Here's troubling news for America's senior citizens. A recent international survey found that adults age 65-plus in the US are sicker than their counterparts in 10 other high-income nations, and they face greater financial challenges regarding their health care. This is despite the universal coverage that Medicare provides.

And it's especially worrisome, given the challenges with Medicare's long-term funding and potential future benefit cuts, which the Republican's new tax cut package could exacerbate.

Here are some key findings from the survey conducted by The Commonwealth Fund:

More than one in three older Americans (36 percent) report having three or more chronic conditions. The next-sickest nation, Canada, is significantly healthier, with just close to one in four Canadians reporting have three or more chronic conditions. The healthiest nation was New Zealand, with only 13 percent of older Kiwis reporting the same.

Nearly one in four older Americans (23 percent) report that in the past year, they hadn't visited a doctor when sick, had skipped a recommended test or treatment, hadn't filled a prescription or had skipped medication doses, all because of the cost. The US is far worse than other nations in this area: 5 percent or fewer respondents reported these cost barriers in France, Norway, Sweden and the UK.

The US is an outlier on out-of-pocket expenses, with 22 percent of American respondents reporting they had spent $2,000 or more for medical care in the past year. In all other countries except Switzerland, fewer than 10 percent of older adults spent that much.

Several reasons are behind these discouraging results, including:

Medicare has much higher deductibles and co-payments compared to health insurance plans in other nations.

Older Americans pay far higher amounts for prescription drugs than seniors in other nations, partly due to Medicare's restriction on negotiating prices with pharmaceutical companies.

Americans have much higher rates of obesity compared to other nations, resulting from lack of exercise and eating too much unhealthy food. For example, the Stanford Center on Longevity Sightlines project reports that only about one in four Americans of all ages eats the recommended five servings of fruits and vegetables each day, just 37 percent of those age 65 to 74 exercise the recommended 150+ minutes each week and the same percentage of that group are obese.

The Commonwealth Fund survey should be a wake-up call for all Americans approaching their retirement years. While Medicare provides a base level of health care, you'll most likely want to supplement Medicare with a Medigap or Medicare Advantage Plan for more complete coverage.

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You'll also want to get serious about taking care of your health by improving your diet, exercising more, bringing your weight to a healthy level, making sure you get enough sleep and stopping smoking, if applicable. You can take encouragement that it's possible by looking at the better health indicators of the other nations surveyed by the Commonwealth Fund.

Given the state of Medicare and other health care plans covering older Americans, you'll need to make smart choices and get all the help you can to manage your health care costs and enjoy your retirement years.