	70	21	1.0 (0.4, 2.5)
Surgery1	No	456	23	0.63 (0.40, 0.91)	0.0187	Ethnicity	Not Hispanic	911	35	--	0.5002
	Yes	732	44	--			Hispanic	72	38	0.7 (0.3, 1.4)
Referral to Med. Oncology	No	171	3	0.77 (0.21, 2.5)	0.6569	Gender	Male	601	37	--	0.5899
	Yes	1017	40	--			Female	586	35	0.8 (0.6, 1.2)
Any EGFR inhibitor	No	936	28	--	0.0014	Household Income	< $40K	316	30	0.8 (0.5, 1.4)	0.4753
	Yes	252	65	2.0 (1.3, 3.1)			$40K - $59K	405	35	--
Health Status Characteristics							$60K - $79K	231	39	1.3 (1.1, 1.4)
Characteristic	Value	N	% Tested	OR (95% CI)	p-value		≥ $80K	170	37	1.2 (1.1, 1.5)
Age at diagnosis, years	< 50	138	46	1.4 (0.8, 3.0)	0.0034	% High School Education	< 50%	16	25	0.7 (0.1, 3.3)	0.9924
	50-59	234	53	2.4 (2.3, 3.0)			50-69%	99	36	1.4 (1.0, 1.8)
	60-69	292	49	1.7 (1.3, 2.5)			70-89%	580	34	--
	70-79	303	24	--			≥ 90%	426	39	1.2 (1.0, 1.4)
	≥ 80	221	10	0.4 (0.3, 0.7)
Charlson Co-morbidity Index	0	647	45	--	0.0316	Year of Metastatic Diagnosis	2006	261	19	0.06 (0.02, 0.1)	<.0001
	1	346	49	0.5 (0.1, 1.4)			2007	351	35	0.2 (0.2, 0.5)
	2	134	40	0.3 (0.1, 0.8)			2008	373	48	--
	3	30	41	0.5 (0.2, 1.7)			2009	203	46	0.9 (0.7, 1.1)
	4	21	38	0.6 (0.2, 2.0)		Medicare	No	855	32	--	0.1883
	≥ 5	10	20	0.3 (0.1, 0.8)			Yes	333	45	1.8 (0.9, 2.2)
BMI Category	<20	78	22	0.9 (0.4, 2.0)	0.7945	Organization	A	101	44	0.7 (0.4, 1.1)	0.0220
	20-24	254	35	0.9 (0.8, 1.0)			B	426	40	--
	25-29	304	40	--			C	149	38	0.6 (0.5, 0.8)
	≥ 30	264	43	1.2 (1.1, 1.3)			D	193	34	0.6 (0.4, 0.8)
Survival Interval, years (if deceased)	0.5	466	6	--	0.0010		E	124	30	0.3 (0.2, 0.4)
	0.5–1	130	28	1.9 (0.8, 4.3)			F	62	29	0.6 (0.4, 0.8)
	1 – 2	204	36	2.9 (1.4, 6.3)			G	133	28	1.0 (0.6, 1.3)
	≥ 2	388	62	5.1 (2.3, 11.4)		Family History of Cancer	No	349	37	0.9 (0.6, 1.3)	0.5208
Cancer Stage	III	266	45	1.7 (1.1, 2.5)	0.0078		Yes	510	42	--
	IV	922	34	--			Unknown	329	26	0.7 (0.4, 0.9)

OR=odds ratio. CI= confidence interval. The largest group in each category is used as the basis of the OR.

¹Colectomy or hemicolectomy

²All reported Wald chi-square p-values and ORs are from a logistic regression model including all factors in Table 4, and a binary variable indicating presence or absence of KRAS testing as the response variable. Since the reported percent tested is based on the raw, unadjusted counts, there can be apparent discrepancies between the percent tested and the reported adjusted ORs.