Published on in Vol 26 (2024)

Preprints (earlier versions) of this paper are available at, first published .
Using Large Language Models to Support Content Analysis: A Case Study of ChatGPT for Adverse Event Detection

Using Large Language Models to Support Content Analysis: A Case Study of ChatGPT for Adverse Event Detection

Using Large Language Models to Support Content Analysis: A Case Study of ChatGPT for Adverse Event Detection

Research Letter

1Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, La Jolla, CA, United States

2Qualcomm Institute, University of California San Diego, La Jolla, CA, United States

3Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, CA, United States

4Altman Clinical Translational Research Institute, University of California San Diego, La Jolla, CA, United States

5Department of Computer Science, Johns Hopkins University, Baltimore, MD, United States

6Department of Biomedical Informatics, University of California San Diego, La Jolla, CA, United States

Corresponding Author:

Eric C Leas, MPH, PhD

Herbert Wertheim School of Public Health and Human Longevity Science

University of California San Diego

9500 Gilman Drive

Mail Code: 0725

La Jolla, CA, 92093

United States

Phone: 1 951 346 9131


This study explores the potential of using large language models to assist content analysis by conducting a case study to identify adverse events (AEs) in social media posts. The case study compares ChatGPT’s performance with human annotators’ in detecting AEs associated with delta-8-tetrahydrocannabinol, a cannabis-derived product. Using the identical instructions given to human annotators, ChatGPT closely approximated human results, with a high degree of agreement noted: 94.4% (9436/10,000) for any AE detection (Fleiss κ=0.95) and 99.3% (9931/10,000) for serious AEs (κ=0.96). These findings suggest that ChatGPT has the potential to replicate human annotation accurately and efficiently. The study recognizes possible limitations, including concerns about the generalizability due to ChatGPT’s training data, and prompts further research with different models, data sources, and content analysis tasks. The study highlights the promise of large language models for enhancing the efficiency of biomedical research.

J Med Internet Res 2024;26:e52499



Biomedical text analysis is commonly burdened by the need for manual data review and annotation, which is costly and time-consuming. Artificial intelligence (AI) tools, including large language models (LLMs) such as ChatGPT (OpenAI) [1], could reduce this burden by allowing scientists to leverage vast amounts of text data (including medical records and public data) with short written prompts as annotation instructions [2]. To explore the potential for AI-assisted annotation, we evaluated whether ChatGPT could replicate human identification of adverse events (AEs) about a cannabis-derived product (delta-8-tetrahydrocannabinol) reported in social media posts [3]. AE detection requires reviewing a large amount of unstructured text data to flag a tiny fraction of AE reports, making it an ideal application for AI-assisted annotation [4].


To reduce selective reporting bias, we replicated a peer-reviewed publication, wherein human annotators identified AEs in 10,000 randomly sampled, publicly available posts from a delta-8-tetrahydrocannabiol social media forum (Reddit’s r/delta8) [3]. Human annotators identified potential AE reports (yes or no) and whether the AE was serious according to 6 Food and Drug Administration MedWatch categories (eg, hospitalization) [5].

ChatGPT (gpt-3.5-turbo-0613) was set to the default settings (Temperature=1, Top P=1, Max token limit=1700, Frequency Penalty=0, and Presence Penalty=0); given each Reddit post; and asked to reference annotation instructions identical to those given to human annotators, except for a minor modification for result formatting (ie, requested codes in a comma-delimited format; Multimedia Appendix 1). Since ChatGPT was treated as an additional annotator, we compared ChatGPT’s responses with human annotations using the traditional method for assessing interrater reliability rather than statistics for assessing classifiers (eg, F1-score). Thus, we calculated absolute agreement and prevalence- and bias-adjusted Fleiss κ statistics for any AEs, serious AEs, and each MedWatch category of serious AEs [6]. Analyses were computed with R statistical software (version 4.3.1; R Core Team).

Ethical Considerations

This study was exempted by the University of California San Diego’s human research protection program because the data were public and nonidentifiable (45 CFR §46).

ChatGPT returned misformatted responses (eg, including the text “adverse event” instead of the requested “0” or “1”) in 35 (0.35%) of 10,000 instances. All misformatted responses were interpretable and resolved through normal data-cleaning methods (eg, rule matching). Example posts along with their labels are shown in Table 1. ChatGPT and human annotators agreed on 94.4% (9436/10,000) of labels for any AEs (κ=0.95) and 99.3% (9931/10,000) of labels for any serious AEs (κ=0.96; Table 2). For serious AEs, the lowest agreement was 99.4% (9939/10,000) for “other” serious (but undefined) outcomes (κ=0.98). All specifically defined outcomes (eg, hospitalization) achieved 99.9% (≥9986/10,000) agreement (κ=0.99).

Table 1. Example of posts to the Reddit community r/delta8 and the corresponding categorizations.
Title and textLabelsa
Had to be rushed to the ER after eating an edible. Last week me and my boyfriend bought delta 8 edibles from a vape shop. We were bored and decided it would be a good idea to test it out, we ate two (approximately .1 gram in total). Just a side note, this is was not my first time eating an edible so I didn\'t really think much of it. It took about 40 minutes for the edible to kick in, at first I just felt very heavy and It was super hard to move, so I laid down for about an hour. Eventually I got bored of laying down and got up to go shower...bad decision. According to my boyfriend, when I got up I fainted. I remember waking up to him freaking tf out, it was very hard to breathe, and it felt like my heart was going to burst. They rushed me to the ER because I was barely able to stay conscious. I had a phycotic break, I thought I was dead, kept hearing all kinds of noises, and I completely lost touch with reality. My heart rate was over 165, I also have a heart condition so they had to keep an eye on that too. It was the most terrifying and traumatizing experience, and I\'m still not over it yet. Has anyone gone through this before?Identified as an adverse event report and considered serious with the following outcomes: life-threatening, hospitalization, and other serious adverse event
Help I feel hungover from delta 8. I feel so awful and can\'t stop puking. I took 10 mg last night and still feel horrible today. Any advice?Identified as an adverse event report, but not considered serious
Battery Question. Can someone please recommend and ideal wattage/voltage to use the [BRAND] with? I only have variable wattage/voltage batteries for nicotine vaping and am unfamiliar with batteries used for oils. I’m assuming the former type should work fine as long as I have them set low enough? Any help is appreciated. ThanksNot identified as an adverse event report

aSerious adverse events were defined using the Food and Drug Administration MedWatch health outcome categories, which include life-threatening; hospitalization; disability or permanent damage; congenital anomaly or birth defect; required intervention to prevent permanent impairment; or other serious event.

Table 2. Accuracy of ChatGPT in replicating human identification of adverse events in r/delta8 posts (N=10,000) and the categorization of adverse events to the Food and Drug Administration MedWatch outcome categories.
MedWatch categories and ChatGPT responseHuman annotationAgreement, n (%)κ statistica

Yes, nNo, n

Labeled as an adverse event report9436 (94.4)0.95



Labeled as a serious adverse event reportb9331 (99.3)0.96



Life-threatening9995 (99.9)0.99




Yes569993 (99.9)0.99


Disability or permanent damage9998 (99.9)N/Ac



Congenital anomaly or birth defect9999 (99.9)N/A



Required intervention to prevent permanent impairment or damage9986 (99.9)0.99



Other serious or important medical events9939 (99.4)0.98



aPrevalence- and bias-adjusted Fleiss κ.

bA composite of any of the 6 adverse event outcomes.

cN/A: not applicable (κ could not be calculated due to no events being found by human annotators).

ChatGPT demonstrated near-perfect replication of human-identified AEs in social media posts using the exact instructions that guided human annotators. Despite significant resource allocation, automating AE detection has seen limited success. Many studies (eg, social media studies) often omit performance metrics such as agreement with ground truth altogether [7]. The LLM and prompt used outperformed the best-performing specialized software for detecting AEs from text data (agreement=94.5%; κ=0.89), which relied on structured and human-curated electronic discharge summaries [8].

We note a few limitations. First, we did not have any measures from the replicated study to estimate time or cost savings attributable to using an LLM. However, these savings would be considerable. If a human annotated 1 post/min, the replicated study’s estimated completion time would be 166.6 hours (10,000 posts × 60 posts/h), or 20.8 workdays. Conversely, assuming ChatGPT annotated a post in 2 seconds [9], it would take 5.6 hours with no human effort. Second, the social media data analyzed may be included in ChatGPT’s underlying training data, potentially inflating the accuracy reported herein and reducing generalizability. Third, our goal was to replicate human annotation using the exact codebook that trained human annotators and default settings of ChatGPT-3.5-turbo. Although this alone showed promise, further improvements to the prompt, different models (GPT-4 or Llama-2), or alternative model parameter specifications may improve the accuracy. Finally, we only assessed 1 application of an LLM for biomedical text analysis; inaccuracy and label bias may exist in other settings. Further research is needed to capture process outcomes (eg, time savings), apply LLMs to traditional biomedical data (eg, health records), and address more complex methods of annotation (eg, open coding).

While acknowledging its limitations, this case study demonstrates the potential for AI to assist researchers in text analysis. Given the demand for annotations in biomedical research and the inherent time and cost constraints, adopting LLM-powered tools could expedite the research process and consequently scientific discovery.


This work was funded by grant K01DA054303 from the National Institute on Drug Abuse, the Burroughs Wellcome Fund, and the National Institutes of Health (UL1TR001442). The study sponsors took no part in the study design; collection, analysis, and interpretation of data; the writing of the manuscript; or the decision to submit the manuscript for publication.

Data Availability

The corresponding data for the study are available on the first author’s website [10].

Conflicts of Interest

ECL has received consulting fees from Good Analytics. JWA owns equity in Health Watcher and Good Analytics. ND has received consulting fees from Pearl Health. MD owns equity in Good Analytics and receives consulting fees from Bloomberg LP. MH advised LifeLink, a company that developed a health care chatbot, between 2016 and 2020, and maintains an equity position in the company. DMS reports paid consulting for Bayer, Arena Pharmaceuticals, Evidera, FluxErgy, Model Medicines, and Linear Therapies.

Multimedia Appendix 1

Prompt used to train ChatGPT.

DOCX File , 15 KB

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AE: adverse event
AI: artificial intelligence
LLM: large language model

Edited by Q Jin; submitted 06.09.23; peer-reviewed by Y Li, T Wang, L Zhu, A Khosla; comments to author 10.03.24; revised version received 14.03.24; accepted 28.03.24; published 02.05.24.


©Eric C Leas, John W Ayers, Nimit Desai, Mark Dredze, Michael Hogarth, Davey M Smith. Originally published in the Journal of Medical Internet Research (, 02.05.2024.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on, as well as this copyright and license information must be included.