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Artificial intelligence versus clinicians: systematic review of design, reporting standards, and claims of deep learning studies

BMJ 2020; 368 doi: https://doi.org/10.1136/bmj.m689 (Published 25 March 2020) Cite this as: BMJ 2020;368:m689
  1. Myura Nagendran, academic clinical fellow1,
  2. Yang Chen, academic clinical fellow2,
  3. Christopher A Lovejoy, physician3,
  4. Anthony C Gordon, professor1 4,
  5. Matthieu Komorowski, clinical lecturer5,
  6. Hugh Harvey, director6,
  7. Eric J Topol, professor7,
  8. John P A Ioannidis, professor8,
  9. Gary S Collins, professor9 10,
  10. Mahiben Maruthappu, chief executive officer3
  1. 1Division of Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Imperial College London, UK
  2. 2Institute of Cardiovascular Science, University College London, UK
  3. 3Cera Care, London, UK
  4. 4Centre for Perioperative and Critical Care Research, Imperial College Healthcare NHS Trust, London, UK
  5. 5Department of Bioengineering, Imperial College London, London, UK
  6. 6Hardian Health, London, UK
  7. 7Scripps Research Translational Institute, La Jolla, California, USA
  8. 8Departments of Medicine, of Health Research and Policy, of Biomedical Data Sciences, and of Statistics, and Meta-Research Innovation Center at Stanford (METRICS), Stanford University, Stanford, CA, USA
  9. 9Centre for Statistics in Medicine, University of Oxford, Oxford, UK
  10. 10NIHR Oxford Biomedical Research Centre, Oxford University Hospitals NHS Trust, Oxford, UK
  1. Correspondence to: M Nagendran, Intensive Care, St Mary’s Campus, Imperial College London, Praed Street, London W2 1NY, UK myura.nagendran{at}imperial.ac.uk (or @MyuraNagendran on Twitter)
  • Accepted 11 February 2020

Abstract

Objective To systematically examine the design, reporting standards, risk of bias, and claims of studies comparing the performance of diagnostic deep learning algorithms for medical imaging with that of expert clinicians.

Design Systematic review.

Data sources Medline, Embase, Cochrane Central Register of Controlled Trials, and the World Health Organization trial registry from 2010 to June 2019.

Eligibility criteria for selecting studies Randomised trial registrations and non-randomised studies comparing the performance of a deep learning algorithm in medical imaging with a contemporary group of one or more expert clinicians. Medical imaging has seen a growing interest in deep learning research. The main distinguishing feature of convolutional neural networks (CNNs) in deep learning is that when CNNs are fed with raw data, they develop their own representations needed for pattern recognition. The algorithm learns for itself the features of an image that are important for classification rather than being told by humans which features to use. The selected studies aimed to use medical imaging for predicting absolute risk of existing disease or classification into diagnostic groups (eg, disease or non-disease). For example, raw chest radiographs tagged with a label such as pneumothorax or no pneumothorax and the CNN learning which pixel patterns suggest pneumothorax.

Review methods Adherence to reporting standards was assessed by using CONSORT (consolidated standards of reporting trials) for randomised studies and TRIPOD (transparent reporting of a multivariable prediction model for individual prognosis or diagnosis) for non-randomised studies. Risk of bias was assessed by using the Cochrane risk of bias tool for randomised studies and PROBAST (prediction model risk of bias assessment tool) for non-randomised studies.

Results Only 10 records were found for deep learning randomised clinical trials, two of which have been published (with low risk of bias, except for lack of blinding, and high adherence to reporting standards) and eight are ongoing. Of 81 non-randomised clinical trials identified, only nine were prospective and just six were tested in a real world clinical setting. The median number of experts in the comparator group was only four (interquartile range 2-9). Full access to all datasets and code was severely limited (unavailable in 95% and 93% of studies, respectively). The overall risk of bias was high in 58 of 81 studies and adherence to reporting standards was suboptimal (<50% adherence for 12 of 29 TRIPOD items). 61 of 81 studies stated in their abstract that performance of artificial intelligence was at least comparable to (or better than) that of clinicians. Only 31 of 81 studies (38%) stated that further prospective studies or trials were required.

Conclusions Few prospective deep learning studies and randomised trials exist in medical imaging. Most non-randomised trials are not prospective, are at high risk of bias, and deviate from existing reporting standards. Data and code availability are lacking in most studies, and human comparator groups are often small. Future studies should diminish risk of bias, enhance real world clinical relevance, improve reporting and transparency, and appropriately temper conclusions.

Study registration PROSPERO CRD42019123605.

Footnotes

  • Contributors: MN and MM conceived the study. MN, YC, and CAL executed the search and extracted data. MN performed the initial analysis of data, with all authors contributing to interpretation of data. JPAI contributed to amendments on the protocol. All authors contributed to critical revision of the manuscript for important intellectual content and approved the final version. MN is the study guarantor. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding: There is no specific funding for this study. MN and YC are supported by National Institute for Health Research (NIHR) academic clinical fellowships. ACG is funded by a UK NIHR research professor award (RP-2015-06-018). MN and ACG are both supported by the NIHR Imperial Biomedical Research Centre. The Meta-Research Innovation Center at Stanford (METRICS) has been funded by a grant from the Laura and John Arnold Foundation. GSC is supported by the NIHR Oxford Biomedical Research Centre and Cancer Research UK (grant C49297/A27294).

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organisation for the submitted work; CAL worked as clinical data science and technology lead for Cera, a technology enabled homecare provider; ACG reports that outside of this work he has received speaker fees from Orion Corporation Orion Pharma and Amomed Pharma, has consulted for Ferring Pharmaceuticals, Tenax Therapeutics, Baxter Healthcare, Bristol-Myers Squibb and GSK, and received grant support from Orion Corporation Orion Pharma, Tenax Therapeutics, and HCA International with funds paid to his institution; HH was previously clinical director of Kheiron Medical Technologies and is now director at Hardian Health; EJT is on the scientific advisory board of Verily, Tempus Laboratories, Myokardia, and Voxel Cloud, the board of directors of Dexcoman, and is an advisor to Guardant Health, Blue Cross Blue Shield Association, and Walgreens; MM is a cofounder of Cera, a technology enabled homecare provider, board member of the NHS Innovation Accelerator, and senior advisor to Bain and Co.

  • Ethical approval: Not required.

  • Data sharing: Raw data are available on request from the corresponding author.

  • The lead author and manuscript’s guarantor (MN) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

  • Dissemination to participants and related patient and public communities: We plan to use social media to help disseminate the findings from this research as well as engaging with patient groups. The timing of this dissemination will begin with the publication of this article and continue during early 2020.

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