While the progressive flank of the Democratic Party has coalesced around proposals to enact a government-run health system to achieve universal health coverage, such as Sen. Bernie Sanders’ (I-Vt.) “Medicare for All” plan, skeptics have sounded the alarm on the adverse effects for providers, warning that millions of newly insured Americans could overburden hospitals and cause lengthy wait times to see a doctor.

But new research published in the Annals of Internal Medicine found that the enactment of the two most sweeping health reform laws in American history — Medicare and Medicaid in 1966 and the Affordable Care Act in 2014 — did not spur a surge in overall hospital use, which remained stable in the wake of both expansions.

The study, led by Physicians for a National Health Plan President Adam Gaffney, used data from the National Health Interview Survey (conducted from 1962-1970) and the Medical Expenditure Panel Survey (2008-2015) to analyze how previous health insurance expansions in the United States affected utilization of inpatient services. Utilization was measured as a function of hospital discharge rates and days spent in the facility.