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Getting started with ISiK

What is ISiK?

ISiK is a German standard. It sets rules for how the different computer systems inside a hospital share data with each other. Think of the patient administration system, the lab, the pharmacy, and the billing system, all needing to talk to one another.

The name stands for "Interoperabler Datenaustausch durch Informationssysteme im Krankenhaus," which just means "hospital systems exchanging data in a compatible way." It's required by German law (§373 SGB V) and written by gematik, the national digital health agency, together with the German Hospital Federation (DKG).

Why it was created

For years, hospitals connected their systems using an older messaging method called HL7v2. Here's how that worked: when something happened in one system, like a new diagnosis being entered, it sent a message to another system. But every hospital set this up a little differently, so every connection needed its own custom rules to translate the message correctly.

This caused real problems:

  • Building and maintaining these custom rules was expensive.
  • Only data captured after the rules were in place could be reused. Older data was stuck.
  • Big hospitals ended up with thousands of these rules, which was hard to manage.

ISiK fixes this by using FHIR, an international healthcare data standard, instead. With FHIR, a system can simply ask for the data it needs, whenever it needs it, old or new. No custom translation rules required.

What "Stufe 3" means

ISiK is released in stages, called "Stufen" (German for "steps" or "levels"). Stufe 3 is the current stage. It spells out exactly what data hospital systems must be able to share, and how.

Hospital software vendors have to prove their systems follow these rules. They do this through gematik's official check, called the "Bestätigungsverfahren" (confirmation procedure). Hospitals get a transition period, but after that, they're required to have this in place.

How Kodjin helps

The Kodjin FHIR Server already follows the ISiK Stufe 3 rules. That means hospitals and software vendors don't have to build this support themselves. It's ready to use.

One especially tricky part of ISiK is how hospitals receive reports from other systems, like lab or radiology software. Kodjin has its own solution for this, described on the Document Bundle page.

Official profiles and documentation

If you want to look at the source material yourself, gematik publishes it in two places:

  • Profiles: the FHIR profiles ISiK defines, with their exact technical rules.
  • Implementation guide: the full written specification, including the "Datenobjekte" pages this section is based on.

How a system gets confirmed

Getting a hospital system officially confirmed for ISiK involves two things: testing it, and applying for the confirmation.

Testing. gematik runs a Testportal, where a vendor runs their system against test cases built from the gematik specifications, in gematik's reference environment. A vendor can run the full automated test suite or pick individual test cases, and can export the results, including a PDF test report, once done.

Confirmation. The Bestätigungsverfahren ISiK is gematik's formal confirmation procedure, required by law (§373 SGB V) for software used in hospitals. In short, a vendor: downloads gematik's procedure description, produces test reports (via gematik's ISiK test suite), applies for the confirmation procedure through gematik's shop, and then submits those test reports through gematik's "Titus" portal. If the review is positive, gematik issues a formal confirmation decision (Bestätigungsbescheid); there's a fee for the process, set by gematik's fee schedule.

Kodjin has been through this process and holds gematik's confirmation for ISiK.

What's covered here

All resource types that are covered by ISiK is described in ISiK Stufe 3 data objects overview.