All data relevant to the study are included in the article or uploaded as supplementary information. The authors of this study agree to share data underpinning this study in the form of web supplements available from the University of Bath Research Data Archive. The raw data poses no risk to anonymity of individuals as it draws on publicly available reports concerning financial transfers between organisations. The reference for this dataset is: Ozieranski, P., Csanadi, M., Rickard, E., Mulinari, S., in press. Underreporting of drug industry payments to patient organisations in the UK (2012-2016). Bath: University of Bath Research Data Archive. https://doi.org/10.15125/BATH-00784.