Using complete Medicare Part A and B data for Texas, the researchers selected PCPs whose patient panels included at least 20 men 75 years or older without a prior diagnosis of prostate cancer. Primary care physicians were identified as generalist physicians who saw a man on 3 or more occasions in 2009. PSA screening rates for 2010 were estimated. The sample included 1,963 PCPs and 61,351 patients. Overall, 41.1 percent of the men received PSA screening and 28.8 percent received PSA screening ordered by their PCPs. Both rates declined with patient age.

The authors found high variability among PCPs in PSA screening, with a 10-fold difference in rates between the highest and lowest deciles (divided into ten groups) of PCPs. In addition, which PCP a man saw explained approximately 7 times more of the variance in PSA screening than did the measurable patient characteristics.

"The high variability among PCPs in ordering PSA screening for older men requires additional study to understand its causes. It has been suggested that overtesting rates be included as quality measures of PCPs. Medicare data can be used to generate such measures."