Table 1.

Patient and disease characteristics by provider treatment intensity^*

Characteristic	Quartiles of provider treatment intensity				P
	1 (low)	2	3	4 (high)
No. of patients	5198	5154	5177	5184	—
No. of providers	254	204	224	258	—
Mean Medicare expenditures per   patient in 2005 US dollars	2830	3962	4956	7131	—
Patient age at diagnosis (%), y					.32
65–69	17.5	17.9	17.0	18.6
70–74	25.4	25.9	26.7	26.5
75–79	25.6	25.9	25.3	25.3
80–84	17.9	17.4	18.5	17.0
≥85	13.6	12.9	12.5	12.6
Female sex (%)	25.2	24.9	26.2	24.9	.42
Race (%)					<.001
White	92.9	94.4	91.8	92.4
Black	1.8	1.8	2.4	3.5
Other	5.3	3.8	5.8	4.1
Socioeconomic status† (%)					<.001
Low	30.4	31.3	33.7	38.0
Medium	32.3	36.8	33.2	31.0
High	37.3	31.9	33.1	31.0
Comorbidity index (%)					.19
0	45.1	44.0	43.3	42.5
1	29.6	30.1	29.3	30.5
2	14.1	14.7	15.5	14.8
≥3	11.2	11.2	11.9	12.2
Tumor grade‡ (%)					.02
Low	65.1	64.1	63.8	62.6
High	28.5	28.7	28.9	29.1
Unknown	6.4	7.2	7.3	8.3
Tumor stage§ (%)					<.001
Ta	58.4	58.9	54.1	53.0
Tis	6.5	6.5	7.4	7.5
T1	24.3	23.8	26.1	28.6
Ta or T1, not otherwise specified	10.8	10.8	12.4	10.9

^*All P values are two-sided (chi-square test). — = not applicable.

^†Based on summary scores determined according to Diez Roux et al. (26); low (score range  = −12.23 to 1.19), medium (score range  = 1.20 to 5.89), and high (score range = 5.90 to 20.76).

^‡International Classification of Diseases for Oncology, 2nd edition (25).

^§Modified American Joint Commission on Cancer (13).