WASHINGTON — Preferred pharmacies for Medicare Part D drug plans are more accessible in suburbs and rural areas than in cities, a study by the Centers for Medicare and Medicaid Services (CMS) has found.

“While we appreciate the importance of providing lower costs to beneficiaries, these findings reinforce CMS’ concern that plans are offering access to pharmacies with lower cost-sharing in a way that may be misleading to beneficiaries, in violation of CMS requirements,” the study says. “In addition to providing meaningful levels of access, plan sponsors must also provide a uniform set of benefits throughout the plan service area.”

Virtually all full pharmacy networks provide convenient access in all areas, researchers found. But 79% of preferred pharmacy groupings in cities offer easy access, compared to 94% in suburbs and 88% in less densely populated regions.

The agency said it would hold discussions with “outliers” and scrutinize plans providing low levels of access. It promised to continue monitoring complaints and access levels and to consider future policy options.

“While minimum access standards have applied to the basic pharmacy networks of drug plans since the inception of the Part D program, the relatively recent and far more limited ‘preferred’ networks have been the proverbial ‘Wild West’ with no consumer safeguards,” said B. Douglas Hoey, chief executive officer of the National Community Pharmacists Association (NCPA). “Many patients are confused and don’t understand terminology like ‘preferred’ versus ‘network’ pharmacies and have long-standing ties to their local pharmacists, whose pharmacy may be excluded.”

The NCPA has long raised concerns over inadequate access to preferred pharmacies in Part D plans, particularly in underserved areas. Independent pharmacies are often excluded from preferred groupings, even when offering to meet plans’ terms and conditions, said Hoey.

He pointed to legislative action last year in support of patient choice and pharmacy participation in plans.

“Bipartisan ‘any willing pharmacy’ legislation (H.R. 4577) was introduced and garnered 80 cosponsors,” Hoey noted. “Leading consumer and health advocates endorsed the bill as well. Voters expressed their overwhelming support for allowing patients to use a pharmacy that will accept their drug plan’s terms and conditions. An economic analysis demonstrated how, under H.R. 4577, Medicare costs could be the same or even reduced through increased pharmacy choice and competition to drive costs lower.

“However, more must be accomplished. NCPA will continue to work with Congress, CMS and others until Medicare beneficiaries are allowed to go to any pharmacy willing to accept the pricing and terms of being a ‘preferred’ pharmacy.”

But the Pharmaceutical Care Management Association (PCMA), which represents pharmacy benefit managers, warned against overhauling the Part D program.

“When Congress returns, CMS may want to brief it before changing Medicare Part D’s popular low-premium plans,” said PCMA president and CEO Mark Merritt. Congress was assured in 2014 “that CMS would pursue no ‘controversial’ changes,” he said.

PCMA cited a Hart Research Associates survey that found that nine out of 10 seniors from urban, suburban, small town and rural areas have convenient access to discounted pharmacies under Part D.

The organization also cited a letter from the Federal Trade Commission to CMS cautioning that “the proposed any willing pharmacy provisions threaten the effectiveness of selective contracting with pharmacies as a tool for lowering costs. Requiring prescription drug plans to contract with any willing pharmacy would reduce the ability of plans to obtain price discounts based on the prospect of increased patient volume and thus impair the ability of prescription drug plans to negotiate the best prices with pharmacies.”

Most national Part D pharmacy networks include virtually all drug stores, some 64,000 nationwide, PCMA ­noted.