Leaving out the procedure mix variables has virtually no effect on the BCSRT estimates, but reduces the BCSO fee coefficients by about one-third.
0 times more likely than white beneficiaries to receive BOSO relative to MST or BCSRT, but only slightly less likely to receive BCSRT relative to MST.
We addressed many of the potential limitations and sources of bias in the earlier analysis by using data for individual women with confirmed diagnoses of early-stage breast cancer, by isolating the effect of variations in pure fees, by distinguishing between BCSRT and BCSO, and by controlling directly for the effects of prior health condition and disease stage.
This may be due to both the relatively small number of women receiving BGSO, only 190 cases, and a real difference in the effect of Medicare fees on the choice between a less aggressive treatment, BOSO, and more aggressive treatments of BCSRT and MST.
If this inference is valid, then our earlier study, which could not distinguish BCSO from BCSRT, may have understated the effects of Medicare fees by combining BCSO and BCSRT cases.
Women were more likely to receive BCSRT in areas where the high-fee BCS procedure (code 19 162- removal of breast lesion and axillary nodes) was a relatively high proportion of Medicare BCS procedures.
As suggested above, our finding of a significant fee effect in the choice between BCSRT and MST may imply that physicians feel greater latitude in responding to financial incentives because BCSRT and MST have comparable survival outcomes in women with localized disease, although there is growing evidence that some quality of life outcomes are better among women treated by BCS compared to those receiving MST (Ganz et al.