Public anger over the cost of drugs has burned hot for a year, writes The New York Times, coursing through social media, popping up on the presidential campaign, and erupting in a series of congressional hearings, including one last week over the rising price of the allergy treatment EpiPen. But one set of voices has been oddly muted — the nation’s biggest patient advocacy groups. The groups wield multimillion-dollar budgets and influence on Capitol Hill, but they have been largely absent in the public debate over pricing. But critics say that by avoiding the debate over cost, they are failing in their patient-advocacy duties. “It is a conflict of interest, because the interests of the pharmaceutical industry, from whom they are getting support, may be different from the interests of the patients,” said Dr. Michael Carome, the director of the Health Research Group at Public Citizen, a consumer advocacy group.