research tools are provided to them to complete self-report. The place of filling the questionnaire could be at work or at home, according to the wishes of the nurse. Then, in the next referral of the researcher to the research units, completed questionnaires were collected. Data analysis was performed using SPSS 11.5. Descriptive statistics were used for demographic characteristics. Also, the normal distribution of data was tested by Kolmogorov-Smirnov test. Mann-Whitney and Kruskal-Wallis tests were used to determine the relationship between legal ethical and different variables. The significance level was set This report responds to a request from patient safety researchers and research ethics committees (REC) for advice on how to interpret existing research ethics guidelines in the context of patient safety research. The report, which was produced by the WHO Patient Safety Programme and the WHO ERC Secretariat, builds on the reflections of an international expert group and was further enhanced by internal and external expert reviews by research ethics specialists and patient safety and quality improvement scientists from across the world. As explained in the foreword, this is the first version of this report, which will be revised to include future input, as evidence and scholarship in the area of patient safety research evolve. This document is not intended to establish any new ethical principles. Rather, it represents an interpretation and application of existing, internationally accepted ethical principles to specific questions that arise in the context of patient safety activities. It is designed to be useful to patient safety professionals, investigators, health-care institutions, ethics review committees, health authorities and others aiming to ensure ethical conduct of patient safety research activities. It is hoped that the document will increase the attention given to ethical issues around patient safety research around the world, but particularly in resource poor-settings, where the need for locally applicable research findings is especially needed. Ethical issues to consider when conducting patient safety research WHO estimates that tens of millions of patients worldwide suffer disabling injuries or death every year due to unsafe medical practices and care. Nearly one in ten patients is harmed due to preventable causes while receiving health care in well-funded and technologically advanced hospital settings.1 Much less is known about the burden of unsafe care in non-hospital settings, where most health-care services are delivered.2 Furthermore, there is little evidence concerning the burden of unsafe care in developing countries, where the risk of harm to patients is likely to be greater, due to limitations in infrastructure, technologies, and human resources.3 A retrospective analysis of medical records of patients admitted to 26 hospitals in eight developing and transitional countries estimated an incidence of preventable harm of almost 1 in 10.4,5 Research to understand the causes of unsafe care and to identify potential solutions involves diverse scientific designs and methodologies. For example, research may be based on a review of medical records, observations, surveys or interviews. It may use controlled randomized designs, allocating different hospitals or clinical units to alternative ways of delivering care, or it may use simulations. While patient safety studies share methodologies with many other types of health-related research, some aspects of patient safety research may appear different in ways that can have a bearing on the types and extent of ethical oversight that may be warranted.6 For example, in patient safety research, the research “subject” who is targeted with a new intervention may be a health-care provider rather than a patient, even when outcomes are based on patient-related information, or the target may be a “system” of care rather than an individual. The issues raised by such methods are analogous to those raised in research using cluster designs.7 In other studies, researchers identify errors that occurred during health-care, errors that may not have previously been known to patients or their families. Some tensions may arise between a researcher’s duty of care to an individual