Key Learnings from Running an Extension Study to a Real-World Effectiveness Trial: The Extended Salford Lung Study

The Salford Lung Studies (SLS) were real-world randomised controlled trials set within UK primary care that assessed the effectiveness and safety of initiating once-daily fluticasone furoate/vilanterol versus continuing usual care in patients with chronic obstructive pulmonary disease or asthma. Data were collected for a relatively short period, limiting the study of long-term outcomes. To broaden the capture of SLS patients' data, we undertook the Extended SLS (Ext-SLS), aiming to better understand the patient disease journey and the effects of treatment in a real-world setting, through collection of patient-level data. Here, we present study design information and the challenges and learnings gathered in creating the Ext-SLS.

The Ext-SLS was intended to augment the SLS by collecting retrospective and prospective (up to 10 years from consent) primary and secondary care electronic health record (EHR) data and patient questionnaires. After ethics approval, general practitioners (GPs) obtained consent from SLS patients remotely (mean 3.2 years post-SLS completion). To facilitate GPs identifying eligible patients, a novel EHR-based approach flagged SLS patients who were alive and registered with their original GP. An automated system sent consent forms/questionnaires to patients. Medical data were collected via EHRs; primary care data were extracted from GPs' systems whilst secondary care data were sourced from the UK NHS.

Of the 75 GP sites from the SLS, 35 (47%) declined Ext-SLS participation leaving 4158 potentially eligible patients; 1169 (28%) patients were excluded as GPs could not confirm them as SLS participants or due to incapacity. Of 2989 patients invited, 1189 (40%) consented.

Developing an EHR-based trial extension was achieved, with reasonable consent rates amongst invited patients. The resulting Ext-SLS is a unique and valuable research resource. Leveraging EHRs and technology reduced GP burden, facilitating participation. Initiation of extension studies prior to study close-out may help increase GP and patient participation.