RT Journal Article SR Electronic T1 Applying natural language processing and machine learning techniques to patient experience feedback: a systematic review JF BMJ Health & Care Informatics JO BMJ Health Care Inform FD BMJ Publishing Group Ltd SP e100262 DO 10.1136/bmjhci-2020-100262 VO 28 IS 1 A1 Mustafa Khanbhai A1 Patrick Anyadi A1 Joshua Symons A1 Kelsey Flott A1 Ara Darzi A1 Erik Mayer YR 2021 UL http://informatics.bmj.com/content/28/1/e100262.abstract AB Objectives Unstructured free-text patient feedback contains rich information, and analysing these data manually would require a lot of personnel resources which are not available in most healthcare organisations.To undertake a systematic review of the literature on the use of natural language processing (NLP) and machine learning (ML) to process and analyse free-text patient experience data.Methods Databases were systematically searched to identify articles published between January 2000 and December 2019 examining NLP to analyse free-text patient feedback. Due to the heterogeneous nature of the studies, a narrative synthesis was deemed most appropriate. Data related to the study purpose, corpus, methodology, performance metrics and indicators of quality were recorded.Results Nineteen articles were included. The majority (80%) of studies applied language analysis techniques on patient feedback from social media sites (unsolicited) followed by structured surveys (solicited). Supervised learning was frequently used (n=9), followed by unsupervised (n=6) and semisupervised (n=3). Comments extracted from social media were analysed using an unsupervised approach, and free-text comments held within structured surveys were analysed using a supervised approach. Reported performance metrics included the precision, recall and F-measure, with support vector machine and Naïve Bayes being the best performing ML classifiers.Conclusion NLP and ML have emerged as an important tool for processing unstructured free text. Both supervised and unsupervised approaches have their role depending on the data source. With the advancement of data analysis tools, these techniques may be useful to healthcare organisations to generate insight from the volumes of unstructured free-text data.