Whether states, hospitals and smaller practices that spend more money on health care provide better treatment is still an open question, according to a new review of past studies.

"This is really one of the central issues we're grappling with today in health care," said Peter Hussey from the RAND Corporation in Arlington, Virginia.

The topic is especially pressing because although the United States spends more of its budget on health care than any other wealthy nation - and is spending more each year - the World Health Organization ranks its health system 37th.

According to the Kaiser Family Foundation, the U.S. spent nearly $2.6 trillion on health in 2010 - equal to just under 18 percent of the country's gross domestic product (GDP).

Hussey and his colleagues analyzed results from 61 studies that compared health care spending with outcomes on both small, hospital-wide scales and broader state-wide levels.

Some of those studies looked at whether hospitals that spent more money per patient had fewer in-hospital deaths, or if their doctors and nurses better followed guidelines. Others compared states' Medicare spending with how well their older residents were treated for a range of conditions.

"The bottom line was that no matter how you drill down into the results, at every level the results are just all over the map," Hussey told Reuters Health.

"It's totally unclear what the real relationship is."

Twenty-one of the 61 studies showed higher spending was tied to better outcomes for patients, such as fewer deaths. However, 18 studies found a link between more spending and worse outcomes, and 22 showed no difference or an unclear association based on spending, according to findings published in the Annals of Internal Medicine.

For example, in one 2010 study the one-quarter of hospitals with the highest spending per patient had better quality scores than the lowest-spending hospitals when it came to treating people with heart failure, but were worse at treating pneumonia patients.

Many of the studies compared certain types of spending with potentially unrelated outcomes, according to Hussey. Others didn't take into account how sick patients were initially when looking at how they fared in different situations.

Hussey said there are likely some places in the health care system where spending can be cut without reducing quality - but so far, it's unclear what those areas are.

Getting doctors involved

Although health spending is a hot-button issue, doctors are typically focused on getting their patients better and not on how much that might cost, according to Dr. Alyna Chien, from Harvard Medical School in Boston.

"Putting the two together - meaning you want to improve quality or maintain quality while decreasing costs - is even more complicated," said Chien, who co-wrote an editorial accompanying the new study.

One hurdle is that most doctors don't have any idea what the drugs they prescribe or the tests they order actually cost - for the patient or the health care system in general, she told Reuters Health.

"You need physicians to know some of that information because they also have to talk to the patient about what they care about," Chien said.

"Sometimes patients just think more (treatment) is better," without knowing that a cheaper option might be just as effective.

The researchers both said further studies are needed to help address overspending in the U.S. Researchers should look for links between specific types of spending and outcomes that are likely to be directly related, according to Hussey.

And cost analyses should be included in studies of new treatment options, Chien said.

"Having that price tag information would help people know which intervention is easier to implement or sustain," she said.