title: Analysis of the effect of sentiment analysis on extracting adverse drug reactions from tweets and forum posts.
abstract: The abundance of text available in social media and health related forums along with the rich expression of public opinion have recently attracted the interest of the public health community to use these sources for pharmacovigilance. Based on the intuition that patients post about Adverse Drug Reactions (ADRs) expressing negative sentiments, we investigate the effect of sentiment analysis features in locating ADR mentions.
  
  
  
  We enrich the feature space of a state-of-the-art ADR identification method with sentiment analysis features. Using a corpus of posts from the DailyStrength forum and tweets annotated for ADR and indication mentions, we evaluate the extent to which sentiment analysis features help in locating ADR mentions and distinguishing them from indication mentions.
  
  
  
  Evaluation results show that sentiment analysis features marginally improve ADR identification in tweets and health related forum posts. Adding sentiment analysis features achieved a statistically significant F-measure increase from 72.14% to 73.22% in the Twitter part of an existing corpus using its original train/test split. Using stratified 10×10-fold cross-validation, statistically significant F-measure increases were shown in the DailyStrength part of the corpus, from 79.57% to 80.14%, and in the Twitter part of the corpus, from 66.91% to 69.16%. Moreover, sentiment analysis features are shown to reduce the number of ADRs being recognized as indications.
  
  
  
  This study shows that adding sentiment analysis features can marginally improve the performance of even a state-of-the-art ADR identification method. This improvement can be of use to pharmacovigilance practice, due to the rapidly increasing popularity of social media and health forums.
authors.affiliation: National Centre for Text Mining, School of Computer Science, University of Manchester, Manchester Institute of Biotechnology, 131 Princess Street, M1 7DN Manchester, United Kingdom. Electronic address: Ioannis.Korkontzelos@manchester.ac.uk.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Korkontzelos
authors.affiliation: Department of Biomedical Informatics, Arizona State University, Mayo Clinic, Samuel C. Johnson Research Building, 13212 East Shea Boulevard, Scottsdale, AZ 85259, United States. Electronic address: anikfarj@asu.edu.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Nikfarjam
authors.affiliation: National Centre for Text Mining, School of Computer Science, University of Manchester, Manchester Institute of Biotechnology, 131 Princess Street, M1 7DN Manchester, United Kingdom. Electronic address: Matthew.Shardlow@manchester.ac.uk.
authors.forename: Matthew
authors.initials: M
authors.lastname: Shardlow
authors.affiliation: Department of Biomedical Informatics, Arizona State University, Mayo Clinic, Samuel C. Johnson Research Building, 13212 East Shea Boulevard, Scottsdale, AZ 85259, United States. Electronic address: msarker1@asu.edu.
authors.forename: Abeed
authors.initials: A
authors.lastname: Sarker
authors.affiliation: National Centre for Text Mining, School of Computer Science, University of Manchester, Manchester Institute of Biotechnology, 131 Princess Street, M1 7DN Manchester, United Kingdom. Electronic address: Sophia.Ananiadou@manchester.ac.uk.
authors.forename: Sophia
authors.initials: S
authors.lastname: Ananiadou
authors.affiliation: Department of Biomedical Informatics, Arizona State University, Mayo Clinic, Samuel C. Johnson Research Building, 13212 East Shea Boulevard, Scottsdale, AZ 85259, United States. Electronic address: Graciela.Gonzalez@asu.edu.
authors.forename: Graciela H
authors.initials: GH
authors.lastname: Gonzalez
mesh_terms: D064420:Drug-Related Side Effects and Adverse Reactions; D006801:Humans; D020407:Internet; D060735:Pharmacovigilance; D011634:Public Health; D061108:Social Media
keywords: Adverse drug reactions; Sentiment analysis; Social media; Text mining