While biotechnology and specialty pharmaceutical companies endure scrutiny over drug costs, medical device companies have avoided that glare. Their sterling first-quarter results have also helped draw investors seeking safety in healthcare.

The stocks have risen enough that they now look relatively expensive, trading as a group at 19 times the next 12 months earnings estimates compared to a five-year average of 15.8 times.

But drug prices could remain an issue through the U.S. presidential election in November, and some investors say medical device companies will keep their appeal if they report solid second-quarter revenue and profits this month. "You still don’t know how nasty this is going to get on the campaign trail," said Teresa McRoberts, portfolio manager at Fred Alger Management in New York. "There are times when things trade at premiums for reasons beyond fundamentals, and right now one of them is the headline risk that I think is going to keep medtech doing OK."

This year, the S&P 500 Health Care Equipment index <.SPLRCMED> has surged about 15 percent, trouncing the roughly 1.5 percent rise for the overall S&P 500 healthcare sector <.SPXHC>.

The eight best-performing stocks in the broader S&P healthcare index in 2016 are medical device companies, including orthopedics company Stryker (>> Stryker Corporation), heart device makers Edwards Lifesciences (>> Edwards Lifesciences Corp) and Boston Scientific (>> Boston Scientific Corporation), and diversified manufacturer C R Bard (>> C R Bard Inc).

Large medical device companies on average posted organic first-quarter revenue growth of 4.8 percent from a year earlier, their best result in at least two years, Barclays analysts said in a recent report.

Since then, executives have been generally positive about U.S. volume trends, the Barclays analysts said.

Bihag Patel, senior research analyst at Nuveen Asset Management in Minneapolis, said if the companies can sustain mid-single-digit revenue growth in the second quarter, the stocks should maintain their positive momentum.

Intuitive Surgical (>> Intuitive Surgical, Inc.) kicks off reporting season for medical device companies on July 19, followed by Abbott Laboratories (>> Abbott Laboratories) on July 20 and Stryker on July 21.

"It’s a group that’s in favor right now, and if you want to be exposed to healthcare it’s very safe right now," Patel said.

Biotech and pharmaceutical shares face heightened risks from criticism over pricing. Last fall, Democratic presidential candidate Hillary Clinton shook the market with a tweet about "price gouging." The approaching Republican and Democratic conventions could put more pressure on the shares, McRoberts said.

"I don’t know if good earnings even get rewarded if it’s right around when you see whatever verbiage comes out of the convention," McRoberts said.

In medtech, Nuveen’s Patel said he liked several cardiovascular device makers including Boston Scientific. He also said shares of orthopedics company Zimmer Biomet Holdings (>> Zimmer Biomet Holdings Inc) are relatively cheap.

Jeff Jonas, portfolio manager with Gabelli Funds, in Rye, New York, favors Abbott, whose shares have lagged this year. But Jonas has been selling some holdings in Medtronic (>> Medtronic PLC) and Johnson & Johnson (>> Johnson & Johnson), which have run up.

"I think there are still pockets of value out there but broadly speaking the sector is expensive," said Jonas.

Another hazard for medtech, according to RBC Capital Markets analyst Glenn Novarro, would be if investors look more favorably at biotech stocks, fueled by exciting clinical data for experimental medicines or by more large-scale acquisitions of biotech companies, similar to Sanofi's (>> Sanofi) recent bid for Medivation (>> Medivation Inc).

"The number one risk to medtech stock performance really is a rotation back into biotech," Novarro said.

(Reporting by Lewis Krauskopf; Editing by David Gregorio)

By Lewis Krauskopf