There are an estimated 370 million Indigenous peoples residing in approximately 90 countries [1]. They are among the most marginalised of peoples, which has a substantial impact on their quality of life and health [2]. Many research studies have been conducted in Indigenous communities, however non-Indigenous researchers have not always addressed community priorities, nor collaborated in research with Indigenous people [3, 4]. Rather, researchers have often been perceived as doing research on, not with Indigenous people, with little regard to local cultural protocols and languages and without seeking consent from communities [3–6]. When approaching individual participants for consent to participate in research, researchers often don’t communicate in ways that can easily be understood [3–6]. Recent international guidelines for researchers working with Indigenous communities stress the need for a more culturally sensitive and collaborative approach [7–14]. By working along-side Indigenous researchers and in continuous consultation with cultural advisors, some non-Indigenous researchers working with Indigenous communities are striving to be more ethically sound and culturally conscious, however, the inequality persists [4, 15]. It should be noted that due to the diversity of the world’s Indigenous peoples [1], the United Nations has not adopted an official definition of ‘Indigenous’ [2] and in specific regions there may be a preference for other terms for example ‘Native Hawaiian’ or ‘Aboriginal’. In this paper we use the term ‘Indigenous’ when referring to these populations in the general sense and when reporting specify in publications will use the name referred to there. In this review we include publications that describe specific guidelines for working with Indigenous populations, which may not capture research in low to middle income settings where the majority of the population is considered to be Indigenous. This review also excludes reports that are not published in English.

The history of consent itself is interesting. One of the earliest proclamations for the right to consent in human experimentation was made in 1891 by the Prussian Minister of the Interior with regard to Koch’s so-called ‘remedy’ of tuberculin injections for the treatment of tuberculosis in prisoners [16]. Guidelines specified that ‘the remedy must in no case be used against the patient’s will’ [16]. An early record of an official consent form dates back to 1900, when research was conducted on to control the transmission of yellow fever from Cuba [17]. This was developed in response to popular resistance, published in Cuban newspapers, to Spanish immigrants being used as “Guinea Pigs” [17]. In 1927 Claude Bernard proclaimed that potentially harmful experiments should not be conducted on men ‘even though the results might be highly advantageous to science, i.e. to the health of others’ [18]. The Nuremberg Code was formulated in 1949 to protect against experimentation such as that conducted without consent on prisoners of World War II [19]. The term ‘informed consent’ as used today, was coined in 1957 during the landmark case of Salgo versus Leland Stanford etc. Bd Trustees [20] in the United States after a doctor failed to inform a patient of the potential risk of paralysis following a novel surgical procedure. The World Medical Association worked on setting up protecting the rights of research participants and developed the first edition of the Declaration of Helsinki published in 1964 [13]. Unethical research projects were relatively common. For instance, in 1966, Beecher’s landmark publication on ethical irregularities cited at least 22 unethical medical research projects [21]. Other research conducted in the United States that enrolled impoverished African Americans with syphilis from 1932 until 1972 failed to treat participants with penicillin, long after it was known to be a highly effective treatment [22]. Even recently, the way in which the Human Genome Diversity Project has been conducted has been questioned in places such as Australia, with concerns that there was a lack of respect for the cultural values of Indigenous people [23].

Time is rarely invested to ensure that vulnerable populations understand the information provided to them about a research study [24]. Minogue (1996) claims that modern research can be so complicated that even a fully competent individual is unable to give informed consent (as cited by [25]). Beyond consent, the issue of ownership of research findings requires consideration. With advances in biotechnology there are implications with regard to intellectual property rights, where companies are trying to patent genetic material of research participants for their commercial value [26]. The World Intellectual Property Organisation’s (WIPO) Grand Council of the Crees [27], endorsed the United Nations Declaration for the Rights of Indigenous Peoples (UNDRIP) [9], highlighting the importance of protecting the genetic resources, traditional knowledge and traditional cultural expressions of Indigenous people. Many countries supported these values but it was not until 2007 that colonised countries such as the USA, Australia, New Zealand (NZ) and Canada formally endorsed this policy, indicating that Indigenous people of these countries have been particularly vulnerable to denial of their human rights, including when it comes to participating in research and intellectual property.

In countries where ethical recruitment of participants for research requires consent forms and participant information statements to be written in “plain English”, many potential participants without English as their first language require an interpreter [28]. The interpreter faces the challenge of both explaining research jargon across a language barrier, and translating the cultural and scientific significance of the research [28]. English is often the second, third or fourth language for Indigenous people, especially in remote communities [5]. This makes it difficult for Indigenous participants to fully comprehend the “foreseeable risks” to which they are consenting [28]. Yet, even with these known challenges, Indigenous participants’ understanding of and preference for the consent process has rarely been investigated [5, 29, 30].

Our aim was to conduct a systematic review of peer-review and grey literature to identify studies and guidelines that describe specific methods used for seeking consent for research with Indigenous communities and potential individual participants. We also aimed to include studies that described and evaluated the process of seeking consent and its impact on promoting understanding of research, considering individual participant preferences and cultural beliefs.

We found few publications that describe specific communication methods for seeking informed consent for Indigenous research and even fewer that evaluate participants’ understanding or preferences for the process [4, 5, 7–14, 29, 30, 33–77]. This may be explained by publication bias or simply reflect lack of attention to the consent process in these vulnerable populations [82, 93]. As mentioned previously there are over 90 countries with Indigenous populations [1], however this review is limited to reports published in English and might also exclude research from countries in which the majority of the population may considered to be Indigenous, but have not necessarily specified that they are working with an ‘Indigenous’ population.

The only original research study evaluating the consent process, Russell et al [33] had a very small study sample, with only twenty mothers who identified as Aboriginal. Researchers identified the need for multiple presentations of information, including by local Aboriginal people, and use of visual aids to enhance participants’ understanding of the proposed research. The role participants played within the Aboriginal community and the specific communities where the participants lived were not described, but it is unlikely that this is a representative sample of Aboriginal people living in Central Australia and hence the results may not be generalizable. Bull [34] did not evaluate understanding or preferences regarding the consent process by the community or individuals, but through discussions with community leaders concluded that researchers must establish a reciprocal relationship with the community, ensure that research is relevant to that community, respect cultural protocols and involve Aboriginal people in the conduct and reporting of the research. McCabe [35] describes a research approach that was badly received by the community and provides lessons about what to avoid, including reliance on telephone communication. The need for community input into consent forms, avoidance of scientific jargon, and inclusion of graphics were recommended to increase understanding [35]. Fong [36] assumes that Hawaiians’ failure to consent to use of their biological samples for future studies related to cultural beliefs relating to desecration of body parts but did not substantiate this theory. This illustrates the need for researchers to thoroughly understand cultural beliefs and practices. Baydala [37] used a novel consent process respecting local cultural protocol when seeking consent with elders of Aboriginal communities of the Alexis Nakota Sioux Nation, Alberta, Canada, but acknowledged that this process may be inappropriate among other First Nations or Inuit communities of Canada.

In articles that describe the consent process in detail, those with high recruitment typically involved local Aboriginal organisations and leaders in the project design and recruitment [38, 42, 48]. In The Lililwan Project, researchers employed local Aboriginal people as community navigators to disseminate study information, assist with recruitment of participants and support the research team in seeking written consent from parents and carers [38]. A plain English statement and consent form was read out and interpreted in their preferred language with the assistance of pictorial aides [38]. There was 95 % participation in this study, while using this method to seek consent [48]. In NZ there is a term Kaupapa Māori Research, which encompasses the idea that research with Māori populations should be driven by Māori researchers [4, 39]. Wilson [42] emphasises the importance of researchers fostering equitable relationships with the community they are working with, however some studies we found do not appear to involve local Indigenous community members in this way [29, 30, 43]. There is often a communication gap between Indigenous and Non Indigenous communities, especially between them and researchers and health services [94]. Alison Hoy [95] raised concerns that this may result in Indigenous people being excluded from crucial projects because of the perception of exploitation. This may deny Indigenous people the opportunity of helping address major health disparities and benefiting from the results. Teams of non-Indigenous researchers often fail to acknowledge their different cultural backgrounds and philosophies on life compared to Indigenous people [96]. Indigenous and Non-Indigenous authors compare and discuss how the differences between their “two worlds” impacts on the quality of research, noting that certain attitudes to research with Indigenous communities can prevent it from being conducted in a culturally respectful way [4, 5, 34, 35, 42]. There is a language of inequality embedded even within today’s publications, with the idea that Non-Indigenous people are researchers and Indigenous people are the researched [4]. It is thus necessary for researchers to engage a community and foster relationships with leaders and local organisations [97].

A total of 38 research guidelines were included in this review, the majority of which define the term free, prior and informed consent, but few of which describe how this can be achieved. Some guidelines do not mention Indigenous communities as a special group for consideration and simply state that “language and cultural” differences must be accounted for [13, 66]. Others include special sections emphasising the vulnerability of Indigenous people with regard to research [10, 12, 14] or remind us of Indigenous Peoples rights [8, 9, 11].

Some research guidelines note the importance of seeking consent for research initially from a community leader or council of elders [5, 7, 8, 10–12, 49–51, 53, 54, 56–63, 65, 67–75, 77]. Some determine that only the community has control over what information may be publicly released [8]. The concept of community consent is debated and many questions arise regarding what comprises a community and who can represent a community [72, 98]. Tsosie [99] notes that in some communities a member may hold the duty to keep secret certain knowledge even from other community members and that this may prevent provision of consent or dissemination of results.

Of the national guidelines (n = 20), NZ appears to offer the most protection for the rights of Māori, based on the spirit of the Treaty of Waitangi and Kaupapa Māori Research [59–63]. Culturally significant language is embedded into the research guideline, which identifies that it is preferable for Māori researchers to take charge of projects that are about or may affect Māori people [59–63]. Australia and Canada also have culturally sensitive guidelines but it is difficult to translate values espoused into practice [49–58, 64, 65]. Neither of the USA guidelines specifically addressed the consent process for research with Indigenous people [66, 67]. The Tribal Epidemiology Centres report that research organisations have found it difficult to work with people who identify as American Indian or Alaskan Native due to their mobility, literacy, and language barriers [67]. Community Based Participatory Research with locally designed protocols has increased participation rates [67].

Researchers working with Indigenous people must be culturally respectful [92]; cognisant of the law [20, 26, 100]; and conscious of the impact of research on communities as a whole [101]. Ethical guidelines emphasise the need to approach Indigenous communities, governing bodies and leaders for consent prior to approaching individual participants. Best practice recommends a collaborative approach, in partnership with local Indigenous people, and research that addresses community priorities. Communication aids and involvement of local Indigenous researchers can help overcome language and cultural barriers when seeking consent [4, 5, 33–35, 38, 39, 42, 48, 65, 67].

Our literature review identified few original articles that evaluate preference or understanding of the communication methods used in seeking informed consent for research with Indigenous populations. To ensure that future research is of value to Indigenous communities, there is an urgent need for research to understand how to best seek consent.