AMD Treatment Selection Influenced by Cost, Demographics

Emily Gower, PhD

The odds of receiving ranibizumab (Lucentis) versus bevacizumab (Avastin) for wet age-related macular degeneration (wAMD) therapy post-diagnosis varies geographically and demographically, but that overall there has been a decrease in the use of ranibizumab as an initial wAMD therapy, according to study results.

The study, which used Medicare beneficiary data from 2006 to 2009, also posited several hypotheses for the difference in treatment selection. Pressure to reduce Medicare spending by selecting lower cost treatment options for Medicare beneficiaries, a concern with personal liability based on FDA approval status of the Genentech/Roche treatments and drug reimbursement rates may "create an unconscious bias" among physicians regarding treatment selection.

The 3-year study, lead Emily W Gower, PhD, with the University of North Carolina Gillings School of Global Public Health, used diagnosis-codes, as well as claim- and beneficiary-level data on treatment post- initial diagnosis of wAMD for a 100% (n = 195,812) sample of wAMD Medicare beneficiaries in order to determine demographic and geographic data on initial treatment selection.

The motivation behind identifying treatment patterns is important "because it can shed light on potential access to care issues for both agents," per Gower and colleagues. The study cohort included 100% of Medicare Parts A and B beneficiaries over age 66 with wAMD index claims on or after July 1, 2006.

Gower and colleagues charted geographic trends via each beneficiary’s "zip code of residence from the year of the index claim to a Hospital Referral Region (HRR) and to 1 of the 9 major geographic divisions as designated by the US Census Bureau."

Data showed that the proportion of Medicare beneficiaries receiving either agent for wAMD treatment "varied significantly across HRRs within a census division, ranging from 0.9% in Owensboro, KY and Grand Junction, CO to 84.6% in Victoria, TX." The highest average proportion receiving ranibizumab were those in New England at 48.4%, and the lowest median proportion in the Mountain region at 12.3%.

Overall, data showed that beneficiaries' odds of receiving ranibizumab post- initial diagnosis decreased by 61% between 2006 and 2009, but increased with advancing age and according to racial demographics. Gower writes that "Among those who were classified as black, the odds of receiving ranibizumab was reduced by 45% (P <.0001) relative to non-blacks."

Income data showed that those Medicare beneficiaries receiving Medicaid "had 33% (P <.001) reduced odds of receiving ranibizumab" compared to beneficiaries in higher-income urban areas. Additionally, those beneficiaries with a pre-existing diagnosis of the cerebrovascular disease had an increased 8% (P <.001) likelihood of receiving ranibizumab.

In their discussion of data, the investigators pointed to several factors that might explain the geographic, demographic, and income-based variations in treatment. Among those factors are reimbursement factors associated with Medicare.

Gower wrote that "in areas with a lower patient volume, physicians may not be willing to take the risk to stockpile the more expensive medication." Gowen and colleagues pointed out that ranibizumab costs "up to 40 times more per injection" in comparison to bevacizumab, and ability to pay may influence ophthalmologists' treatment decisions.

According to the study, comparative clinical trials have proven similar efficacy and initial safety for both treatments. As of the study's date of publication bevacizumab does not have approval from the US Food and Drug Administration (FDA) and there is a lack of data on "systemic and ocular side effects" for bevacizumab which, unlike ranibizumab, "requires compounding, which may increase the risk of blinding eye infections."

Despite the lack of what Gower and associates call "well-powered" clinical trials on safety, the use of bevacizumab is on the rise, particularly for lower-income beneficiaries. This suggests that cost may be 1 of the biggest factors influencing treatment agent selection. Gower and colleagues stated that further research should concentrate on what motivates the preference for 1 treatment option over another, whether that decision connotes "differential access" to therapies, and whether that choice has any impact on patient treatment and outcomes.

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