According to experts in mHealth (Mobile Health), mobile healthcare is the future of health care and expected revenue of investments in new technologies and smart phones is about 27 billion US dollars by 2017.
Suggest you peruse the last 2-3 years of the Journal of Medical Internet Research JMIR-
http://www.jmir.org/
Despite the hype about Mobile Health it is taking longer to ascertain where the true value is for some areas. NB Big movements in telehealth, patient portals, electronic healthcare records.
Guess following JMIR is really a good idea. I did my PhD on mHealth in Malaysia and my paper will be published in JMIR (will put it up here once it is out). However, you might also check the LifeGuide project from the Uni of Southampton (big multinational e- & mHealth initiative in a number of areas).
I believe in most cases you will find meta analysis about a specific specialty but not all mHealth apps in general... here's an example https://academic.oup.com/ajcn/article/107/2/247/4911449
The use of mobile and wireless technologies to support the achievement of health objectives (mHealth) has the potential to transform the face of health service delivery across the globe. A powerful combination of factors is driving this change. These include rapid advances in mobile technologies and applications, a rise in new opportunities for the integration of mobile health into existing eHealth services, and the continued growth in coverage of mobile cellular networks. According to the International Telecommunication Union (ITU), there are now over 5 billion wireless subscribers; over 70% of them reside in low- and middleincome countries. The GSM Association reports commercial wireless signals cover over 85% of the world’s population, extending far beyond the reach of the electrical grid.
All new information was published by W.H.O. and you can find it through this link https://www.who.int/goe/publications/goe_mhealth_web.pdf