John Sununu assesses the Affordable Care Act’s impact for Boston Globe readers.

… [M]edia attention has centered lately on the gross number of enrollments — the assumption being that if that number reaches 6 million, the latest White House target, then everyone can declare victory and move on.

But the overarching objective of the Affordable Care Act was never a specific enrollment target or, say, smoothly running software. The goal was to dramatically reduce the number of Americans without health insurance while reducing costs. On that score an honest look at the numbers reveals true failure. The vast majority of those signing up to date were previously covered, a travesty given the bill’s 10-year cost of over $2 trillion.

Begin with the administration’s claim of 5 million enrollments at mid-March, and generously assume they reach 6 million by the deadline. Unfortunately, not all will pay. Analysts at Goldman Sachs estimate that about 20 percent of those who sign up won’t follow through, leaving 4.8 million bona fide Obamacare exchange participants.

How many were uninsured last year? The White House doesn’t seem to know or care. A nationwide survey of those eligible by McKinsey Consulting determined that between 11 and 27 percent were previously without coverage. Accepting the higher figure, the exchanges have taken 1.2 million off the rolls of the uninsured.

Additionally, the law expands Medicaid eligibility. While President Obama recently trumpeted about 6 million new enrollments, nearly half the total comes from states that chose not to expand the program. Most of those remaining were already eligible under the old rules. In short, the law provided new Medicaid coverage for roughly 500,000 people not previously eligible. …

… Finally, the tally of Obamacare beneficiaries should include approximately 3.1 million adults under age 26 who are now required to be covered under their parents’ policy. That leaves a grand total around 5 million, or $400,000 each under the bill’s cost.

From there, the math only gets worse.