Accelerated use of artificial intelligence-associated vocabulary in Japanese surgical journals after 2023

The increased use of artificial intelligence (AI)-based writing tools may influence academic writing styles. This study aimed to evaluate changes in writing styles in Japanese surgical journals using quantitative time-series analysis.

We analyzed articles published between 2015 and 2025 in Surgery Today and Surgical Case Reports. The writing style was quantified using predefined lexical sets for rare and common AI-related words and promotional words. The word density was calculated for each article separately. We conducted interrupted time-series analyses with 2023 as the intervention year. Observed post-2023 values were compared with the expected values based on pre-2023 trends.

Rare-word density showed a marked post-2023 increase, with a significant change in slope (β = 1.05 per year, 95% CI: 1.01-1.10, p < 0.001). The common-word density also increased after 2023 (β = 0.48, 95% CI: 0.46-0.51; p < 0.001). Promotional word density showed a smaller but statistically significant increase in the post-2023 slope (β = 0.34, 95% CI: 0.24-0.44; p < 0.001). For all three measures, the observed post-2023 values exceeded the expected values that were extrapolated from the pre-2023 trends.

Post-2023, the increase in AI-associated lexical marker use in Japanese surgical journals showed accelerated growth compared to the expected long-term trends.