Digital Health Standards: Solving Interoperability with HIEs

Standards and interoperability are foundational to modern digital health systems. They enable different applications to exchange and use data consistently, which can be the difference between timely care and missed opportunities. Understanding these concepts helps illustrate how lives can be saved through coordinated information flow.

Part 1 – Case Study: The Need for Communication

In the fictional country of O'nessa, Lucy, the National Immunisation Officer, and Isaac, the District Health Officer for Umbaya, plan a child vaccination campaign. The campaign requires two critical data points: the number of children needing vaccination and the current vaccine stock at each service delivery site. These data reside in two separate applications—OpenLMIS, which tracks vaccine availability, and DHIS2, which records eligible children. Because the applications use different vocabularies and grammars, they cannot communicate directly. The resulting manual data extraction is labor‑intensive, error‑prone, and diverts staff from decision‑making.

Part 2 – The Quadratic Cost Problem of Direct Integration

Lucy and Isaac initially consider a direct, bi‑directional integration between OpenLMIS and DHIS2, writing custom code to translate data. While this works for two systems, Isaac’s district runs multiple health programs, each with its own application, and Lucy must coordinate across many districts. Adding each new application multiplies the required connections: two apps need one link, three apps need three links, four apps need six, and five apps need ten. The number of connections grows quadratically, not linearly, so any change in one system forces updates across all linked systems. This rapidly escalates costs and complexity, making direct integration unsustainable.

Part 3 – Standards and Interoperability as the Solution

Standards are officially approved rule sets that ensure uniform information sharing across applications. Semantic standards provide a common vocabulary—e.g., using vax.dpt for the DPT vaccine and facility145 for a specific health center—so different systems refer to the same concepts with identical terms. Syntactic standards define a shared grammar that tells applications how to combine those terms into meaningful messages.

A Health Information Exchange (HIE) embodies these standards within a country’s enterprise architecture. Acting as a central translator, an HIE receives data from each application, maps it to the common vocabulary and grammar, and routes it to other systems in real time. Because every application only needs to connect to the HIE, adding a new system requires a single link, and updates affect only the HIE, not all other connections. OpenHIE is an example of such an architecture.

Investing in standards and an HIE makes interoperability cheaper and more reliable. Lucy and Isaac can instantly access combined data on children needing vaccines, current stock, and ordering needs, ensuring that vaccination targets are met. Moreover, the HIE reveals population‑level trends that were previously hidden, enabling timely, evidence‑based decisions that improve health outcomes across all demographics.