[Screening induced by health services: impact and consequences. Ethical issues].

The main aim of screening is to identify people with an increased probability to benefit from preventive interventions, generally from secondary prevention but also from primary prevention activities. The goal is to facilitate early diagnosis and treatment in order to modify positively the prognosis (the former case), or to recognize people exposed to risk factors which increase the incidence rate of disease, and then to prevent the disease (the latter case). Good intentions are not enough to achieve good results in terms of effectiveness, safety, efficiency or equity. It is necessary to have a systematic assessment of the consequences of screening, particularly on the impact on peoples health and on the health services. Due to the diversity of types of screenings that are done, it is very difficult to estimate the net impact caused by their implementation. Moreover, the changes in the health of a population depend on many factors other than health service interventions. Thus, it is very important to determine the effectiveness and safety of the screening methods that are most frequently applied. Unfortunately, assessment of the benefits and the harm potentially caused by preventive interventions has not been done often. In Spain only a few partial assessments have been published, and they focus on the activities and the processes themselves rather than the final outcomes. Given that screening activities are carried out in health care services, and that the populations screened are mostly healthy people, the ethical issues have great importance when health policies are designed and implemented. Thus, it is recommended that screenings activities be analyzed applying the ethical principles of autonomy, benefit, safety and justice. If any screening program cannot reasonably satisfy these principles then they should be removed from the list of public health activities that are financed by public resources. In the same sense, all screening procedures offered to the population must be subjected to a systematic evaluation of their effectiveness, safety, efficiency and equity in terms of how the procedure would be applied. Lastly, to achieve an effective implementation of the principle of autonomy as well the desired goal of empowering the population to exercise some control over their determinants of health, it is recommended to explore new ways of achieving active citizen participation to establish preventive priorities and to assess the impact of screening interventions.