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Background RCTs are essential in guiding clinical decision-making but are difficult to perform, especially in surgery. This review assessed the trend in volume and methodological quality of published surgical RCTs over two decades. Methods PubMed was searched systematically for surgical RCTs published in 1999, 2009, and 2019. The primary outcomes were volume of trials and RCTs with a low risk of bias. Secondary outcomes were clinical, geographical, and funding characteristics. Results Some 1188 surgical RCTs were identified, of which 300 were published in 1999, 450 in 2009, and 438 in 2019. The most common subspecialty in 2019 was gastrointestinal surgery (50.7 per cent). The volume of surgical RCTs increased mostly in Asia (61, 159, and 199 trials), especially in China (7, 40, and 81). In 2019, countries with the highest relative volume of published surgical RCTs were Finland and the Netherlands. Between 2009 and 2019, the proportion of RCTs with a low risk of bias increased from 14.7 to 22.1 per cent (P = 0.004). In 2019, the proportion of trials with a low risk of bias was highest in Europe (30.5 per cent), with the UK and the Netherlands as leaders in this respect. Conclusion The volume of published surgical RCTs worldwide remained stable in the past decade but their methodological quality improved. Considerable geographical shifts were observed, with Asia and especially China leading in terms of volume. Individual European countries are leading in their relative volume and methodological quality of surgical RCTs.

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