kevinmonk / pc4

An electronic health and care record.

PatientCare v4

PatientCare v4 is an electronic health and care patient electronic record system.

Previous versions have been in constant use within NHS Wales, UK since 2008, helping support the care of a range of patients with both neurological and non-neurological disorders.

Version 4 brings together a suite of loosely-coupled modules and a high degree of interoperability with other health and care systems.

It is a work-in-progress, but the many of the backend components are now complete. The front-end applications are small and highly modular, while providing the appearance of a single seamless system. The first applications will be broken-up and common functionality provided in client libraries.

As a result, this is still in an exploratory phase. The division of the project into different repositories and the responsibilities of each repository are not finalised. I expect these to change. The most mature product is pc4-server. It provides a graph-like API for read operations, with 'commands' (mutations) used for write operations. pc4-ward is an experimental front-end.

Even though I expect many of the implementation details to change, the basic principles will not.

There is a high degree of separation between user-facing applications and underlying data and computing services, with adoption of a range of health and care technical standards.

The applications simply ask for data in the structure and format that best suits their need, and the backend services provide those data. Many of the examples use HL7 FHIR data models at the moment, but I have used the same approach to deliver the same data as openEHR archetypes.

• SNOMED CT as a lingua franca, as provided by hermes.
• Organisational and geographical data and computing services, as provided by clods
• Integration with UK NHS data and computing services, as provided by concierge including
  • Staff authentication and authorisation
  • Staff information lookup (photo/job role/title etc)
  • Patient lookup using the national enterprise master patient index
  • Patient Administrative System (PAS) integration within individual health boards
  • Local and national document repository integration - for persistence of clinical documentation

The principles are:

• a focus on data : immutable and standards-based
• open
• modularisation
• first class identifier resolution and mapping
• graph-based queries
• loose-coupling
• clear separation of data, logic and user interface; with user facing applications lightweight, ephemeral and focused on workflow and process, providing multiple user centric views of the same data.
• different semantics for reading data comparing to writing data; we read using a graph API across disparate federated datasets and write using an event model.

Current status

This is a work-in-progress.

I am principally porting functionality from PatientCare v3 into this new architectural design. The immediate priorities are of an electronic referral system for inpatient liaison services across multiple organisations and an e-observations module for the identification of the deteriorating patient. These modules are not present in PatientCare v3, so complement that legacy application. The idea is to build the new application in parallel with the old, with both running together and newer functionality gradually replacing the old as time progresses. This is the Martin Fowler 'strangler' pattern, which suits me a lot, as a single developer working in my spare time, I cannot hope to deliver a big-bang re-write. Instead, I can deliver incrementally.

Components

A core principle is that user-facing applications should be smart in user interactions but dumb in terms of business logic; the latter are delegated to the backend server.

Fetching data from the backend uses a graph API. Changes are made using events, sent to the server.

pc4-server

This is the main server component, providing an API for graph-like queries for reads and writes. Data is pulled into the application, and events are streamed to the server in order to perform effects such as login or recording new data.

At the moment, this component does not initialise or create any database, expecting a fully initialised database for usual operation as part of module 'rsdb'. This is because it is designed to 'wrap' the legacy PatientCare v3 application which currently is responsiblefor database structure and migration. pc4-server can be used without 'rsdb', but at least currently service and project membership relies on legacy rsdb information.

Once pc4 provides most of the functionality available in rsdb, and I am happy that all new development will use pc4 and not rsdb, I will switch the database initialisation and migration to pc4.

pc4-ward

This repository is the first substantial user-facing component.

At the moment, this is an experiment.

Over time, common components will be factored out into a library, so that there may be multiple user-facing applications all sharing the same codebase. It is likely this will adopt a micro-front-end architecture, but that makes no sense at this point. However, the current architecture is designed to evolve gracefully to this model as functionality is added.

It may be that a framework type approach is best, but I've not made any strong decisions about that at the moment.

The current development strands are:

• workflow to make an electronic referral
• multiple sclerosis disease modifying therapy record system
• electronic observations

Mark