The Extended Salford Lung Study: an EHR-based extension of the SLS trials

The Salford Lung Studies (SLS) were real-world effectiveness RCTs of initiating FF/VI vs. usual care (1:1) in asthma and COPD. Data were only collected in SLS for a relatively short period, limiting study of long-term outcomes. The Extended-SLS aims to augment the SLS, collecting 1° and 2° care electronic health record (EHR) data and patient questionnaires. After receiving Ethics approval, GPs remotely consented SLS subjects (mean 3.2 yrs post-completion). To facilitate GPs in identifying eligible patients, a novel EHR-based approach was used to flag subjects who completed the SLS, were still alive and registered with the same GP. An automated system (Docmail) was used to send consent forms/questionnaires direct to patients. Medical data were collected solely via EHRs; a trusted 3rd party extracted 1°-care data from GPs systems and NHS Digital provided linked 2°-care data. Of the 75 GP sites from the original SLS, 35 did not participate, resulting in 4,158 potentially eligible subjects from 40 practices; 18% were excluded as could not be confirmed as SLS subjects or incapacity. Of 2,989 invited, 39% consented to the study (see Figure). We demonstrate that developing an EHR-based, trial extension is achievable with good consent rates. Leveraging of EHRs and technology reduced GP burden, facilitating participation. Initiation of extension studies prior to study close out may help in reducing patient attrition.