“I want the doctors to know that I am as bright as a candle”:

Abstract

Stigma in healthcare settings is a pernicious barrier to HIV prevention and treatment in contexts with strong HIV-related structural stigma. Previous work has documented substantial stigma towards key populations and people living with HIV (PLWH) among Malaysian doctors. The perspectives of Malaysian key populations and PLWH, however, remain understudied. In 2021, 34 Malaysian participants representing key populations and PLWH engaged in a photovoice study designed to qualitatively explore their experiences with and hopes for doctor interactions. Many participants reported stigma from their doctors, perceiving that doctors view them as not normal, sinful, misguided, and incapable. Several emphasized that they wear figurative masks to conceal aspects of themselves from doctors. Yet, many also remain hopeful for constructive relationships with doctors. They want their doctors to know that they are bright, capable, kind, and valuable. Interventions are needed to address stigma among doctors working in contexts with strong structural stigma.

Introduction

HIV-related stigma in healthcare settings is a barrier to every step of the HIV care cascade, playing a fundamental role in HIV disparities globally [1]. Stigma is a social process supported by power that differentiates people based on social statuses and leads to devaluation [2]. Stigma is a multilevel phenomenon. At the structural level, it is manifested as societal-level conditions, cultural norms, and institutional policies [3, 4]. Among healthcare providers, it is manifested as prejudice (i.e., negative feelings), stereotypes (i.e., group-based beliefs) and discrimination (i.e., unfair or unjust treatment) [5]. Key populations [i.e., populations most likely to be exposed to HIV including men who have sex with men (MSM), transgender women (TGW), people who inject drugs (PWID), and female sex workers (FSW)] as well as people living with HIV (PLWH1) who anticipate and experience more stigma from healthcare providers have worse HIV prevention and treatment outcomes [1, 8–10].

Stigma is a particularly pernicious barrier to HIV prevention and treatment in places where strong structural stigma persists towards key populations and PLWH [11–16]. As examples, indicators of HIV-related structural stigma are associated with increased HIV risk among African Americans and people who inject drugs in the United States [13, 14], MSM in Europe [17], and MSM and TGW in Asia [18]. Malaysia is an example of a country where strong HIV-related structural stigma persists [19–26]. Previous work has identified substantial prejudice towards, stereotypes about, and intentions to discriminate against key populations and PLWH among Malaysian healthcare providers [27–29]. Yet, the perspectives of Malaysian key populations and PLWH on their healthcare experiences remain understudied. The current study uses photovoice to qualitatively explore Malaysian key populations’ and PLWH’s experiences with healthcare providers to inform intervention efforts to address stigma in Malaysian and other similar healthcare settings with strong structural stigma, ultimately reducing HIV disparities in these contexts.

HIV Disparities and Structural Stigma in Malaysia

Malaysia is representative of many socio-cultural contexts wherein the HIV epidemic is concentrated among members of key populations, many of whom are severely stigmatized and do not know their HIV status, have not received HIV prevention services, and/or are not receiving antiretroviral therapy. In 2020, rates of HIV among Malaysian key populations were estimated to be 15.8 to 54.0 times those of the general population [30]. Yet, members of key populations were, at best, half as likely as members of the general population to know their HIV status [30]. Many members of key populations were not reached by HIV prevention programs, with as little as 1.4% of PWID receiving prevention programming [30]. Moreover, antiretroviral therapy coverage for key populations was below the UNAIDS goal of 90% (ranging 34.6–62.6% where data are available) [30]. These HIV disparities occur within a social environment characterized by substantial stigma towards key populations.

Like many countries worldwide, stigma towards key populations in Malaysia has deep historical roots and is currently structurally sanctioned [19, 24–26]. The British Empire spread legal codes to its colonies, including Malaysia, that criminalized same-sex sexual practices with punishments including fines and lengthy imprisonment. As of 2020, Malaysia was one of 67 countries that continues to criminalize consensual same-sex conduct [19]. Secular and Shariah laws criminalize the gender expression of transgender individuals, and Shariah law prohibits gender-affirming surgery among Muslims [20, 26]. Additionally, although government officials have recently announced plans to decriminalize drug use to better address addiction, Malaysia has harsh penalties for drug possession (e.g., death penalty) [21, 24]. Laws prohibit activities related to sex work, and FSW report being charged for sex-work related crimes on the basis of carrying condoms [22–24]. These laws contribute to a social environment characterized by profound stigma towards key populations and PLWH, including within healthcare settings.

Stigma in Malaysian Healthcare Settings

Previous work has documented substantial prejudice towards, stereotypes about, and intentions to discriminate against members of key populations and PLWH among practicing doctors and medical students in Malaysia [27–29]. For example, medical students report explicit negative feelings towards MSM and PWID, and ambivalence towards PLWH [27]. Medical students who are Muslim and Malay tend to endorse greater prejudice towards key populations than those of other religions and ethnicities [27, 31]. Moreover, doctors and medical students who endorse greater prejudice toward and fear of key populations and PLWH also report greater intentions to discriminate against these patients [28, 29, 31]. This work additionally suggests that prejudice towards key populations and PLWH is correlated such that individuals who endorse more prejudice towards one key population or PLWH group also endorse more prejudice towards other groups [28]. Less work has been conducted to explore the perceptions and experiences of key populations and PLWH in Malaysian healthcare settings.

The current study explores Malaysian key populations’ and PLWH’s experiences with doctor interactions. It focuses on meta-perceptions, which are thoughts about how others see the self [32]. Meta-perceptions play a powerful role in shaping the extent to which individuals anticipate stigma from others. Key populations and PLWH who believe that healthcare providers feel prejudice towards and believe stereotypes about them may anticipate stigma from those providers. In turn, key populations who anticipate stigma from healthcare providers are less likely to access HIV testing and pre-exposure prophylaxis (PrEP), and PLWH who anticipate stigma from healthcare providers are less likely to access HIV care [1, 8–10]. The current study additionally explores Malaysian key populations’ and PLWH’s hopes for provider interactions, with a focus on what they would like providers to know about them. Greater understanding of key populations’ and PLWH’s experiences with and hopes for doctor interactions can inform interventions to reduce stigma in healthcare settings and close HIV disparities in Malaysia. These findings may also be useful in other environments characterized by substantial stigma.

Methods

Procedure

Members of key populations and PLWH in Malaysia engaged in an online photovoice project in the fall of 2021. Photovoice, a qualitative method involving photography and story-telling [33], was chosen as a research method because it yields rich data and allows for creative expression among participants. Moreover, online, asynchronous photovoice methods offer high levels of confidentiality for participants who do not have to speak with members of the study team or travel to a data collection site.

The photovoice project was facilitated by a website, with content available in both Bahasa Malay and English. The first page of the website included a video that introduced participants to the photovoice project. The doctor in the video noted that doctors providing HIV prevention and treatment services may struggle to understand the lives of their patients who have used drugs, sexual and gender minorities, sex workers, and PLWH. The doctor explained that the goal of the study is to help doctors connect with and better understand the experiences of their patients so that they can provide better HIV-related care. After watching the introductory video, participants viewed an informed consent form and indicated their agreement to participate. After providing consent, participants could watch a series of instructional videos about photography. These videos were created for the current study and featured a professional photographer and professor of photography.

Lastly, participants were introduced to the photovoice prompts. These prompts included: (1) what makes you happy? (2) what makes you sad? (3) what is important to you? (4) what challenges do you face? (5) how do doctors see you? and (6) what do you want doctors to know about you? Each prompt was accompanied by a video featuring doctors explaining why knowing the answer to the question would help them provide better care, as well as an example of a photovoice response. To respond to the prompt, participants were invited to submit a photograph and caption via the website. A member of the research team was available to answer participant questions about the study. All participants responded to all of the study prompts, and received monetary compensation for their time. All procedures were approved by institutional review boards at the Universities of Malaya and Delaware. For more information about the study website and procedures, please see Earnshaw et al. [34].

Participants

Participants were recruited in partnership with local community-based organizations that serve key populations and PLWH. Digital flyers in Bahasa Malay and English were shared via social media and WhatsApp. The study was advertised as “Photovoices in Healthcare: Connecting through Photography” and participants were told that they would be asked to answer questions about their experiences with doctors. Individuals were eligible to participate if they were 18 years or older, had access to a camera phone with internet connection, and belonged to a key population group or were living with HIV. The recruitment materials directed individuals to contact the study research assistant, who screened individuals for study eligibility via WhatsApp.

In total, 34 individuals participated including 12 (35.3%) MSM, 8 (23.5%) PLWH, 7 (20.6%) TGW, 7 (20.6%) FSW, and 6 (17.6%) PWID. Five (14.7%) individuals identified as MSM and PLWH, and one individual (2.9%) identified as TGW and PLWH. Half completed the project in Malay and half completed it in English. Over half of participants identifying as MSM (66.7%), TGW (71.4%), and PLWH (62.5%) responded in English whereas over half of participants identifying as FSW (71.4%) and PWID (83.3%) responded in Malay. To best protect participants’ identities and encourage trust in the project, socio-demographic data that could be used to identify participants (e.g., age, gender, ethnicity, religion) were not collected.

Analysis

The current analysis focuses on participant responses to the prompts “how do doctors see you?” and “what do you want doctors to know about you?”. Rapid Qualitative Inquiry methods were employed to analyze the data [35]. Malay captions were first translated to English by two members of the study team. We then took an iterative and team-based approach to data analyses. Initial findings based on photographs and captions were summarized and examples of findings were identified by three members of the study team, including two Malaysian and one U.S. team members. Themes were compiled as they emerged from the data. Next, findings were discussed with members of the full team, which included Malaysian and U.S. researchers and clinicians. This discussion focused on reaching consensus about findings and included identifying new questions about the data. Findings were then re-summarized by the three members of the team who led the initial summary and then re-discussed by the full team, and conclusions were refined. As a trustworthiness check, results were then shared with members of the project’s Scientific and Community Advisory Board belonging to key population groups to verify the team’s conclusions.

Results

“How do doctors see you?”: Participants’ Meta-Perceptions

In response to the question “how do doctors see you?” participants reported that doctors’ perceptions of them ranged from positive to negative. Several participants noted that doctors view them positively and want the best for them. A PWID participant responding in English whose photograph featured objects and a setting that promotes physical and emotional wellbeing (i.e., sunscreen, apple, stuffed animal, glasses, and pool) reported that doctors perceive them to be resilient and encourage them to be healthy. They stated:

The doctors see me as someone who is brave and strong being able to go through life despite having problems with my health, but they also see that I need to give a lot more attention and love on myself so that I can stay as healthy as possible. Other than that they also said to avoid thinking about things that upset me cause it really effect my physical.

Similarly, a MSM participant responding in English whose photograph featured yellow flowers bathed in sunlight noted that doctors view them as a bright flower who is capable of taking care of themselves. Other participants noted that doctors’ views of them were kind and professional (e.g., “very satisfactory, kind and professional” [TGW participant responding in Malay]) as well as understanding and non-judgmental. As shown in Fig. 1 A, a FSW participant responding in Malay whose photograph featured a beautiful, expensive dress on a dress form noted that their doctor treats them like a human being.

Fig. 1.

How do doctors see you?

In contrast, many participants characterized doctors’ perceptions of them as stigmatizing. A PWID participant responding in Malay noted that “there are a number of unprofessional doctors, too much stigma, double standards” and a MSM participant responding in English reported that “they judge and stereotype me without treating (me) as an individual.” As shown in Fig. 1B, another MSM participant responding in English reported that they feel that doctors see them as not normal and shocking, including during HIV testing visits. Their photograph featured feet with painted toenails, suggestive of gender transgression. A TGW participant responding in English whose photograph featured a branch on the ground noted:

Even though, I’m a transwomen but my ID card identify myself as man so most of healthcare workers see me as man. This is not what I want or identify. I just hope I could be the branch from the picture which is genderless.

Another TGW participant responding in English noted that “doctors see me as someone who committed sin, and I should repent and be as I should be (a man).” Participants reported that these stigmatizing perceptions resulted in doctors judging them as incapable of taking care of themselves. A MSM participant responding in English captioned their photograph featuring a withered purple flower: “Small. Misguided. Helpless. Even when I do have the medical expertise, it’s not enough to convince them that I am capable of understanding my body and my limits. To them I am withered flower in need of caring.” Participants additionally questioned whether doctors care about them. One PLWH participant responding in Malay whose photograph featured HIV medications stated: “I always doubt whether a doctor was really sincere in treating me or just fulfilling his duty.”

Participants also responded to the question by emphasizing that they conceal parts of themselves, or wear a figurative mask, in healthcare settings. Some participants reported that doctors are aware of the concealment, and may even see their true self. A FSW participant responding in English noted that doctors see them as “Look good and bold outside but afraid to open up. I keep it low key and my doctor see that in me.” Their photograph featured the outer petals of a bright pink flower, the interior of which is hidden from view. A MSM participant responding in Malay whose photograph included pushpins with bright, round plastic heads noted that they are like the pins: “the first side is round where I will face (doctors) and share what I go through voluntarily and transparently, and the next side is sharp where I try to hide from them.” Other participants suggested that doctors are either unaware that they are concealing or do not see the real them. As shown in Fig. 1 C, a MSM and PLWH participant responding in English noted that they mostly hide who they are from others due to distrust, sharing a calm and “sugarcoated” exterior with doctors. Their photograph featured a calm landscape of trees that is zoomed out, emphasizing distance.

“What do you want doctors to know about you?”: Participants’ Hopes for Doctors

Participant responses to the question “what do you want doctors to know about you?” emphasized their humanity and desire to be seen and treated equally to other patients. Many participants responded that they wanted to be known by doctors as unique, kind, or valuable in some way. As shown in Fig. 2 A, a MSM participant responding in English whose photograph featured a candle noted that they wanted their doctors to know that they are intelligent, capable, and bright. Similarly, a FSW participant responding in English whose photograph featured a doll collection shared that “despite the challenges and trials I go through every day, I am a cheerful and childlike person.” Some participants emphasized their value or worth. A PWID participant responding in Malay whose photograph featured a leafy plant noted that “I want the doctors to know that I want to be like a leaf, even though it is unattractive, there are still some benefits where it can shade us, and when it falls, it is still useful as fertilizer.” Other participants emphasized that they are normal, or like other patients. A PLWH participant responding in Malay whose photograph featured a group of goats noted that “I want the doctor to see me the same as any other patient without any difference in terms of the type of disease or otherwise.”

Fig. 2.

What do you want doctors to know about you?

Several participants wanted doctors to see and treat them without stigma or discrimination. As shown in Fig. 2B, a TGW participant responding in English whose photograph featured horses in a forest noted that she wants to be seen equally to other patients, without stigma or discrimination. Other participants called on doctors to treat them without judgment. For example, a PWID participant responding in Malay whose photograph featured a white cake artfully topped with strawberries noted that they wanted doctors to “easily and calmly accept what is presented without seeing and judging the individual that prepares it.” Another PWID participant responding in Malay whose photograph featured a hand holding a vertical bar, reminiscent of a jail cell, stated “I hope the doctors see me as someone who dares to come out of the existing cocoon. Don’t get caught up in the insults that are offensive and demeaning.” A MSM participant responding in English whose photograph featured a single, bright purple flower emphasized that they wanted to be treated as an individual based on their life circumstances rather than their risk group membership. They stated: “I want the doctors to know that I may be bisexual but my orientation doesn’t make me a high risk behaviour client. Treat me as an individual based on my story/history without prejudice to my sexuality.”

Participants also wanted doctors to see beyond the figurative masks they wore in healthcare settings and recognize the vulnerability or pain underneath. They addressed their needs related to HIV, including challenges surrounding HIV risk, fear of HIV testing, and concerns related to living with HIV. A FSW participant responding in Malay whose photograph featured the sky seen through a broken roof stated: “Support. I want doctors to know about me that I am often a place of refuge for others but that I also need protection. I sometimes fail to protect myself from my negative and unhealthy environment.” A TGW participant responding in English whose photograph featured HIV and STI tests noted: “I am very apprehensive about doing the HIV screening. Malaysian in general are still lack of information regarding HIV/AIDS which lead to Stigma and Discrimination.” A MSM and PLWH participant responding in Malay whose photograph featured pelicans with their wings spread defensively stated that

I want the doctor to know about me that I am strong but there are times when I get scared when I face the limitation of this disease where I need the support of medical knowledge in terms of facts and moral support.

Finally, many participants appealed to doctors for help and support. Some requested help to be healthy. A FSW participant responding in Malay whose photograph featured a rice paddy landscape noted “As healthy as paddy is to produce rice, please serve us so that we are healthy.” Others called for guidance. A MSM and PLWH participant responding in English whose photograph featured the reflection of a sun setting over the ocean noted:

In between light and shadow there’s a reflection of who we are. Guide us so that when light and shadow meet, only ourselves remain. Guide us on a better path so that one day we can stand on our own or even help people like us.

Several participants asked for emotional support. As shown in Fig. 2 C, a PWID participant responding in Malay whose photograph featured two hands holding each other noted that they need moral support from doctors to develop self-esteem. As shown in Fig. 2D, one MSM participant responding in English whose photograph featured the back of a person reaching towards the sky and wearing angel wings noted that they wanted freedom to be themselves around a doctor who will tend to their wings rather than clip them.

Discussion

Results of this study provide insight into the experiences of key populations and PLWH in Malaysian healthcare settings. Like many other countries with persistent HIV disparities, Malaysia is a context characterized by pronounced HIV-related structural stigma. Previous work has found that Malaysian doctors hold prejudice towards, stereotypes about, and intend to discriminate against key populations and PLWH [27–29, 31]. The current study confirms that key populations and PLWH perceive stigma from their doctors. As examples, participants perceive that their doctors view them as not normal, sinful, small, misguided, helpless, incapable, and withered. Several emphasized that they wear a figurative mask in healthcare settings, concealing and protecting aspects of themselves from their doctors. Their photographs exude distance (e.g., zoomed out landscape) and defensiveness (e.g., sharp pushpins). These perceptions extend to HIV prevention and treatment care visits, with key populations perceiving that their doctors view them as shocking during HIV testing visits and PLWH questioning whether their HIV doctors sincerely care about them. These findings are consistent with research from other global settings with strong HIV-related structural stigma (e.g., countries that criminalize same-sex practices), wherein key populations and PLWH report experiencing stigma in healthcare settings [36–38] and disparities in HIV services persist [39, 40].

Participants also reported positive perceptions and experiences, many of which are compatible with the values of patient-centered care [41]. In patient-centered relationships, patients are understood by doctors as people in the context of their social environments and are respected, informed, and listened to [41]. Consistent with these values, participants noted that their doctors see them as strong, brave, and capable. They emphasized that their doctors are non-judgmental and understanding. Some of the participants’ photographs referencing their doctors featured objects and settings that promote health behaviors and wellbeing (e.g., sunscreen, apple). Results of the current study additionally suggest that key populations and PLWH who have had negative experiences in healthcare settings may remain open to and hopeful for positive and patient-centered relationships with their doctors. As examples, participants reported that they want their doctors to know that they are intelligent, capable, bright, cheerful, kind, giving, unique, normal, and valuable. The desire to feel human and valuable stands in sharp contrast to the dehumanization and devaluation inherent to stigma processes [2]. Several participants reported wanting to take off their masks within healthcare settings to share their vulnerability and pain with their doctors. They also desired support and guidance from their doctors, or to be cared for. Participants’ photographs evoked cooperation (e.g., holding hands) and freedom (e.g., wings). Ensuring that patients are empowered to be involved in their care is an additional key component of patient-centered care [41].

There were many similarities and some key differences in responses among participants identifying with various key population groups and responding in Malay versus English. The main themes identified in this study, including perceived stigma from doctors and hopes for positive relationships with doctors, were observed among participants belonging to all key population and language groups. Yet, there were also several key nuances in their responses. For example, although participants belonging to most key population groups described masking in healthcare settings, TGW participants did not. TGW in Malaysia may be less able to conceal their gender identity in healthcare settings if the sex on their ID cards does not match their gender expression. Additionally, several MSM participants’ responses emphasized their individuality and several FSW participants’ responses called attention to harmful social environments. These findings underscore the importance of incorporating an intersectional stigma lens when researching and intervening in stigma experienced by key populations and PLWH [42]. This lens encourages researchers and interventionists to seek to understand and address both shared and unique experiences of stigma among communities affected by HIV.

Strengths, Limitations and Future Directions

This program of research is focused on addressing HIV-related stigma as a barrier to HIV prevention and treatment in Malaysia. This study therefore included participants from multiple key population groups, including MSM, TGW, FSW, and PWID, as well as PLWH. Previous work suggests that Malaysian doctors endorse stigma towards all of these groups [27]. As noted above, results of the current study suggest that participants of all key population groups and PLWH perceive stigma from and hope for positive interactions with doctors. Yet, there were some key differences in the responses of individuals belonging to different key population groups. More work employing diverse methods and larger sample sizes is needed to understand variations in experiences with, perceptions of, and hopes for doctor interactions between individuals belonging to different key population, language, ethnic, gender, and other groups. Such work can inform efforts to tailor intervention strategies to the unique needs of individual patients.

This study employed photovoice, which yielded rich qualitative data and provided some insights that may not have emerged through other methods (e.g., images of landscapes exuded distance or of sharp pushpins that exuded defensiveness). Yet, other methods, such as quantitative surveys collected from larger samples and with representative sampling strategies, may be useful for characterizing the extent to which key populations and PLWH experience negative interactions in healthcare settings or understanding the outcomes of these negative interactions. Moreover, mixed-methods that blend photovoice with quantitative methods may enrich analyses by enabling interpretation of photovoice results alongside quantitative indicators of engagement in healthcare settings and experiences with doctors. This photovoice project was conducted online due to the COVID-19 pandemic. Online, asynchronous methods may have promoted participation among individuals concerned with disclosure given that they did not need to come to a specific location for a study engaging key populations or PLWH. Yet, online, asynchronous methods made some aspects of traditional photovoice projects difficult, such as group discussion and participatory analysis of photographs and captions [33, 43, 44]. Future work should seek ways to incorporate participatory analysis (e.g., via online discussion) to ensure that findings reflect participants’ experiences. Strategies for incorporating participatory analysis in future online, asynchronous photovoice projects are further discussed in Earnshaw et al. [34]

This study was conducted in Malaysia, a country with persistent HIV disparities and strong structural stigma towards key populations. Research in such contexts is critical for developing interventions to support some of the most vulnerable key populations and PLWH globally. Yet, generalizability of findings may be limited to similar socio-cultural settings. More work is needed to understand the extent to which the current findings generalize to other settings, including those with strong structural stigma towards key populations and PLWH such as the United States and Europe [13, 14, 16].

Conclusion

Key populations and PLWH in Malaysia report that many of their doctors hold negative, stigmatizing perceptions of them. As a result, some wear protective masks in healthcare settings to conceal their lives and struggles. Yet, key populations and PLWH also report wanting to take off their masks, to be vulnerable with their doctors, and hope for the opportunity to receive support and care from their doctors. It is critical to build safe and welcoming healthcare environments where key populations and PLWH can be open about themselves and receive support and care from all doctors. To achieve this, multi-level interventions are needed to address stigma in healthcare settings in Malaysia and similar contexts [1, 45]. Such interventions should implement evidence-based stigma intervention tools at the institutional level (e.g., change policies, redress systems, restructure facilities) and individual healthcare provider level (e.g., enhance knowledge, build skills, facilitate contact) [1]. Photovoice projects hold promise for reducing stigma at the individual level by facilitating extended contact between members of key populations and PLWH with healthcare providers. For example, results of a randomized controlled trial demonstrated that healthcare providers who attended a performance featuring photovoice presentations from individuals in recovery from substance use disorders endorsed fewer stereotypes, less prejudice, and less support for discrimination than providers in the control condition [46]. Future research may seek to identify best practices for leveraging photovoice for stigma reduction. Finally, social change efforts are crucial for eradicating stigma at the structural level and achieving health equity for key populations and PLWH globally.

Authors’ contributions

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Valerie Earnshaw, Jon Cox, Wong Pui Li, Rumana Saifi, Suzan Walters, and Asfarina Binti Amir Hassan. All authors read, revised, and approved the final manuscript.

Funding

This work was supported by the National Institute of Mental Health (R34MH124390) and National Institute on Drug Abuse (K01DA053159). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Availability of data and material

Data may be available from the corresponding author upon request.

Declarations

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The study received institutional review board approval from the University of Delaware (1588354) and University of Malaya Medical Centre.

Consent to participate

All participants provided informed consent.

Consent for publication

In addition to consenting to the study, participants consented to have their photographs shared via publication.

Conflict of interest

The authors declare no conflicts of interest.