THE FORECAST STUDY: FACTORS PREDICTING THE TRANSITION TO PERSISTENT PAIN IN ACUTE/ SUBACUTE SCIATICA. COHORT BASELINE AND LONGITUDINAL DATA

Conflicts of interest: LR: Paid facilitation of post-graduate courses internationally. SK, MT, FP, KM, WS, CP, CR, SC, MB, GL: No conflicts of interest. GC: Editor in Chief of Health Psychology Review. Director of board of directors, MentalCHealth Care setting NoordWestVlaanderen. JF: Copyright holder of ODI (Oswestry Disability Index). Served on a data monitoring committee for a clinical trial of 2 different surgical approaches to cervical disc herniation (FORVAD). Member of HTA Prioritisation Committee B: Inside hospital Care from 2015-February 2019. Member of HTA Interventional Procedures Panel from 2010–2015. Trustee and board member of 3 spine related charities – Back-to-Back Charity; British Scoliosis Research Foundation and BackCare. Expert instructed by both claimant and defendant solicitors in negligence and person injury cases. GB: Paid consultancy (RNA-seq) with Ivy Farm and Coding.bio . BT: Paid post-graduate lecturing internationally. Co-chair NeupSIG sciatica working group (unpaid). ABS: Paid post-graduate lecturing internationally. Co-chair NeupSig sciatica working group (unpaid). Sources of funding: This project is funded by UKRI and Versus Arthritis as part of the UKRI Strategic Priorities Fund (SPF) Advanced Pain Discovery Platform (APDP), a co-funded initiative by UKRI (MRC, BBSRC, ESRC), Versus Arthritis, the Medical Research Foundation and Eli Lilly and Company Ltd (Grant MR/W027003/1). Additional funding has been received from the Back-to-Back charity to expand longitudinal components of the study. LR is supported by an NIHR Doctoral Fellowship (NIHR305665) and has received support from the CSP charitable trust. ABS is supported by a Wellcome Trust Clinical Career Development Fellowship (222101/Z/20/Z). FP is funded by a Dorothy Hodgkin Career Development Fellowship in Chemistry in association with Somerville College. GB is supported by the Wellcome Trust (223149/Z/21/Z) and Diabetes UK (19/0005984). MT is supported by the Wellcome Trust (203139/Z/16/Z and 203139/A/16/Z) and by the NIHR Oxford Health Biomedical Research Centre (NIHR203316). GC, WS and KRM are partly funded by UKRI and Versus Arthritis as part of the Advanced Pain Discovery Platform (APDP) PAINSTORM (MR/W002388/1). The UKRI and Versus Arthritis (APDP) are the major funders of FORECAST. All other funders provided either some people support, or funded projects with legacy data that we reuse. The views expressed are those of the author(s) and not necessarily those of their funding bodies. Summary of purpose and background FORECAST is a longitudinal cohort study seeking mechanism-related prognostic factors for pain persistence in spine-related leg pain (SRLP). Here we present FORECAST baseline and longitudinal data. Methods Patients with acute/subacute SRLP underwent detailed evaluation across psychosocial, somatosensory, inflammatory, demographic/lifestyle, and clinical measures. A subgroup (100 patients/48 controls) underwent lumbar MRI. Outcome measures were repeated at 3 and 12 months. Results 201 patients and 48 age- and sex-matched controls were recruited (12-months retention rate 94%). At baseline, leg pain and disability were “moderate” on average (average pain (NRS0-10) 6[4], Oswestry Disability Index 28[24])). 59% had “probable” neuropathic pain. Patients reported higher sleep disturbance (PROMIS t-score 55(9) v 45(7)), and lower quality of life (QoL) (EQ-5D health status 60(21) v 86(11)), compared to controls. Quantitative Sensory Testing showed altered nerve function in the leg, with sensory loss and increased pain sensitivity across thermal and mechanical domains in patients. QST in the hand was comparable between groups. MRI revealed more disc-related pathology and nerve root involvement in patients (disc herniation prevalence: 73% v 27%, nerve root involvement: 60% v 25%). At 12 months, 44–63% of patients reported persistent SRLP symptoms. QoL and sleep improved by three months (68(20), 52(9)) and then plateaued (12months 69(21), 51(9)), while leg pain and disability continued to improve (3months 2[3], 16[18]), 12months 1[3], 12[19]). Conclusion Detailed multi-dimensional testing provides a highly characterised picture of people with acute/subacute SRLP. Wide-ranging symptom/impact measures improved rapidly initially followed by plateau or further improvement, though not complete resolution for many patients, by 12 months.