That may sound logical. The wealthy get more of everything, right? But the authors point out that that was hardly the case in past decades. For instance, the poor received 14 percent more medical services in 1977 than the wealthy, a situation that the authors argue is a logical outcome of the greater health challenges facing low-income people.

The study does not include years since the implementation of the Affordable Care Act. Other studies have shown that the ACA has reduced disparities in insurance coverage, leading to big reductions in uninsured rates among low-income and minority populations.

However, Woolhandler and Himmelstein argue the landmark health law will not do enough to reduce disparities because it largely enshrines the high-cost private insurance industry’s role in health care.

They highlight, for instance, that the average deductible has increased 255 percent in the past decade. One of the constant complaints about ACA plans has been the high deductibles that many low or middle-income customers say they can’t afford to cover in the event of an emergency.

“That kind of insurance is akin to a hospital gown: it gives the impression that you’re covered, but doesn’t actually cover your butt,” they quip.

Other medical professionals have criticized the narrow networks in many ACA plans, arguing that some plans include so few nearby providers that many policyholders have avoided crucial preventative care and continued to be forced to resort to expensive, emergency room care, just as the uninsured traditionally have done.