Table 2.

Comparison Between Medical Chart Reviews and Medicare Claims on Chemotherapy

		Agreement Between Medical Chart Reviews and Medicare Claims for Chemotherapy
Characteristics	No. Patients	Kappa (95% Confidence Interval)	Observed Agreement (%)	P Value for Homogeneity*
All patients	1228	0.69 (0.63–0.76)	94.4	—
Source of medical charts for documenting chemotherapy
Oncologist's office
Yes	308	0.78 (0.67–0.89)	95.1	0.624
No	920	0.66 (0.57–0.74)	94.1
Radiation department
Yes	212	0.86 (0.74–0.98)	97.6	0.135
No	1016	0.66 (0.59–0.74)	93.7
Other physician's office
Yes	251	0.52 (0.31–0.73)	93.6	0.020
No	977	0.72 (0.65–0.79)	94.6
Tumor stage
Early stage (I + II)	961	0.66 (0.57–0.76)	95.6	0.058
Late stage (III + IV)	176	0.72 (0.61–0.83)	88.1
Unstaged (unknown)	91	0.47 (0.11–0.83)	93.4
Hormone therapy
Yes	421	0.80 (0.70–0.90)	96.4	0.479
No	807	0.64 (0.56–0.73)	93.3
Year of diagnosis
1993–1996	513	0.66 (0.52–0.80)	96.3	0.178
1997–1999	715	0.70 (0.62–0.78)	93.0

^*P value of the Breslow-Day test for homogeneity across the strata.