(Bloomberg Business) — The national medical bill may be back to growing faster than gross domestic product. After five years of historically slow growth, new data show U.S. health care spending accelerated significantly in 2014.

The analysis, from the Altarum Institute research group and based on preliminary government data, shows health spending increasing by 5 percent last year, compared to 3.6 percent in 2013. If confirmed by the final tally, health care spending during 2014 would mark the biggest jump since before the recession.

Economists don't know how much of the recent slowdown was due to the recession and how much came from real changes to the health care payments and delivery system. Millions of Americans lost their jobs — and their health insurance — in the wake of the 2008 financial crisis and recession. The Affordable Care Act, passed in 2010, introduced some measures to control health care costs, including penalties for hospitals whose Medicare patients are readmitted within 30 days of a hospital stay.