It's purely speculative, but a survey of entrepreneurs working in digital health suggests that Practice Fusion, Castlight Health and ZocDoc could be the next companies in the sector to go public.

Venture capital firm InterWest Partners queried more than 100 entrepreneurs about the future of digital health and found that 26 percent of them thought Practice Fusion, the current darling of the small-practice EHR market, would be the next to hold an initial public offering. Another 21 percent said the next IPO in digital health would be consumer health information platform Castlight, while 19 percent named appointment booking engine ZocDoc.

Castlight has publicly indicated that it is investigating an IPO. Investment bank Goldman Sachs reportedly has been courting ZocDoc for a public offering, and already has invested $25 million in the New York City-based company.

Lower down on the list were AirStrip Technologies, Humedica, SeeChangeHealth, TelaDoc, Doximity and Best Doctors.

Interestingly, Castlight Health and ZocDoc also came up often in response to another question in the survey: "Besides your own, which company do you wish you founded?" While InterWest did not break down these answers by percentage, only by a word cloud, it appears that Google came out on top. AirStrip and EHR giant Epic Systems also had prominent positions.

Epic ranked high in a dubious category. Some 14 percent of respondents said Epic and primary competitor Cerner were the biggest challenge to innovation in healthcare. Leading that list, however, was reimbursement, named by 27 percent, followed by government, at 19 percent. Only 5 percent saw the venture community as the top challenge to healthcare innovation.

Despite the fact that entrepreneurs tend to be viewed as innovators, 14 percent of survey respondents said "disruptive innovation" was the most overused phrase in digital health today. However, that was barely half of the 27 percent who said "gamification of healthcare" had become a trite buzzword and also behind the 23 percent who named "big data" or "predictive analytics."