Following promising, early results of clinical trials of budesonide, a drug typically used to prevent asthma symptoms, NHS England commissioned the Risk Stratification programme to collaborate with an expert working group. The aim was to develop a platform that could identify and communicate with patients who were at the highest risk of serious illness from COVID-19, as soon as they tested positive 

We worked with our clinical team to identify 10 condition groups and agree the datasets, rules and many clinical codes required for each of these 10 cohorts. Given that the efficacy window for treatment was expected to be around 7 days, it was essential that we developed a platform that could quickly identify potential patients using multiple datasets. 

Building on our previous experience of finding the vulnerable before COVID does, we created Databricks notebooks on the Data Access Environment (DAE) platform to query multiple national datasets hosted there. Whilst most datasets were updated on a regular schedule, such as Systemic Anti-Cancer Therapy (SACT) data, the results from PCR and (later) lateral flow tests could be updated near real-time via the National Pathology Exchange (NPEx) and Second Generation Surveillance System (SGSS).  When the cohort rules were almost ready for clinical assurance, we could determine an average cohorting duration of just over 2 hours. To include contingency time, we scheduled it to run every 3 hours. 

Alongside data engineering, we developed the communications channels and web platform. We engaged with the NHS Business Services Authority to send event-driven emails and SMS messages using the details provided on each positive COVID-19 test. These messages informed patients that they were potentially eligible for treatment and who to contact for help. 

If the patient did not provide contact details or receive messages, a healthcare professional would need to attempt to contact them instead. To allow this, we created the Population Health Platform to provide secure access to these potential patients from any device that supported existing NHS Care Identity Service 2 (NHS CIS2) smartcard authentication. We built the platform on Amazon Web Services (AWS) using serverless technologies that could scale with demand. Weekly scheduled load, soak and spike performance test suites powered by k6, together with static analysis, unit and automated browser testing as part of Continuous Integration and Deployment (CI/CD) continue to assure that changes to the platform function as expected and do not adversely affect it. 

Although budesonide was ultimately not used for COVID-19 treatment, neutralising Monoclonal Antibody treatments (nMAbs) were proving highly effective. Among other benefits, the initial drug, Ronapreve, had been shown to reduce hospital admission or death by around 70%. However, as this is administered by infusion or injection, so patients were required to visit a hospital or healthcare setting. 

A suite of COVID-19 medicines delivery units (CMDU) were set up across England by Integrated Care Systems (ICSs), so we worked with NHS Care Identity Service 2 (CIS2), a secure authentication service used by health and care professionals in England to access national clinical information system. Together, we created a new role code for administrators who would be in contact with patients. We participated in fortnightly calls with NHS England, its regional teams and ICSs and held smaller live proving sessions with them to demonstrate the platform, answer questions and help resolve setup problems prior to release. 

The platform only reacted to positive PCR tests and so relied upon a patient with symptoms of COVID-19 to take a test. As a proactive measure, the entire initial cohort of nearly 1.3 million people were sent communications mid-December 2021 to let them know that they should submit a PCR test result via GOV.UK if they had symptoms of the disease. 

To make this possible, we ran the cohorting rules without the need for a positive PCR test result. People with a registered email address were sent an email and the rest of the cohort were sent letters (including large print, braille and easy read letters for those who needed them). 

There was also a late additional requirement to send these people PCR test kits. Working closely with the UKHSA, we managed to find a way to share this data, and over the course of 2 weeks, they posted at least 99.9% of those kits successfully. The kits are resupplied when used, so people have kits available if they develop symptoms again. 

As the platform neared its release date, the omicron variant arrived and infections rose again. Fortunately, a second nMAb, sotrovimab, and the first COVID-19 antiviral pill, molnupiravir, were approved and considered effective against this new threat. In a challenging run up to the Christmas period, the Population Health Platform was released on 16 December 2021 and, within the first 3 months, more than 80,000 patients were assessed by clinicians across England, contributing to more than 15,000 treatments. 

The launch of NHS Digital’s targeted therapeutics service was a revolutionary step for the NHS. Combined with its supporting platforms, it has enabled the NHS to combine and use multiple sources of patient data in a safe and secure way, to reliably identify the highest risk people in England and help help them to receive the care and support they need, in this case potentially life-saving COVID-19 treatments.  

The fast turnaround of Targeted Therapeutics service to provide a safe and effective system to identify those at higher risk of COVID-19 infection for treatments - and working with the PANORAMIC trial service to highlight potential candidates to test new treatments - has proved the basis for our approach to cohorting as a service (CaaS). CaaS has the potential to provide a re-usable, scalable and consistent platform for patient identification and improve the delivery of direct care for a range of illnesses.