## 2 Literature Review
[PERSON] [61] used a bibliometric analysis method to assess the presence, performance, and impact of scientific articles by the National Institute of Health/National Institute of Allergy and Infectious Diseases clinical trials networks. To be specific, they evaluated the articles in three aspects: (1) Assessing the impact of these articles according to journal impact measures; (2) assessing the performance of articles using bibliometric indicators; and (3) assessing the influence of articles by comparing to similar articles. [PERSON] et al. [59] used bibliometrics to review the development of clinical studies on sepsis systematically. They found that studies contributed by scholars from the USA and published by impactful journals were the most likely to be cited. [PERSON] et al. [60] conducted a bibliometric review of studies on radiologic RCTs to analyze their characteristics and qualities. Based on their analysis, it was found that the quantity and quality of radiologic RCTs had dramatically improved, while the quality of methodologies remained suboptimal. [PERSON] et al. [62] assessed the characteristics and quality of acupuncture RCTs. With an increasing number of RCTs investigating the therapeutic value of yoga interventions, [PERSON] et al. [63] adopted bibliometrics to present a thorough overview of the characteristics of relevant randomized yoga trials. [PERSON] et al. [64] aimed to examine whether positive conclusions appeared more in yoga RCTs when they were carried out in India. According to their study, yoga RCTs performed in India were 25 times more likely to reach positive conclusions as compared to those performed somewhere else. In this sense, Indian trials ought to be handled cautiously while assessing yoga's effectiveness for patients from other regions. [PERSON] et al. [65] identified and characterized the most highly cited papers regarding ultrasonography evaluations taking place in the emergency departments. According to their analysis, the most frequently cited papers concerning the adoption of ultrasonography involved various topics, and almost half of the authors of these papers were experts in emergency medicine. There are several research studies presenting discussions on issues regarding NLP-enhanced clinical trial research. For example, by including all the applications or methodological articles leveraging texts to support healthcare and meet customers' needs, [PERSON] and [PERSON] [11] presented a systematic review of articles concerning the application of NLP to clinical and consumer-produced textual data. Their study indicated that although clinical NLP continued to facilitate practical applications with an increasing number of NLP approaches being adopted to process large-scale live health information, there was a need to enable the adoption of NLP in clinical applications available in our daily life. [PERSON] et al. [66] reviewed studies regarding the NLP-enhanced EHRs-driven computational phenotyping, involving the most advanced NLP techniques for the task. Through their review, several implications were obtained. For example, keyword searches, rule-based approaches, and supervised NLP techniques based on machine learning were the most commonly adopted approaches. Second, well-defined keyword search and rule-grounded systems usually achieved high accuracy. Third, classifications based on supervised methods could achieve higher accuracy and was easier to conduct, as compared to unsupervised methods. Besides, advances in machine learning approaches, for example, deep learning, have grown to be popular. Additionally, there was an increasing interest in extracting relations between medical concepts.