**3. Level of dependency**

an investigation. It is essentially a condition that compromises the exercise of autonomy. The vulnerability condition is dual, which speaks of the reciprocity of actions between the investigator and the participant. Research becomes vulnerable to the extent that one of its actors

Vulnerable people have limited capacities to consent; this can be given by the absence of power of choice and decision, as in prisoners; legal capacity to consent, for example, in minors; or ability to understand, as it occurs in people with mental illness. A researcher is also vulnerable when choosing a special population. Ethical shortcomings in the recruitment process or in the same experiment can seriously compromise the generalization of the results to other populations, thus fulfilling the biostatistics conditions. In addition, the criminal and

The researcher who includes a special group has to recognize that this fact implies a greater sharpness and refinement in the devices that he uses to obtain his results, and even in the long-term follow-up of those who have been his participants. The Bioethics Committee, for its part, has to monitor and advise with particular rigor the protection of the interests of the

The Helsinki Declaration of the World Medical Association of October 2000 adds, "Medical research on human beings should be carried out only by scientifically qualified persons and under the supervision of a clinically competent physician. The responsibility of human beings must always rest with a person with medical training, and never with the participants in the research, even if they have given their consent." This warning regarding medical research serves to emphasize the need for the appropriate professional qualification of researchers as a

Often reflection on vulnerability is concentrated on the participants and the analysis of the conditions of the researchers is neglected. In recent years, proposals have been presented to ensure the ethical transparency of research projects. One of the central points in this order of ideas is the declaration of conflicts of interest. A researcher becomes a vulnerable individual when he or she does not fully state the economic, political, or other interests that may substantially compromise his or her ability to make decisions in the course of research. This is a mode of vulnerability that is just beginning to be explored "researchers must be aware and obliged to declare, not only to the Research Ethics Board, but also to the research subjects, any conflict of interest that they may have and any financial gain they expect to obtain per patient as a result of the recruitment." To this point, it is advisable to make a point the researcher, and of course his work group, can also acquire the condition of vulnerability essentially due to deficiencies in training professional

Bioethics Committees should be alert to the cautious reviews of protocols that focus exclusively on potential organic damage and do not address the likelihood of moral damage. Written registration in the consent of measures such as limits of confidentiality or the means of communication for the call and follow-up denote the interest to prevent the increase in

means of reducing the vulnerability inherent in the personnel conducting the study.

and scientific and also for the partial declaration of conflicts of interest.

vulnerability derived from participation in the study.

civil consequences that involve the fissures in the ethical structure of a research.

exhibits limitations for the full protection of personal integrity.

people linked to the investigative process.

140 Clinical Trials in Vulnerable Populations

For special and vulnerable populations, their relationship with the biomedical and psychosocial research apparatus determines another criterion for evaluating the conditions for the granting of valid informed consent.

Ethical tension is heightened when research is merged with medical care. "Intimidation, in any way that is done, invalidates informed consent. Potential subjects, who are both patients, often depend on the physician/researcher's medical care, which therefore has some credibility before their eyes, and whose influence on them can be considerable, particularly if the protocol of study has a therapeutic component. They may fear, for example, that refusal to participate would damage the therapeutic relationship or mean the omission of health services. The physician/investigator must assure them that their decision to participate will not affect the therapeutic relationship or other benefits to which they are entitled. In this situation, the ethics review committee should consider whether informed consent should be sought by a neutral third party" [1].

The type of link between the researcher and the participant can increase the vulnerability in a bidirectional way. The researcher may feel more comfortable with people who have already been approached clinically and with whom recruitment is usually easier given prior recognition. However, there are several risks such as intimidation, undue influence and even the introduction of statistical bias due to limitations in sampling, which in turn ethically compromise the study by obtaining restricted results in its generalization.

On the patient/participant front, the situation is also equally complex. People can remain in an investigation, against their personal desire, only to avoid a loss or deterioration in the therapeutic attention they are receiving "even a fully capable person may have difficulty objecting to following a project due to their dependence on the relationship medical, and the vulnerability inherent in such dependence" [2].

Additionally, it should be noted how deficiencies in assertiveness can lead to vulnerability in participants. This becomes more prominent in some Latin American populations where the figure of medical personnel is inserted in a paternalistic model of care that confers an almost absolute power in the therapeutic relationship.

Extending the concept of dependence out of the therapeutic context are similar ethical difficulties in doubles as employer/employee or teacher/student. Dependency is connected to subordination. Faced with economic difficulties or problems in academic performance, linking to a research project, even if it seems voluntary and free, may be the effect of an attempt to please the superior and obtain employment or academic opportunities. A teacher can use his charisma and academic prestige to link his students just as a doctor influences his patients.

The level of dependence marks a criterion of special populations and raises a reflection that must always be present in the formulation and revision of research protocols.
