FAcet-joint Injection Clinical and Cost-effective Trial (FACET)

Design

This study seeks to examine the feasibility of undertaking a fully powered double-blind randomised controlled trial. Patients with non-specific low back pain of more than three months' duration with confirmed facet-joint disease will be individually randomised 1:1 to receive facet-joint injections plus a combined physical and psychological programme (intervention group) or to a sham (placebo) procedure plus a combined physical and psychological programme (control group).

Setting

The feasibility study will be conducted in three hospital-based pain medicine centres: Barts Health NHS Trust (formerly Barts and The London NHS Trust), Basildon and Thurrock University Hospitals NHS Foundation Trust, and The Walton Centre NHS Foundation Trust.

Target population

Patients will be recruited from pain, spinal and musculoskeletal clinics at the three participating NHS centres and their associated community clinics. Patients will be referred by their general practitioners with low back pain requiring further specialist assessment, for reasons such as uncertain diagnosis, failure of conservative treatment, or expectation of therapeutic interventions. A screening visit will be used to identify eligible patients i.e. pain of at least 3 months' duration and an average pain intensity numerical rating score (NRS) of at least 4/10 in the 7 preceding days, signs and symptoms of facet-joint disease including bilateral localised paraspinal tenderness at 2 lumbar levels, and have received two components of NICE-defined best non-invasive care (education and one of: physical exercise programme, acupuncture, or manual therapy).

Health technologies being assessed

Facet-joint injections of local anaesthetic and steroid for non-specific low back pain. (Delivered in this study as four X-ray guided intra-articular facet-joint injections through a spinal needle at two lumbar levels bilaterally, using 0.5ml 0.5% bupivacaine + 20mg methylprednisolone per joint, under fluoroscopic guidance.)

Measurement of costs and outcomes

The primary outcomes for this feasibility study include: patient recruitment and attrition rates, levels of patient completion of outcomes, acceptability of the study design to patients and clinicians, fidelity of sham injection and process of blinding, and collection of variance outcome data to inform a future sample size calculation.

The investigators have proposed stopping rules for progression to a main trial. The proposed outcomes for the main trial have been selected in accord with IMMPACT recommendations for chronic pain trials and include: pain assessment, psychological well-being, health-related quality of life, functional disability, health care utilisation including analgesic usage, lost productivity and complications/level of adverse events. Outcomes will be collected at clinic visits at baseline (pre-randomisation) and at 6 weeks, 3 months, and 6 months post-randomisation.

Sample size

The investigators will recruit a total of 150 patients who will undergo a diagnostic facet-joint injection to determine eligibility to participate (test positive for facet-joint disease). Sixty participants (40% of all recruited) are expected to have a positive response to the diagnostic test; these 60 patients will be randomly and equally allocated to intervention and control groups. Assuming up to a 33% attrition rate, the investigators will have >24 complete data sets per arm at the end of the study. This sample size will allow us to achieve our various feasibility objectives.

Project timetables including recruitment rate

A retrospective audit of patient throughput in participating clinics shows that recruitment to achieve 30 patients per treatment arm is readily feasible in the time frame of this study. From 1000 new patient attendances for low back pain at the pain services, the investigators expect approximately 1 in 4 patients to be eligible to enter the study. This is based on our clinical experience and published studies based on responses to controlled diagnostic facet-joint injections, performed in accordance with the criteria established by the International Association for the Study of Pain. Of these 250 patients, approximately 60% (150) will consent to enter the study, of whom approximately 40% (60 patients) are expected to have a positive response from diagnostic medial branch nerve blocks.

The investigators anticipate that the project will take a total of 21 months to complete.