Factors predicting the transition from acute to persistent pain in people with ‘sciatica’-the FORECAST longitudinal prognostic factor cohort
| ISRCTN | ISRCTN18170726 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN18170726 |
| ClinicalTrials.gov (NCT) | Nil known |
| Clinical Trials Information System (CTIS) | Nil known |
| Protocol serial number | Nil known |
| Sponsor | University of Oxford |
| Funders | UK Research and Innovation, Versus Arthritis, National Institute for Health and Care Research |
- Submission date
- 30/01/2023
- Registration date
- 10/02/2023
- Last edited
- 14/10/2025
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Musculoskeletal Diseases
Plain English summary of protocol
Background and study aims
Sciatica is very common and is caused by injured or irritated nerves in the lower back. Sciatica causes pain, tingling or weakness in the leg. It can have a devastating effect on everyday life. For instance, patients cannot complete their normal work or care for their families. Sadly, about one in three patients develops persistent sciatica pain. We currently do not understand why some patients develop persistent pain and why some recover. Previous research has demonstrated that usual clinical findings (e.g., depression or routine MRI) cannot predict persistent sciatica. A different approach is therefore needed to identify who may develop persistent sciatica. This is the goal of the FORECAST study.
FORECAST is performed by a team of medical doctors, neuroscientists, statisticians, and MRI specialists at Oxford University. The team also includes patient partners who help us design and run our study. Our FORECAST study is different to previous studies. Whereas previous studies only included a short clinical examination, we will perform a detailed set of tests. We hope that the detailed tests can predict who develops persistent pain. The questions we hope to answer in the FORECAST study comprise whether the detailed tests identify different subgroups of patients with sciatica and which of these detailed tests predict pain persistence. The FORECAST study is a substudy of the PiPL platform. PiPL aims to understand prognostic factors for pain persistence and the nature of nerve-related pain in patients with different peripheral nerve injuries and includes many different substudies in different patient populations.
Who can participate?
Adults with recent onset of sciatica (symptoms<3 months)
What does the study involve?
The FORECAST study is a substudy of the PiPL study (IRAS 241777). In the first assessment, the team will perform detailed tests. This includes detailed sensory nerve testing (quantitative sensory testing) and a precise set of questionnaires to evaluate the type of pain and emotional well-being. A blood sample will also be taken to look for signs of inflammation. Some patients will receive specialised magnetic resonance imaging to evaluate the microscopic structure of the small nerves in the back. These images are much more detailed and specialised than routine MRI scans. Patients will be contacted again three months and one year later, to ask whether they still have sciatica symptoms. Statistics will be used to identify patient subgroups and to find out which tests predict pain persistence.
What are the possible benefits and risks of participating?
There is no direct benefit to participants, but the information we get might help improve the treatment of people with sciatica in the future.
There are no particular risks to this study. MRI is considered a safe procedure, and we will only invite people with no contraindications to MRI for scanning.
The results of the FORECAST study will help us better understand the complexity of sciatica and who develops persistent pain. The findings will also help future research. For instance, future studies can examine whether giving more specific treatment to patients who are likely to develop persistent pain can reduce chronic pain. It is hoped that the results of the FORECAST study will help reduce suffering and improve the quality of life for patients with sciatica.
Where is the study run from?
University of Oxford (UK)
When is the study starting and how long is it expected to run for?
The PiPL platform study commenced in January 2018 and the FORECAST substudy runs from May 2021 to September 2025
Who is funding the study?
1. UK Research and Innovation (UK)
2. Versus Arthritis (UK)
3. National Institute for Health and Care Research (NIHR) (UK)
Who is the main contact?
Prof Annina Schmid, annina.schmid@ndcn.ox.ac.uk (UK)
Contact information
Principal investigator
Nuffield Department of Clinical Neurosciences
John Radcliffe Hospital
West Wing Level 6
Oxford
OX3 9DU
United Kingdom
 ORCID ID |
0000-0001-7759-0211 |
|---|---|
| Phone | +44 (0)1865 223254 |
| annina.schmid@ndcn.ox.ac.uk |
Scientific
Nuffield Department of Clinical Neurosciences
John Radcliffe Hospital
West Wing Level 6
Oxford
OX3 9DU
United Kingdom
| Phone | +44 (0)1865 223254 |
|---|---|
| annina.schmid@ndcn.ox.ac.uk |
Public
Nuffield Department of Clinical Neurosciences
John Radcliffe Hospital
West Wing Level 6
Oxford
OX3 9DU
United Kingdom
| Phone | +44 (0)1865 223254 |
|---|---|
| annina.schmid@ndcn.ox.ac.uk |
Study information
| Primary study design | Observational |
|---|---|
| Study design | Single-centre prospective longitudinal prognostic factor cohort study |
| Secondary study design | Longitudinal study |
| Study type | Participant information sheet |
| Scientific title | FactORs prEdiCting the trAnsition from acute to persistent pain in people with ‘SciaTica’-the FORECAST longitudinal prognostic factor cohort, a substudy of the PiPL platform |
| Study acronym | FORECAST |
| Study objectives | The FORECAST study is a substudy of the PiPL platform study (IRAS 241777). The aims of the FORECAST study are: 1. To explore mechanism-based subgroups in patients with acute/subacute sciatica 2. To investigate whether a mechanism-based approach can identify factors that predict pain persistence in people with sciatica |
| Ethics approval(s) | Approved 31/05/2018, South Central - Oxford C Research Ethics Committee (Level 3, Block B, Whitefriars Building, Lewis Mead, Bristol, BS12NT, UK; +44 (0)207 1048289; oxfordc.rec@hra.nhs.uk), ref: 18/SC/0263 |
| Health condition(s) or problem(s) studied | Acute/subacute sciatica/low back pain |
| Intervention | The FORECAST study is a prospective longitudinal prognostic factor cohort study involving patients with acute/subacute ‘sciatica’ and healthy age- and gender-matched participants without symptoms of sciatica/low back pain. The study is based on feasibility data and closely informed by patient and public involvement and engagement (PPIE) activities including feedback from our named patient partners, a six-member patient advisory group, and survey results from participants of the feasibility study. The study will be performed and reported according to the guidelines for observational studies (STROBE) and the statement for transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD). The study will include patients with acute/subacute ‘sciatica’ and healthy age- and gender-matched participants without symptoms of sciatica/low back pain. Healthy participants are essential to establish normative values for blood markers, somatosensory profiling and neuroimaging. After a preliminary eligibility screen on the telephone, patients will attend a baseline appointment with a clinically trained investigator (e.g, physiotherapist) at the local University Department. During the baseline appointment, the diagnosis of sciatica will be confirmed, and the prognostic variables will be assessed through a detailed set of clinical phenotyping as described below. Some patients will also undergo an MRI scan of their lumbar spine. We will then follow up with patients over 1 year with monthly pain diaries and the outcomes will be measured at 3 (short-term) and 12 months (long-term). |
| Intervention type | Other |
| Primary outcome measure(s) |
Pain persistence measured using the below at 3 months and 12 months: |
| Key secondary outcome measure(s) |
1. Level of disability in activities of daily living measured using the Oswestry Disability Index at 3 and 12 months |
| Completion date | 30/09/2025 |
Eligibility
| Participant type(s) | Healthy volunteer, Patient |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Sex | All |
| Target sample size at registration | 180 |
| Total final enrolment | 229 |
| Key inclusion criteria | 1. People aged >18 years with a clinical diagnosis of ‘sciatica’ 2. Sciatica symptom onset of the current episode within the past 3 months with a symptom-free period of at least 3 months preceding the current sciatica symptoms 3. A sum score of >4 (on the diagnostic model published by Stynes 2018) will be defined as sciatica (weighted sum score including self-reported sensory changes, below knee pain, leg pain worse than back pain, neurodynamic tests, and neurological deficit) 4. Clinical examination confirms the clinical diagnosis of sciatica and rules out other diagnoses |
| Key exclusion criteria | 1. Presence of other nerve-related disorders (e.g. diabetic neuropathy, stroke) 2. Previous lumbar spine surgery 3. Serious spinal pathologies (e.g. infection, cauda equina syndrome, metastatic lesions) 4. Chronic inflammatory disorders 5. Other pain conditions that may confound assessment (e.g., fibromyalgia) 6. Pregnancy 7. Insufficient command of the English language to obtain consent/complete questionnaires 8. Contraindications to MRI for those selected for scanning |
| Date of first enrolment | 15/05/2022 |
| Date of final enrolment | 23/09/2024 |
Locations
Countries of recruitment
- United Kingdom
- England
Study participating centre
John Radcliffe Hospital
West Wing Level 6
Oxford
OX39DU
United Kingdom
Results and Publications
| Individual participant data (IPD) Intention to share | Yes |
|---|---|
| IPD sharing plan summary | Stored in publicly available repository |
| IPD sharing plan | The datasets generated during and/or analysed during the current study will be stored in a publicly available repository (Alleviate/ https://alleviate.ac.uk) • The type of data that will be shared: All data presented in the final manuscript and outlined in the protocol. • Dates of availability: expected to be available after publication of the main papers. • Whether consent from participants was required and obtained: yes • Comments on data anonymization: data will be anonymised • Any ethical or legal restrictions: Data sharing agreements with Alleviate data hub are already in place. • Any additional comments? For more information on Alleviate hub, see https://alleviate.ac.uk |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Protocol article | 05/04/2023 | 06/04/2023 | Yes | No | |
| HRA research summary | 28/06/2023 | No | No | ||
| Participant information sheet | Participant information sheet | 11/11/2025 | 11/11/2025 | No | Yes |
| Study website | Study website | 11/11/2025 | 11/11/2025 | No | Yes |
Editorial Notes
14/10/2025: The contact confirmed the record is up to date.
01/10/2024: The following changes were made to the study record:
1. The recruitment end date was changed from 30/08/2024 to 23/09/2024.
2. The overall study end date was changed from 30/08/2025 to 30/09/2025.
3. Total final enrolment added.
23/05/2024: The following changes were made to the trial record:
1. The recruitment end date was changed from 15/05/2024 to 30/08/2024.
2. The overall end date was changed from 13/05/2025 to 30/08/2025.
3. The plain English summary was updated to reflect these changes.
06/04/2023: Publication reference added.
10/02/2023: Trial's existence confirmed by NHS HRA.
