Microdiscectomy compared with transforaminal epidural steroid injection for persistent radicular pain caused by prolapsed intervertebral disc: the NERVES RCT.

BACKGROUND

Sciatica is a common condition reported to affect > 3% of the UK population at any time and is most often caused by a prolapsed intervertebral disc. Currently, there is no uniformly adopted treatment strategy. Invasive treatments, such as surgery (i.e. microdiscectomy) and transforaminal epidural steroid injection, are often reserved for failed conservative treatment.

OBJECTIVE

To compare the clinical effectiveness and cost-effectiveness of microdiscectomy with transforaminal epidural steroid injection for the management of radicular pain secondary to lumbar prolapsed intervertebral disc for non-emergency presentation of sciatica of < 12 months' duration.

INTERVENTIONS

Patients were randomised to either (1) microdiscectomy or (2) transforaminal epidural steroid injection.

DESIGN

A pragmatic, multicentre, randomised prospective trial comparing microdiscectomy with transforaminal epidural steroid injection for sciatica due to prolapsed intervertebral disc with < 1 year symptom duration.

SETTING

NHS services providing secondary spinal surgical care within the UK.

PARTICIPANTS

A total of 163 participants (aged 16-65 years) were recruited from 11 UK NHS outpatient clinics.

MAIN OUTCOME MEASURES

The primary outcome was participant-completed Oswestry Disability Questionnaire score at 18 weeks post randomisation. Secondary outcomes were visual analogue scores for leg pain and back pain; modified Roland-Morris score (for sciatica), Core Outcome Measures Index score and participant satisfaction at 12-weekly intervals. Cost-effectiveness and quality of life were assessed using the EuroQol-5 Dimensions, five-level version; Hospital Episode Statistics data; medication usage; and self-reported cost data at 12-weekly intervals. Adverse event data were collected. The economic outcome was incremental cost per quality-adjusted life-year gained from the perspective of the NHS in England.

RESULTS

Eighty-three participants were allocated to transforaminal epidural steroid injection and 80 participants were allocated to microdiscectomy, using an online randomisation system. At week 18, Oswestry Disability Questionnaire scores had decreased, relative to baseline, by 26.7 points in the microdiscectomy group and by 24.5 points in the transforaminal epidural steroid injection. The difference between the treatments was not statistically significant (estimated treatment effect -4.25 points, 95% confidence interval -11.09 to 2.59 points). Nor were there significant differences between treatments in any of the secondary outcomes: Oswestry Disability Questionnaire scores, visual analogue scores for leg pain and back pain, modified Roland-Morris score and Core Outcome Measures Index score up to 54 weeks. There were four (3.8%) serious adverse events in the microdiscectomy group, including one nerve palsy (foot drop), and none in the transforaminal epidural steroid injection group. Compared with transforaminal epidural steroid injection, microdiscectomy had an incremental cost-effectiveness ratio of £38,737 per quality-adjusted life-year gained and a probability of 0.17 of being cost-effective at a willingness to pay threshold of £20,000 per quality-adjusted life-year.

LIMITATIONS

Primary outcome data was invalid or incomplete for 24% of participants. Sensitivity analyses demonstrated robustness to assumptions made regarding missing data. Eighteen per cent of participants in the transforaminal epidural steroid injection group subsequently received microdiscectomy prior to their primary outcome assessment.

CONCLUSIONS

To the best of our knowledge, the NErve Root Block VErsus Surgery trial is the first trial to evaluate the comparative clinical effectiveness and cost-effectiveness of microdiscectomy and transforaminal epidural steroid injection. No statistically significant difference was found between the two treatments for the primary outcome. It is unlikely that microdiscectomy is cost-effective compared with transforaminal epidural steroid injection at a threshold of £20,000 per quality-adjusted life-year for sciatica secondary to prolapsed intervertebral disc.

FUTURE WORK

These results will lead to further studies in the streamlining and earlier management of discogenic sciatica.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN04820368 and EudraCT 2014-002751-25.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in

WHAT IS THE PROBLEM?

Sciatica or pain related to nerve irritation travelling down the leg is common in young working adults and most likely to be caused by a ‘slipped’ (prolapsed) disc. Although the majority of cases get better on their own and within 4–6 weeks, a significant group of patients struggle with disabling symptoms sometimes beyond 1 year. Consequently, patients struggle to maintain their home and working lives. Many treatments are available for sciatica, but simpler treatments (e.g. pain tablets, physiotherapy and changing one’s lifestyle) are often not very effective and patients have often tried all of them by the time they are seen in hospital to have tests, such as scans, done. Surgery to remove part of the disc is recommended in cases where the pain is accompanied by severe weakness in one or both legs, or where doctors think that nerves may be damaged because patients have bladder, bowel and sexual functioning difficulties (i.e. red flag symptoms). Surgery works well in alleviation of referred leg pain and also to relieve pressure on a physically compressed nerve that may be showing clinical sign of injury/weakness. An alternative to surgery is to inject a mixture of anaesthetic and steroid close to the site of the disc injury and nerve, but at the moment we do not know whether or not these injections work in the long term. They are cheaper and less invasive, with fewer risks than surgery, such as from anaesthetic or infection.

WHAT DID OUR STUDY INVESTIGATE?

This study compared the usefulness of surgery with injections for patients who have had sciatica for < 1 year and who have tried simple remedies but are still in pain. Patients were allocated to have either surgery or the injection. Symptoms (e.g. pain) were assessed after 18 weeks.

WHAT DID WE FIND?

We found that there was no significant difference between surgery and injection at the primary end point. Surgery was not significantly different from injection in terms of clinical outcome and was not cost-effective compared with injection.

OUR CONCLUSION AND RECOMMENDATION

Given the cost of surgery and the risks to patients, we suggest that further studies should be carried out to explore whether or not all patients with sciatica due to a slipped disc should be considered suitable for an injection, unless there is a good reason not to.