Healthcare spending grew faster in 2014 than the previous five years partly because of a strengthening economy and coverage expansions through Obamacare.

New estimates released Tuesday show that estimated healthcare spending grew by 5.5 percent in 2014, well above the historic low of 4 percent from 2008 to 2013.

The study also projected a 5.8 percent rate of long-term growth in healthcare spending from 2014 to 2024. That is an increase of about one percentage point from last year's analysis, according to the annual study from the Office of the Actuary at the Centers for Medicare and Medicaid Services.

In addition to 2014's estimates, the agency projects that spending growth will slow slightly to 5.3 percent in 2015 and maintain that rate from 2016 to 2018.

The study pegs the increase in 2014 and over the next decade on a number of factors, namely enrollment in Obamacare's exchanges and Medicaid expansion in various states. Other factors were the aging of the U.S. population and stronger economic growth, according to the study published Tuesday in Health Affairs, a health policy journal.

The study's authors, however, could not pinpoint the exact impact Obamacare will have on health spending over the next decade.

It is difficult "to put numbers on certain things, but each plays a slightly different role," said John Poisal, with the CMS Office of the Actuary, during a Tuesday call with reporters.

Other factors led to the increase in health spending in 2014, including a big increase in spending on prescription drugs, which is projected to have grown about 12 percent in 2014 from 2.5 percent in 2013.

The study pegged the increase on new high-cost specialty drugs for hepatitis C and to a lesser extent cancer and multiple sclerosis. The study's authors said they believed, however, that the long-term impact of prescription drug spending will be minimal.

"We are monitoring the different new drugs and what impact they may have and spending growth," said Sean Keehan, with the Office of the Actuary.

He noted that spending on prescription drugs is still likely to be lower than spending on hospital care and physicians.

Many factors could influence the projections as well, such as changes in economic indicators such as the unemployment rate or price growth, according to the release. Plus, the response to Obamacare could change over time.

The projections are based on an analysis of more than 50 years of national health expenditure data, the study said.