Table 2.

Drug Use Summary Statistics

	First Author HRR	Other Author HRR	Author HRR for Different Drug	HRR with No Authors
Variables	(1)	(2)	(3)	(4)
Drug utilization rate	0.156	0.097	0.092	0.086
Fraction treated in author’s group	0.534	0.357	0.000	0.000
Number of observations	6,985	29,322	250,330	372,831
Average number of patients per HRR per drug	388	236	254	75
Number of HRR-drug pairs	18	124	986	4958
Number of unique HRRs	11	54	54	252

Regions are defined by the 306 Dartmouth Atlas Hospital Referral Regions (HRRs). For each drug in the sample, regions are partitioned into four groups based on geographic proximity to authors of the pivotal trial, corresponding to the four columns in the table. Statistics are then reported for each column by aggregating over the set of drugs in the sample. Reported statistics reflect drug utilization over the first two years following initial introduction. Data on drug utilization come from Medicare claims, 1998–2008.