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Validity of data extraction in evidence synthesis practice of adverse events: reproducibility study

BMJ 2022; 377 doi: (Published 10 May 2022) Cite this as: BMJ 2022;377:e069155

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Reporting of adverse events in clinical trials: still room for improvement.

Dear Editor,

Chang Xu et al. (1) reported interesting findings regarding data extraction in systematic reviews of adverse events AEs. As stated in their excellent paper, data extraction errors reached a proportion as high as 85% in systematic reviews examined. Errors were mainly explained by unclear definitions of outcomes assessed.

It has been highlighted in the literature that reporting of AEs is frequently neglected in clinical trials with poor definitions of outcomes (2, 3). Adherence to the CONSORT harms guidelines remains highly variable according to trials and research areas (3). As stated by John PA Ioannidis in response to our review (2, 4), AEs in clinical trials are neglected, restricted, distorted, and silenced. From a public health perspective, this poor reporting can mislead clinical practice and expose patients to harms and safety issues. The rofecoxib case is one public health example where AEs were silenced. The drug withdrawal was delayed despite a number of warnings from scientists regarding its cardiovascular toxicity (5).

In conclusion, efforts are still needed to improve reporting of harms and properly assess the benefit/harm balance in clinical trials.

1. BMJ 2022;377:e069155
2. Pitrou I, Boutron I, Ahmad N, Ravaud P. Reporting of safety results in published reports of randomized controlled trials. Arch Intern Med. 2009 Oct 26;169(19):1756-61. doi: 10.1001/archinternmed.2009.306.
3. Hodkinson A, Kirkham JJ, Tudur-Smith C, Gamble C. Reporting of harms data in RCTs: a systematic review of empirical assessments against the CONSORT harms extension. BMJ Open. 2013;3(9):e003436.
4. Ioannidis JP. Adverse events in randomized trials: neglected, restricted, distorted, and silenced. Arch Intern Med. 2009 Oct 26;169(19):1737-9. doi: 10.1001/archinternmed.2009.313.
5. Topol EJ. Failing the public health--rofecoxib, Merck, and the FDA. N Engl J Med. 2004 Oct 21;351(17):1707-9. doi: 10.1056/NEJMp048286.

Competing interests: No competing interests

13 May 2022
Isabelle Ellen Pitrou
1. Faculty of Medicine and Health Sciences, University of Sherbrooke, Campus Longueuil, QC, Canada 2. Charles-Le Moyne Research Center (CRCLM), Longueuil, QC, Canada
150 Place Charles-Le Moyne, Longueuil, QC J4K 0A8, Canada