The POiSE Study

Predictors of outcome in sciatica patients following an epidural steroid injection: a prospective observational cohort study.


Sciatica can be very painful and is usually due to a disc herniation (“bulging” or “slipped” disc) pressing on a spinal nerve. For some patients the pain persists and one management option, if the magnetic resonance imaging (MRI) scan confirms a disc herniation, is a spinal epidural steroid injection (ESI). The ESI aims to relieve leg pain, improve function and reduce the need for spinal surgery. For some patients they work well, but not for others. The aims of this study are to test factors, including patient characteristics, clinical examination and imaging findings that help us to predict who does well and who doesn’t after an ESI.

This study will recruit 439 sciatica patients considered by the treating clinician as suitable for an ESI. Patients who have an ESI will take part as well as patients who are suitable for an ESI but don’t go on to have this treatment (for example their symptoms recover while waiting for the ESI). Participants will receive weekly text messages until 12 weeks following their ESI and at 24 weeks following their ESI, asking about their leg pain severity. Participants will also complete questionnaires at baseline, and at 6 weeks, 12 and 24 weeks following their ESI. Participants that do not have the injection will be texted weekly for 18 weeks and at 30 weeks and will receive questionnaires at baseline, 12 weeks, 18 and 30 weeks. Using this information, the study will aim to determine what combination of factors predicts who does well and who doesn’t after an ESI and whether the effects of these factors differ in the group who did not have an ESI. This research will mean clinicians can offer sciatica patients better information about their likelihood of improvement following ESI, and support patient and clinical decision-making about this treatment.

Chief Investigator: Dr Siobhan Stynes
Associate Investigator: Dr Siobhan Stynes
Study Coordinator: Andrea Cherrington
Sponsor / reference number: Keele University / RG-0321-21
Funder / reference number: HEE/NIHR ICA Programme Clinical Lectureship / NIHR300441
UKCRN study portfolio reference number: 50135
Registration reference number: Research Registry: 6844
Start date: 1 Jul 2020
End date:  31 May 2024

Study design

This is an observational cohort study.

Aim and objectives

The principal research question is: In adults with sciatica who are referred for an Epidural steroid injection (ESI) to help relieve their sciatica leg pain symptoms, can we predict who does well and who does not after the ESI using information from the patient characteristics, clinical examination and MRI findings?

There are three primary objectives: 

  1. To describe the characteristics and overall outcomes (prognosis) of patients with sciatica who are suitable for an ESI by looking at (i) all patients in the study, (ii) those who have an ESI and (iii) those who do not have an ESI.
  2. Identify if any individual characteristics (prognostic factors) that expert clinicians think are important for predicting outcome following ESI, do in fact predict outcome for leg pain at 2, 6 and 12 weeks following ESI.
  3. Develop prognostic models (particular combinations of patient, clinical assessment or imaging characteristics) that a clinician could use with a sciatica patient to help predict their change in leg pain intensity at 6 weeks following an ESI.