WASHINGTON -- Millions of seniors enrolled in some of the most popular Medicare prescription drug plans face double-digit premium hikes next year if they don't shop for a better deal, says a private firm that analyzes the highly competitive market.

Seven of the top 10 prescription plans are raising their premiums by 11 percent to 23 percent, according to a report this week by Avalere Health.

It's a reality check on a stream of upbeat Medicare announcements from the Obama administration, all against the backdrop of a hard-fought election. In August, officials had announced that the average premium for basic prescription drug coverage will stay the same in 2013, at $30 a month.

The administration's number is accurate as an overall indicator for the entire market, but not very helpful to consumers individually since it doesn't reflect price swings in the real world.

"The average senior is going to benefit by carefully scrutinizing their situation, because every year the market changes," Avalere President Dan Mendelson said. Avalere crunched the numbers based on bid documents that the plans submitted to Medicare.

The report found premium increases for all top 10 prescription drug plans, known as PDPs. However, the most popular plan – AARP MedicareRx Preferred – is only going up 57 cents per month nationally, to $40.42 from the current $39.85.

President Barack Obama's health care law does not appear to be the cause of the increases. Indeed, the law is improving the prescription benefit by gradually closing a coverage gap called the "doughnut hole," which catches people with high drug costs. Instead, the price hikes appear to be driven by market dynamics, and some insurers are introducing new low-premium options to gain a competitive advantage on plans that are raising their prices.

The seven plans with double-digit premium increases were: the Humana Walmart-Preferred Rx Plan (23 percent); First Health Part D Premier (18 percent); First Health Part D Value Plus (17 percent); Cigna Medicare Rx Plan One (15 percent); Express Scripts Medicare-Value (13 percent); the HealthSpring Prescription Drug Plan (12 percent); and Humana Enhanced (11 percent).

Another two plans in the top 10 also had single-digit increases. They were the SilverScript Basic (8 percent) and WellCare Classic (3 percent).

On the plus side for consumers, a major new low-cost plan entered the market. Premiums for the AARP MedicareRx Saver Plus Plan will average $15 a month nationally, although it won't be available everywhere. That's $3.50 less than the current low-cost leader, the Humana Walmart plan, whose premiums are rising to $18.50.

The new AARP plan is run by UnitedHealth Group Inc., the nation's largest health insurance company. United pays AARP for the right to use its name on a range of Medicare insurance products, a successful business strategy that has proven lucrative for both partners. When Humana and Walmart teamed up to offer their low-cost plan in 2011, United felt the competition.

"There is a real focus on the premium in this market," Mendelson said. "If a plan fields an offering with a low premium, it knows it can capture a significant number of customers."

Medicare spokesman Brian Cook did not dispute the Avalere estimates. "We continue to encourage seniors to shop around and find the plan that works best for them," he said.

Medicare's open enrollment season starts Oct. 15, and beneficiaries have a wide variety of choices of taxpayer-subsidized private prescription plans. Seniors and family members can use the online Medicare Plan Finder to input individual prescription lists and find plans in their area that cover them.

About 90 percent of Medicare's nearly 50 million beneficiaries have some form of drug coverage, with more than 17 million enrolled in private plans through the prescription drug program. Of those, 14 million are in the top 10 plans.

The Avalare numbers, released Monday, do have one silver lining for the Obama administration. When the projections are tweaked to account for seniors switching to lower-cost coverage, premiums for 2013 are likely to remain steady.

Separately, the administration recently announced that average premiums for Medicare Advantage insurance plans will barely inch up next year on average, while enrollment in the private medical plans will continue to rise. Many Medicare Advantage plans also combine prescription drug coverage in one package deal.

But the biggest premium announcement is yet to come.

Virtually all seniors pay the Part B premium for outpatient care, including those with traditional Medicare as well as those in private plans. Currently $99.90 a month, the Part B premium is expected to rise by about $7 for 2013, according to the government's own projections.

___

Online:

Loading Slideshow...
  • $44 Million Hospital Visit

    Unemployed doorman Alexis Rodriguez <a href="http://www.huffingtonpost.com/2012/01/16/bronx-lebanon-hospital-center_n_1208921.html" target="_hplink">received a bill for $44.8 million from Bronx-Lebanon Hospital Center</a>. Thankfully, the outrageous bill was the result of a billing company error, in which they mistakenly put the invoice number in the space where the invoice amount should go.

  • $201,000 Cell Phone Bill

    Celina Aarons of South Florida received a <a href="http://www.huffingtonpost.com/2011/10/18/celina-aarons-201000-cell-phone-bill_n_1017723.html" target="_hplink">43-page cell phone bill </a>adding up to $201,000. The bill was no mistake. Aarons, who also has her two deaf-mute brothers on her plan, forgot to change their data to international after the pair spent two weeks in Canada, accruing up to $2,000 in data charges.

  • Paying For Crime

    After Loretta Robinson's son was killed by a drunk driver, she was <a href="http://www.huffingtonpost.com/2012/06/24/loretta-robinson-mother-billed-cleanup-son-killed-by-undocumented-drunk-driver_n_1622301.html" target="_hplink">billed for various charges, including a $50 charge to clean up her son's blood</a> from the road along with charges to tow and store the suspect's vehicle after the incident.

  • Auto Bill-Pay Nightmare

    Alina Simone thought she didn't have to worry about her cell phone bill as she had set up auto bill-pay. However, when she finally checked her statement, she discovered that she was <a href="http://www.huffingtonpost.com/2012/03/01/sprint-cell-bill-autopay_n_1310312.html" target="_hplink">being charged per text message</a>, racking up more than $700 in fees despite the fact that her plan entitled her to 1,000 free texts per month.

  • $37,000 In Sweets

    A Middletown, Ohio teen got caught <a href="http://www.huffingtonpost.com/2009/02/10/teen-charged-with-billing_n_165531.html" target="_hplink">charging over $37,000 worth of candy</a> to his high school's purchasing number. After the company, The Goodies Factory, became suspicious, authorities arrested the 18-year-old at his home when he went to receive the empty package.

  • Debtors' Prison

    Breast cancer survivor Lisa Lindsay was <a href="http://www.huffingtonpost.com/2012/04/23/lisa-lindsay-breast-cancer-survivor-debtors-jail_n_1446391.html" target="_hplink">arrested after she refused to pay a $280 medical bill</a>, which was sent to her by accident.

  • Billed After Body Violation

    A New Mexico woman was <a href="http://www.huffingtonpost.com/2011/09/07/woman-sent-1000-bill-for-_n_952135.html" target="_hplink">billed for a mandatory body cavity search</a> after being accused of concealing heroin. The search turned up nothing and the woman was not arrested or charged, however she received a bill for $1,122 from the hospital that performed the search.

  • $16 Million Cable Bill

    An Ohio man was <a href="http://www.huffingtonpost.com/2011/04/04/time-warner-cable-bill_n_844506.html" target="_hplink">charged over $16,000,000 by Time Warner Cable</a> after he accrued some odd charges for watching the March Madness tournament. The bill was eventually blamed on human error.