• by Mark Walsh  @markfwal, January 28, 2009

Signaling continuing consolidation in the online health space, HealthCentral has acquired fast-growing Web health community Wellsphere. Terms of the deal were not disclosed.

Arlington, Va.-based HealthCentral said the deal would boost the size of its online audience from 6 million monthly unique visitors to 10 million. ComScore estimates both sites' traffic at much lower levels: 2.3 million for HealthCentral and 850,000 for Wellsphere.

While the acquisition gives HealthCentral more heft to compete with larger competitors in the category, CEO Chris Schroeder stressed that the merger is as much about synergy as increasing size. He pointed out that Wellsphere's focus on wellness and healthy living topics will complement HealthCentral's health condition-oriented portal. "This gives us expanded reach," he said, adding that the two properties have little overlap in users.

Founded in 2007 by Stanford Business School grads, Wellsphere features a central search box on its home page, much like Google, that allows users to search for information on specific health-related subjects. Results are presented via the site's WellPages, which combine articles, blogs, a Q&A section, and videos on the topic queried from sources ranging from the FDA to health and fitness magazines.

Wellsphere itself boasts 1,500 bloggers, including medical professionals and "expert patients," around various health and wellness subjects. The company is also launching health-related mobile applications through its Wellphone platform, "which we think will have huge ramifications going forward," said Schroeder.

Under the deal, the companies will maintain separate Web sites as well as separate offices on both coasts. But HealthCentral will incorporate Wellsphere's technical expertise, while the startup will benefit from HealthCentral's more established business and ad sales operation, according to Schroeder.

Last fall, the Waterfront Media-owned Everyday Health Network merged with Revolution Health Network to overtake WebMD as the largest online health property, with 26.7 million unique visitors in December 2008. HealthCentral's acquisition of Wellsphere would still not lift the merged entity into the top ten health sites, according to the comScore rankings.

But Schroeder downplayed the comScore figures, suggesting that HealthCentral and Wellsphere had higher-quality audiences than rivals because they have not relied on search engine marketing to drive traffic growth.

"Because our traffic is organic...our audience members arrive more engaged, ready to act, and research shows they do act on what they learn," he said. "We now will be able to deliver measurably better ROI for advertisers on an even larger scale."