Large Language Models for Detecting Body Weight Changes as Side Effects of Antidepressants in User-Generated Online Content

ObjectiveHealthcare websites allow patients to share their experiences with their treatments. Drug testimonials provide useful information for real-world evidence, particularly on the occurrence of side effects that may be underreported. We investigated the potential of large language models (LLMs) for detecting signals of body weight change as under-reported side effect of antidepressants in user-generated online content. Materials and MethodsA database of 8,000 user-generated comments about the 32 FDA-approved antidepressants was collected from healthcare social websites. These comments were manually annotated under the supervision of drug experts. Several pre-trained LLMs derived from BERT were fine-tuned to automatically classify comments describing weight gain, weight loss, or the absence of reference to a weight change. Zero-shot classification was also performed. Performance was evaluated on a test set by measuring the weighted precision, recall, F1-score and the prediction accuracy. ResultsAfter fine-tuning, most of the BERT-derived LLMs showed weighted F1-scores above 97%. LLMs with higher number of parameters used in zero-shot classification almost reached the same performance. The main source of errors in predictions came from situations where the machine predicted falsely weight gain or loss, because the text mentioned these elements but for a different molecule than the one for which the comment was written. ConclusionEven fine-tuned LLMs with limited numbers of parameters showed interesting results for the detection of adverse events from online patient testimonials, suggesting they can be used at scale for real-world evidence.