Of the $17m the app was believed to have cost, $4.27m was spent on buying smart devices for staff to implement SmartHealth, as well as support services, a public information programme, and system integration.
The app was championed by former DHB chief executive Dr Nigel Murray, who spent tens of thousands of taxpayer dollars travelling overseas and around New Zealand learning about and promoting SmartHealth, before he resigned in October amid an expenses scandal.
The proposal for HealthTap was presented to and signed off by the board in one month, in mid-2015.
The strategic business case and the cost of signing up with HealthTap have never been released publicly despite repeated requests under the Official Information Act.
Interim chief executive Derek Wright called for the independent review of HealthTap ahead of contract renewal negotiations with the Silicon Valley interactive health company in May next year, following a two-year trial.
As part of the review the DHB will also look at patient acceptance of the service, the reasons for any reluctance or inability by doctors to use the technology, the benefits of implementing the app so far, and whether HealthTap will work with other regional clinical systems.
Wright previously said the review is not about discontinuing SmartHealth but whether to continue with HealthTap as the provider or move to a "homegrown" service.
The board will discuss the full terms and references of the review at Wednesday's monthly meeting.
Wright wants the review to get under way before Christmas.
Meanwhile Murray is to be removed as a director of HealthShare, the company set up by the five Midland region district health boards to manage shared services, and replaced by Wright.