The lack of robust evidence of the patient safety measurement in primary and ambulatory care settings can partly be explained by the fragmented nature of this setting described in the introduction. In fact, survey responses suggest that the fragmented nature of primary and ambulatory care ‘systems’ , and lack of overall system governance, are the most important barrier to implementing safety measurement and interventions (see Chapter 4). This means infonnation can rarely be linked. These technical barriers may prohibit capturing accurately the full picture of the frequency and magnitude of patient harm occurring along the patient pathway.