Well, not exactly. You'd get a clearer picture if you broke the US population down by demographics.
The US has more immigration, for one thing, and a greater disparity between rich and poor. Our drug problems seem to be worse. Mexicans use our Emergency Rooms for free and then go back to their country so they don't have to pay, but we're stuck with the bill. Or some stay here. Mexican immigrants have lower life expectancy.
Stillborne births are counted differently in some European countries, with a baby sucking one breath in the US being counted as living for one day, while the same baby in some European countries (don't know about the UK) would be called a stillbirth and ignored by the statistics. (Accounting for this still just brings the US up only into the top 15 or so countries in ranking, but it is a factor.)
The high end care in the US is some of the best in the world, and people come here from Europe for cancer treatment. Also, the fact that the US doesn't have price controls and Europe does means that the American market is the primary engine funding drug development. Europe is basically a free rider. If America enacted price controls on drugs (and why shouldn't we, to be economically competitive with the rest of the world) then Europe would see the drugs its cost-controlled medical system had access to dwindle.
Incidentally, the rate of organ transplants in the US is much higher than in Europe.
Also, frankly, the average American diet is awful. To give just one example; we don't test cattle for BSE (Mad Cow) because "it's never been found on this continent" though the lack of testing would make it impossible to find it so it's kindof a circular argument. US cows are slaughtered younger, so symptoms wouldn't appear in infected animals. Also, wild deer have been found with a BSE like prion, indicating that it is, in fact, on this continent. (Avoid US beef like the plague that it is.)
And hydrogenated oils should have been, by the FDAs own standards, approved only as an additive rather than a foodstuff.