Outcome Health, a hot Chicago advertising startup that closed a $500 million round in May, is now facing allegations in a Wall Street Journal story that it provided misleading data to advertisers.

A startup that essentially digitizes educational health information, Outcome Health charges medical device companies, pharmaceutical companies and other life science businesses to display advertising on the Outcome Health tablets and devices, which are installed in doctor’s offices and waiting rooms.

Outcome Health’s latest round reportedly gave the company a $5.5 billion valuation — making it the most valuable startup in Chicago, and one of the most valuable companies outside of the coasts.

According to the Wall Street Journal’s Rolfe Winkler, some Outcome Health staffers “provided inflated data to measure how well ads performed, created documents that inaccurately verified that ads ran on certain doctors’ screens and manipulated third-party analyses showing the effectiveness of the ads, according to some of these people and documents.”

The charges are notable because Outcome Health charges clients based upon how many screens the client’s ad is displayed upon, pulled from a desired list of practitioner offices given to Outcome Health by the client.

And according to the Journal’s sources, Outcome Health sometimes charged clients double the price they should have been charged.

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