Quality and Reliability of Down Syndrome Educational Videos on TikTok and Bilibili: A Cross-Sectional Analysis

Objective This study aims to assess the quality and reliability of educational videos pertaining to Down syndrome (DS) available on TikTok and Bilibili, to compare differences between platforms and content creators, and to examine the relationship between video characteristics and viewer engagement. Methods A cross-sectional search conducted on November 10, 2025, identified relevant videos using the keyword "Down syndrome." Eligible videos were subjected to data extraction and evaluated through a blinded assessment utilizing the Global Quality Score (GQS) and a modified version of DISCERN (mDISCERN). Differences between groups and correlations were analyzed using nonparametric statistical tests. Results There were 274 videos in all, 144 from TikTok and 130 from Bilibili. TikTok videos were shorter (74 s vs. 158.5 s, P  < 0.001) but had more people watching them (all P  < 0.01). There was more diagnostic content on TikTok (78.5% vs. 26.2%). TikTok also had better GQS and mDISCERN scores ( P  = 0.008; P  < 0.001). Healthcare professionals created the highest-quality content ( P  < 0.001), while individual users generated the lowest-quality content but garnered more likes and favorites. There were weak links between video quality and engagement. Conclusion Videos about DS are very different on different platforms. TikTok has better and more medically accurate content, while Bilibili has more noise in its themes. Professional content is more accurate but less interesting, which shows that communication strategies need to be tailored to the platform and that medical information needs to be better monitored.