Table A1.

Abatacept and Rituximab Use and Expenditures in Medicare Beneficiaries with Rheumatoid Arthritis in 2006

	Abatacept		Rituximab
Identification algorithm	Percent users	Total allowed payments	Percent users	Total allowed payments
(1) All claims with relevant HCPCS code*	0.61%	$22.6 M	0.46%	$38.5 M
(2) Subset of claims in (1) with associated RA diagnosis	0.49%	$19.8 M	0.28%	$16.3 M
(3) Subset of claims in (1) filed by rheumatologists	0.43%	$16.8 M	0.16%	$9.8 M

^*HCPCS code J3590 for abatacept and J9310 for rituximab