MobiHealthNews has tracked dozens of market research and industry metrics year-after-year since 2009. It seems as if for every 100 health apps there is a market research report. And there are at least as many digital health reports as there are digital health events. As I'm preparing for our 2014 Digital Health Trends webinar tomorrow, I've been thinking about the mobile health predictions we have covered over the years. A few of them were way back in 2009 and their due dates are almost upon us.

For example, in 2009 ABI Research estimated that the market for wearable wireless sensors was set to grow to more than 400 million devices by 2014. The firm said at the time that demand would be driven by "professional healthcare, home healthcare and sports and fitness markets" but fitness accounted for 90 percent of the market back then. In 2012 ABI Research estimated that 30 million of these "wireless wearable health devices" (as they now called them) were shipped. About 21 million had shipped the year before. That year -- in late 2012 -- while ABI still predicted almost 170 million would ship in 2017, the prospect of 400 million in 2014 seemed unlikely by most any measure.

Another metric -- this one from InMedica in early 2010 -- predicted that the number of gateways used in telehealth applications will increase to more than 1 million in 2014 and to about 3.6 million in 2018. The estimates included both fixed hubs and mobile phones as gateways. There is now a “two to three year window for the current market barriers to be overcome, including demonstrating the benefits of telehealth on a large scale to health insurance companies,” InMedica wrote at the time. In early 2013 InMedica noted that there were 227,000 telehealth patients in the US. The firm predicted 1.3 million telehealth patients by 2017. While no estimate for the number of telehealth patients in 2014 is publicly available, it's unlikely that the few hundred thousand of them would require north of 1 million telehealth gateways. Some of those market barriers to telhealth have been lessened in the meantime though.

In mid-2010 Juniper Research said that remote patient monitoring over cellular networks would save public and private healthare providers in North America between $1.96 billion and $5.83 billion in healthcare costs by 2014. In July 2013 Juniper doubled down and said remote patient monitoring (in general) would save North American providers about $27 billion by 2018. So maybe that prediction is on track?

There's not a whole lot of transparency in the world of market research data, which typically costs a few thousands dollars for access to every 100 pages of data. Firms are constantly dropping reports and don't always share data that can be compared to previous releases. The few data points above do point to inflated expectations -- sometimes wildly so, as many of the 2009 numbers show -- but also growing traction for digital health across the board.

Perhaps the all-time, most widely circulated statistic in mobile health has been Research2Guidance's prediction way back in late 2010 that there would be 500 million people using smartphone health apps by 2015. We'll see soon enough.