Free access. Incident reporting has been a mainstay of patient safety initiatives throughout the world, but its purpose and potential for stimulating safety improvements are still much debated. Record review studies of adverse events revealed the nature and scale of harm to patients, and it was initially hoped that incident reporting systems would capture these adverse events on an ongoing basis.1 2 This epidemiological dream was never realised; studies showed that incident reporting was actually very poor at identifying adverse events.3 Furthermore, incident reporting, record review and other systems such as pharmacy reports capture very different types of problems, which means that combining information sources can provide a more complete picture of safety issues.4 5