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Prevalence, severity, and nature of preventable patient harm across medical care settings: systematic review and meta-analysis

BMJ 2019; 366 doi: (Published 17 July 2019) Cite this as: BMJ 2019;366:l4185

Linked editorial

Preventable harm: getting the measure right

  1. Maria Panagioti, senior lecturer1,
  2. Kanza Khan, PhD candidate1,
  3. Richard N Keers, lecturer2,
  4. Aseel Abuzour, postdoctoral research associate2,
  5. Denham Phipps, lecturer2,
  6. Evangelos Kontopantelis, professor1,
  7. Peter Bower, professor1,
  8. Stephen Campbell, chair1,
  9. Razaan Haneef, foundation year 2 doctor3,
  10. Anthony J Avery, dean4,
  11. Darren M Ashcroft, professor1
  1. 1NIHR Greater Manchester Patient Safety Translational Research Centre, NIHR School for Primary Care Research, Division of Population Health, Health Services Research and Primary Care, University of Manchester, Manchester M13 9PL, UK
  2. 2Centre for Pharmacoepidemiology and Drug Safety, Division of Pharmacy and Optometry, University of Manchester, Manchester, UK
  3. 3Lancashire Teaching Hospitals NHS Foundation Trust, Manchester, UK
  4. 4Division of Primary Care, School of Medicine, University of Nottingham, Nottingham, UK
  1. Correspondence to: M Panagioti maria.panagioti{at}
  • Accepted 30 May 2019


Objective To systematically quantify the prevalence, severity, and nature of preventable patient harm across a range of medical settings globally.

Design Systematic review and meta-analysis.

Data sources Medline, PubMed, PsycINFO, Cinahl and Embase, WHOLIS, Google Scholar, and SIGLE from January 2000 to January 2019. The reference lists of eligible studies and other relevant systematic reviews were also searched.

Review methods Observational studies reporting preventable patient harm in medical care. The core outcomes were the prevalence, severity, and types of preventable patient harm reported as percentages and their 95% confidence intervals. Data extraction and critical appraisal were undertaken by two reviewers working independently. Random effects meta-analysis was employed followed by univariable and multivariable meta regression. Heterogeneity was quantified by using the I2 statistic, and publication bias was evaluated.

Results Of the 7313 records identified, 70 studies involving 337 025 patients were included in the meta-analysis. The pooled prevalence for preventable patient harm was 6% (95% confidence interval 5% to 7%). A pooled proportion of 12% (9% to 15%) of preventable patient harm was severe or led to death. Incidents related to drugs (25%, 95% confidence interval 16% to 34%) and other treatments (24%, 21% to 30%) accounted for the largest proportion of preventable patient harm. Compared with general hospitals (where most evidence originated), preventable patient harm was more prevalent in advanced specialties (intensive care or surgery; regression coefficient b=0.07, 95% confidence interval 0.04 to 0.10).

Conclusions Around one in 20 patients are exposed to preventable harm in medical care. Although a focus on preventable patient harm has been encouraged by the international patient safety policy agenda, there are limited quality improvement practices specifically targeting incidents of preventable patient harm rather than overall patient harm (preventable and non-preventable). Developing and implementing evidence-based mitigation strategies specifically targeting preventable patient harm could lead to major service quality improvements in medical care which could also be more cost effective.


  • Contributors: The original idea for the research was developed by MP, DMA, RNK, DP, PB, AJA. MP conducted the analysis with input from KK, EK, DMA, RNK, DP, AA, PB, and AJA. MP and KK conducted the searches, study selection, quality assessments, and other data extraction. MP, KK, and DMA wrote the paper. All authors interpreted the findings and contributed to critical revision of the manuscript. All authors had full access to the data in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. MP is the guarantor. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding: This study was funded by the UK General Medical Council (RMS 113361). The NIHR Greater Manchester Patient Safety Translational Research Centre (GMPSTRC-2012-1) funded the corresponding author’s time spent in this project. MP, EK, and PB are also co-investigators in the Evidence Synthesis Working Group (project 390), which is supported by the NIHR School for Primary Care Research. The research team members were independent from the funding agencies. The views expressed in this manuscript are those of the authors and not necessarily those of the General Medical Council, the National Health Service, the NIHR, or the Department of Health. The funders had no role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; and the preparation, review, or approval of the manuscript.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at and all other authors declare no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: Not required.

  • Data sharing: No additional data are available.

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

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