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Does industry funding and study location impact findings from randomized controlled trials of spinal cord stimulation? A systematic review and meta-analysis
  1. Sam Eldabe1,
  2. Sarah Nevitt2,
  3. Sue Copley3,
  4. Michelle Maden2,
  5. Lisa Goudman4,
  6. Salim Hayek5,
  7. Nagy Mekhail6,
  8. Maarten Moens4,
  9. Phillipe Rigoard7,8 and
  10. Rui Duarte9
  1. 1Department of Pain Medicine, The James Cook University Hospital, Middlesbrough, UK
  2. 2Department of Health Data Science, University of Liverpool, Liverpool, UK
  3. 3Anaesthesia and Pain Management, James Cook University Hospital, Middlesbrough, UK
  4. 4Department of Neurosurgery, UZ Brussel, Brussel, Belgium
  5. 5Anesthesiology, Case Western Reserve University, Unviersity Hospitals, Cleveland, Ohio, USA
  6. 6Cleveland Clinic, Cleveland, Ohio, USA
  7. 7PRISMATICS Lab, Poitiers, France
  8. 8Department of Neurosurgery, Poitiers University Hospital, Poitiers, France
  9. 9University of Liverpool, Liverpool, UK
  1. Correspondence to Dr Sam Eldabe, Department of Pain Medicine, The James Cook University Hospital, Middlesbrough TS4 3BW, UK; seldabe{at}


Background/importance Concerns have been raised that effects observed in studies of spinal cord stimulation (SCS) funded by industry have not been replicated in non-industry-funded studies and that findings may differ based on geographical location where the study was conducted.

Objective To investigate the impact of industry funding and geographical location on pain intensity, function, health-related quality of life and adverse events reported in randomized controlled trials (RCTs) of SCS.

Evidence review Systematic review conducted using MEDLINE, CENTRAL, EMBASE and WikiStim databases until September 2022. Parallel-group RCTs evaluating SCS for patients with neuropathic pain were included. Results of studies were combined in random-effects meta-analysis using the generic-inverse variance method. Subgroup meta-analyses were conducted according to funding source and study location. Risk of bias was assessed using Cochrane RoB 2.0 tool.

Findings Twenty-nine reports of 17 RCTs (1823 participants) were included. For the comparison of SCS with usual care, test for subgroup differences indicate no significant differences (p=0.48, moderate certainty evidence) in pain intensity score at 6 months for studies with no funding or funding not disclosed (pooled mean difference (MD) −1.96 (95% CI −3.23 to −0.69; 95% prediction interval (PI) not estimable, I2=0%, τ2=0)), industry funding (pooled MD −2.70 (95% CI −4.29 to −1.11; 95% PI −8.75 to 3.35, I2=97%, τ2=2.96) or non-industry funding (MD −3.09 (95% CI −4.47 to −1.72); 95% PI, I2 and τ2 not applicable). Studies with industry funding for the comparison of high-frequency SCS (HF-SCS) with low-frequency SCS (LF-SCS) showed statistically significant advantages for HF-SCS compared to LF-SCS while studies with no funding showed no differences between HF-SCS and LF-SCS (low certainty evidence).

Conclusion All outcomes of SCS versus usual care were not significantly different between studies funded by industry and those independent from industry. Pain intensity score and change in pain intensity from baseline for comparisons of HF-SCS to LF-SCS seem to be impacted by industry funding.

  • spinal cord stimulation
  • chronic pain
  • methods

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  • Contributors SE, SN, SC and cowrote the protocol. MMa developed the literature search strategies and conducted the searches. RD, SC and SE performed the study selection. SC, RD and SN extracted the data. SC, MMa and RD conducted the risk of bias assessment. SN performed the data analysis. The results were summarized by RD and SN and interpreted in collaboration with all authors. SE, SN, SC and RD drafted the manuscript. SE, SN, SC, MMa, LG, SH, NM, MMo, PR and RD critically revised the manuscript for important intellectual content and approved the final version of the manuscript. All authors had full access to all data in this study and take complete responsibility for the integrity of the data and accuracy of the data analysis. SE and RD are the guarantors who accepts full responsibility for the finished work and the conduct of the study as well as having access to the data and controlled the decision to publish.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests SE has received consultancy fees from Medtronic, Mainstay Medical, Boston Scientific, and Abbott, outside the submitted work. He has received department research funding from the National Institute of Health Research, Medtronic and Nevro. SN reports consultancy fees from Saluda Medical outside the submitted work. LG is a postdoctoral research fellow funded by the Research Foundation Flanders (FWO), Belgium (project number 12ZF622N). NM has received consulting fees from Boston Scientific, Sollis Therapeutics, Saluda Medical, Nevro, Abbott, Vertos Medical, Nuvectra, and Relievant Medsystems, outside the submitted work; is a Medical Monitor for Mainstay’s RESTORE clinical trial; and has received research support from Avanos 'Halyard', Mallinckrodt, Mesoblast, and Neuros Medical. MMo has received speaker fees from Medtronic and Nevro, outside the submitted work. PR reports grants and personal fees from Medtronic, Abbott and Boston Scientific, outside the submitted work. RD is an employee of Saluda Medical, the employer had no role in the submitted work. He has previously received consultancy fees from Mainstay Medical, Medtronic Ltd and Saluda Medical, outside the submitted work.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.