Some companies do well. Some do really well. And then there is a select group of companies whose performance can only be described as ridiculously good. So, take a bow, UnitedHealth (NYSE:UNH), because you certainly still deserve to be included in that group.

For the 22nd straight quarter, UnitedHealth posted 30% or better year-over-year earnings per share growth. Revenue in the first quarter climbed 34% to $10.9 billion, and EPS came in 32% ahead of the year-ago figure. Perhaps even more important, operating cash flow climbed 33% for the quarter and totaled $1.2 billion.

The contributors to growth were pretty much the usual suspects. UnitedHealth managed to add new customers, maintain pricing, control medical costs, and strip out even more operating expenses.

No doubt these are heady days for health-care benefit companies like Motley Fool Stock Advisor recommendation UnitedHealth. Competitors like Coventry (NYSE:CVH), Aetna (NYSE:AET), and WellPoint (NYSE:WLP) have all prospered, as seen in their bottom lines and their stocks' performance.

And why not? Pricing for health insurance plans has been firm, and increases in medical costs have been fairly tame. While the recent mini-boom in new generics has been bad news for big pharma, health plan operators certainly have benefited from lower drug costs.

Of course, at some point this growth will have to slow down. Aging boomers will consume increasing amounts of health care, and next-generation drugs and medical devices are almost always more expensive than their predecessors.

But that doesn't mean that UnitedHealth is going to crash. Size matters in this industry, and UnitedHealth can leverage its size (and its strong balance sheet) to help control costs and keep its prices competitive with other benefit plans.

What's more, the large number of uninsured people in this country is still a growth opportunity for UnitedHealth should it choose to begin targeting this group in earnest with low-cost programs.

Looking at UnitedHealth's valuation, it seems that the market is already factoring in the notion that growth is going to begin to slow. The enterprise value-to-free cash flow ratio is only about 15, and the trailing P/E is about 23 -- both of which are obviously lower than the company's recent growth performance.

Accordingly, assuming that the wheels don't fall off the bus (which I don't think is very likely), UnitedHealth investors will probably come out OK even as growth slows down across the industry.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).