By Wayne Forrest, staff writer

October 23, 2012 -- A five-year analysis of Medicare beneficiaries with cancer has found greater utilization of PET imaging among white patients with greater income levels in areas of higher Medicare spending.

While the use of PET increased among both black and white cancer patients from 2004 to 2008, black Medicare beneficiaries had lower rates of PET utilization compared to whites, with the difference between the two groups widening during that period.

"Modality-specific differences may reflect more rapid uptake of new technologies among whites and higher income groups compared with blacks and lower income groups," wrote lead author Tracy Onega, PhD, from the department of community and family medicine at Dartmouth Medical School, and colleagues (Journal of the American College of Radiology, September 2012, Vol. 9:9, pp. 635-642).

The results also provide a better understanding of geographical areas and patient populations that could benefit from more PET access, and areas where the modality may be overutilized, according to the authors.

PET on the rise

The use of FDG-PET and PET/CT for patients with cancer approximately quadrupled between 1999 and 2006, previous studies have found. One growth driver during that time was the expansion of national coverage by the U.S. Centers for Medicare and Medicaid Services (CMS) between 1998 and 2005 to reimburse PET imaging for nine different types of cancer.

However, as Onega and colleagues noted, PET use for cancer care "increased unevenly, possibly because of regional healthcare market characteristics or underlying population characteristics."

In the current study, the researchers selected fee-for-service Medicare beneficiaries between the ages of 65 and 99 for the years 2004 through 2008. The study population included an annual average of 116,452 beneficiaries with a median age of 75 years. Approximately 48% of the individuals were women. The racial composition of the study cohort was consistent during each year of the study.

The analysis included both PET-only and PET/CT studies, with PET/CT accounting for nearly 90% of claims. Onega and colleagues also compared PET utilization with the use of CT and MRI among cancer patients to determine geographic and sociodemographic patterns of advanced imaging over the same time period.

PET availability

The number of hospital service areas with PET imaging increased from 28% in 2004 to 34% in 2008, according to the authors. Total Medicare reimbursements per beneficiary for the overall Medicare population in each hospital service area were $8,058, ranging from $6,894 to $9,484, with the greatest variations in outpatient, diagnostic, laboratory, and imaging services.

As for PET utilization, the adjusted rates (imaging days per person, per year) were significantly greater for whites (0.35) compared to blacks (0.31) in 2004. By 2008, the adjusted rates for PET increased to 0.64 for whites, compared with 0.57 for blacks.

Hospital service areas with the highest Medicare spending had significantly higher adjusted PET rates (0.69), when compared with the lowest quartile (0.57). This upward trend and disparity between the two patient groups was similar regarding median household income.

CT and MRI use

Adjusted utilization rates for CT and MRI showed significant increases over time but smaller overall differences by race or income group, the researchers found. In 2004, MRI utilization rates for whites were significantly higher than for blacks, but by 2008, there were no significant differences.

Rates of CT use in black cancer populations were higher in both 2004 and 2008 compared to whites. The adjusted rate for blacks in 2004 was 2.48, compared with 2.37 for whites. In 2008, black patients had an adjusted usage rate for CT of 2.50, compared with 2.32 for white patients.

Rate* by modality for 2004 and 2008
2004 2008
White 0.35 0.64
Black 0.31 0.57
Asian 0.37 0.65
White 0.39 0.43
Black 0.35 0.40
Asian 0.34 0.42
White 2.37 2.32
Black 2.48 2.50
Asian 2.40 2.38
*Imaging days per person, per year

There were no significant differences by race or socioeconomic group for MRI utilization, the authors noted. PET, MRI, and CT use were all greater in hospital service areas with higher spending.

Based on the results, Onega and colleagues concluded that the differences in modality utilization may be due to earlier availability of new technologies among whites and higher income groups compared to blacks and lower income groups.

"It is possible that these patterns represent incomplete diffusion of the new technology and that differences will diminish over time," the authors wrote.

"By furthering our understanding of PET use patterns, we inferred that there are areas and populations that could likely benefit from more PET, as well as areas that may be using this costly modality at a high rate relative to other geographic areas," the group concluded.

Copyright © 2012

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