How patient reporters identify adverse drug reactions: A qualitative study of reporting via the UK yellow card scheme

Background: Direct reporting of suspected adverse drug reactions (ADRs) to authorities is increasing, but questions remain about how patients identify suspected ADRs and their ability to distinguish between ADRs and other symptoms. Objective: The aim of the study was to determine how reporters to the Yellow Card Scheme (YCS) identify ADRs. Methods: We carried out a qualitative analysis of data from three sources, obtained as part of a larger evaluation of patient reporting to the UK YCS: responses to open questions in postal questionnaires sent to all reporters during March 2008-January 2009 (method 1); telephone interviews with a purposive sample of these reporters (method 2); and the free-text field from completed Yellow Card reporting forms submitted during October 2005- September 2007 (method 3). Results: Method 1 involved 1362 questionnaire respondents (67.8% of the 2008 patient reporters during the study period), 1167 of whom explained how they decided they had experienced an ADR. Temporality was the most common reason for the perceived association, given by 820 (70.2%) respondents. 478 (41.0%) provided information on two or more aspects of temporality, such as onset, changes with dose and re-challenge. A total of 383 (32.8%) respondents used information sources, such as patient information leaflets or discussions with health professionals to confirm associations, including 145 (12.4%) who had also reported a temporal association. Telephone interviews with 27 reporters (method 2) provided detailed explanations of temporal associations, particularly experiences of rechallenge, and data from 230 Yellow Card reports (method 3) showed that, although reporters are not required to explain reasons for their suspicions, 74.8% of submitted reports included a temporal association. These reports also showed evidence of causal theorizing and differential diagnosis. Conclusion: In our study sample, most reporters to the YCS feel able to identify suspected ADRs adequately and describe processes of assessing causality that mirror those in standard algorithms designed for use by health professionals. These findings should help to reduce concerns among health professionals about the ability of patients to identify suspected ADRs when reporting to authorities.