Quest Diagnostics (NYSE:DGX) isn't completely recession proof, but it's pretty darn resistant.

Revenue from its drug testing and its risk assessment businesses is fairly sensitive to the economy. Fewer new hires require less drug testing, which resulted in a 16% decline in the drug testing segment. But fortunately, those two businesses make up only 10% of revenue. The other 90% is derived through diagnostic tests that people need no matter what the economic climate is like.

While revenue was up just 1.7% year over year in the fourth quarter, earnings per share were up a more substantial 10% as lower interest payments boosted the bottom line.

Next year looks better. With cost-cutting efforts kicking in, Quest expects to grow annual revenue by 3% and earnings per share by 8% to 15%.

Some of that increase in earnings per share will apparently come from the $500 million share repurchase that the company expects to undertake next year. Unlike the ever growing group of companies -- Citigroup (NYSE:C), KB Homes (NYSE:KBH), and Sears Holdings (NASDAQ:SHLD) just to name a few -- that bought back shares before prices dropped considerably, Quest Diagnostics has done a pretty good job with its purchases. Last year, it repurchased $254 million worth of stock for an average price of just over $46 -- less than what its stock closed at yesterday. While giving the dividend a boost and letting investors choose if they want to reinvest might be a better way to return the cash, investors shouldn't complain too much.

With personalized medicine on the rise, Quest Diagnostic and its archrival, Laboratory Corp. of America (NYSE:LH), have a good long-term future. Tests like the K-ras mutation to see if Amgen's (NASDAQ:AMGN) Vectibix or Bristol-Myers Squibb (NYSE:BMY) and Eli Lilly's Erbitux will work on a patient are a boon to the long-term growth of the diagnostic testing industry.

In good times and bad, people need diagnostic tests, and Quest seems well poised to give them what they need.

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Quest Diagnostics is a Motley Fool Inside Value pick, and Laboratory Corp. of America is a Stock Advisor recommendation. Yes, our analysts are dueling with each other, but for good reason. Find out why with a free trial to the newsletters.

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Sears Holdings is also an Inside Value pick. The Fool has a disclosure policy.