The RELIEF feasibility trial: topical lidocaine patches in older adults with rib fractures.

Background: Lidocaine patches, applied over rib fractures, may reduce pulmonary complications in older patients. Known barriers to recruiting older patients in emergency settings necessitate a feasibility trial. We aimed to establish whether a definitive randomised controlled trial (RCT) evaluating lidocaine patches in older patients with rib fracture(s) was feasible.

Methods: This was a multicentre, parallel-group, open-label, feasibility RCT in seven hospitals in England and Scotland. Patients aged ≥65 years, presenting to ED with traumatic rib fracture(s) requiring hospital admission were randomised to receive up to 3×700 mg lidocaine patches (Ralvo), first applied in ED and then once daily for 72 hours in addition to standard care, or standard care alone. Feasibility outcomes were recruitment, retention and adherence. Clinical end points (pulmonary complications, pain and frailty-specific outcomes) and patient questionnaires were collected to determine feasibility of data collection and inform health economic scoping. Interviews and focus groups with trial participants and clinicians/research staff explored the understanding and acceptability of trial processes.

Results: Between October 23, 2021 and October 7, 2022, 206 patients were eligible, of whom 100 (median age 83 years; IQR 74-88) were randomised; 48 to lidocaine patches and 52 to standard care. Pulmonary complications at 30 days were determined in 86% of participants and 83% of expected 30-day questionnaires were returned. Pulmonary complications occurred in 48% of the lidocaine group and 59% in standard care. Pain and some frailty-specific outcomes were not feasible to collect. Staff reported challenges in patient compliance, unfamiliarity with research measures and overwhelming the patients with research procedures.

Conclusion: Recruitment of older patients with rib fracture(s) in an emergency setting for the evaluation of lidocaine patches is feasible. Refinement of data collection, with a focus on the collection of pain, frailty-specific outcomes and intervention delivery are needed before progression to a definitive trial.

Trial registration number: ISRCTN14813929.