Objective To describe the use and characteristics of national confidential enquiries (NCEs) into adverse outcomes of healthcare in high-income countries and to review the evidence of their impact.

Method Systematic search of bibliometric databases plus review of cited references and search of websites. Eleven characteristics of NCEs were extracted. Studies evaluating the impact of three NCEs were searched for. Data were extracted and tabulated, and a narrative review conducted.

Results Establishment of NCEs has been limited with only 27 examples identified in over 50 years and only nine currently functioning. They have been particularly popular in the nations of the UK (17 of the 27) and in services around childbirth (15/27). NCEs mostly include all cases (19/23) and include adverse outcomes both during and after the initial hospital episode (17/23). The annual volume of cases varies from four to over 6000. With one exception, NCEs make no attempt to use ‘controls.’ Research evidence of the impact of the recommendations from three of the largest and longest running NCEs is poor, with no time-series analyses or experimental studies, and is restricted to considering their impact on the structure and process rather than the outcome of care.

Conclusions The lack of scientific evidence on the impact of NCEs on improving safety, combined with uncertainty as to the validity of their recommendations and their high cost, suggests the need for rigorous evaluation and a reconsideration of their contribution. One option is to nest NCEs within prospective national clinical audits.