Healthcare interactions and barriers to chronic pain management: A qualitative study of people who use drugs in Uyo, Nigeria

Abstract The literature on chronic pain management for people who use drugs (PWUD) is suffused with research from western societies. Comparatively, less is known about the experiences of PWUD in Africa. In this study, we explore healthcare interactions and barriers to pain management for PWUD in Nigeria. We used qualitative data from in-depth, individual interviews with 26 PWUD recruited through snowball sampling in Uyo, Nigeria. Data were analysed thematically, and cultural health capital and structural vulnerability were used as theoretical lenses to interpret the findings. We found that chronic pain was seen as an intractable condition that had adverse effects on work, livelihoods, daily functioning and social relationships. Some participants experienced positive interactions with healthcare providers partly due to verbal and interactional skills. Others were subjected to stigma and discrimination due to lack of such competencies. Participants faced social and structural barriers to biomedical services, including cost, discriminatory prescribing practices, and structural and everyday stigma that made them feel underserving of services. The findings demonstrate the usefulness of cultural health capital and structural vulnerability for understanding inadequate pain management and health inequality affecting PWUD. Combining structural interventions (stigma reduction, culturally safe healthcare, poverty alleviation) with biomedical services could improve pain management for PWUD.


Introduction
Chronic pain, which is pain that lasts beyond three months, is a significant global health problem. An estimated 30% of the world's population suffer from chronic pain (Cohen et al., 2021). Estimates for Europe and North America indicate chronic pain prevalence of 20-30% (Yong et al., 2022;Zimmer et al., 2020), with an even higher prevalence in other regions of the world such as Africa (Morris et al., 2018). Chronic pain is unequally distributed between groups. Individuals of low socio-economic status often bear a disproportionate burden (Janevic et al., 2017). Socially marginalized groups (such as sex workers and people who use drugs [PWUD]) are at greater risk of suffering chronic pain due to trauma, violence, homelessness and drug use (Allen et al., 2015;E. E. Nelson, 2022). They are also more likely to face challenges in accessing pain diagnosis and treatment (Dassieu et al., 2019).
Chronic pain impairs daily functioning, compromises economic activities and results in overall decline in quality of life (Toye et al., 2013). Chronic pain is associated with comorbidities such as depression and anxiety disorders, and patients are at a greater risk of suicide than those without chronic pain (Cragg et al., 2018;Tang & Crane, 2006). Chronic pain has negative effects on the social lives and identities of patients (Glenton, 2003;Lillrank, 2003;Zajacova et al., 2021), contributing to "biographical disruption", which is the cumulative negative effects of chronic conditions on social identity and everyday life (Bury, 1982). Chronic pain patients use more healthcare services than those without the condition, and also incur higher medical cost overall (Hogan et al., 2016).
Undertreatment of chronic pain is common, and patients have reported "feeling disrespected and distrusted, suspected of drug-seeking, and having their symptoms dismissed as trivial and/or not warranting medical care" (Upshur et al., 2010(Upshur et al., , 1791. PWUD with chronic pain face significant barriers to pain management, including denial of opioid medications due to the stigma of drug addiction and being made to feel unworthy of care (Dassieu et al., 2020;Voon et al., 2018). Such experiences breed mutual mistrust between PWUD and healthcare providers (Merrill et al., 2002). In North America, chronic pain treatment intersects with the opioid overdose crisis. Current medical guidelines encourage physicians to be cautious in prescribing opioids to chronic pain patients (Busse et al., 2017). In Africa, pain management and palliative care are challenging due to national and regional efforts to prevent the misuse of opioid medications (Klein et al., 2020;E. U. Nelson et al., 2023).
Studies have explored how poverty and social marginalization affects the management of chronic conditions among PWUD. Dassieu and colleagues have shown how social deprivation exacerbates PWUD's vulnerability to chronic pain as well as foster reliance on illegal drugs to manage pain amidst structural impediments to healthcare services (Dassieu et al., 2020; see also Boucher et al., 2022). Webster and colleagues described how poverty and marginalization, mental health problems and substance use complicates pain management and contributes to inequitable work burden and exhaustion among health professionals (Webster et al., 2019). This developing body of literature consists mostly of research from North America. Less is known about how conditions of poverty and marginalization affects chronic pain experiences and management among PWUD in Africa. The dearth of local evidence has hampered the development of policies. This study aims to contribute to the literature by exploring healthcare interactions and barriers to chronic pain management among PWUD in a Nigerian city.

Chronic pain and healthcare services in Nigeria
Chronic pain is a major public health problem in Nigeria, and its management imposes a significant burden on the healthcare system. The 2008 World Mental Health Survey reported that approximately 30% of Nigerians aged 18 years and older had chronic pain (Tsang et al., 2008). Studies have reported high prevalence of chronic pain among different groups ranging from 50% among secondary school students in the south-west (Adegoke et al., 2015), to 62% among fishermen in the south-south geopolitical zone (Dienye et al., 2016), and 73.5% among professional drivers in the north-west (Rufa'i et al., 2015). Chronic pain is associated with mood and anxiety disorders and functional disability Igwesi-Chibode et al., 2018). It is exacerbated by local health practices, adverse living and working conditions, high levels of poverty, and limited access to healthcare services (Igwesi-Chbode et al., 2018).
The management of chronic pain is a persistent challenge. Studies have reported infrequent assessment, poor diagnosis and inadequate treatment of pain in Nigerian hospitals (Faponle et al., 2001;Kolawole & Fawole, 2003). Recent studies have reported stigma and discrimination perpetrated by healthcare providers against PWUD, including suspicions of drug-seeking and shaming on account of physical appearance (E. E. Nelson, 2022;E. E. Nelson & Alichie, 2022). Current restrictions on opioid dispensing imposed by the Nigerian state in response to increased non-medical use of tramadol and other prescription opioids has led to reluctance to prescribe opioids for chronic pain patients, contributing to undertreatment of chronic pain for PWUD (E. E. Nelson, 2022). Selfmedication with illegal drugs and diverted pharmaceutical drugs due to denial of prescription opioids has also been reported among PWUD (E. E. Nelson, 2022).
In Nigeria, inadequacies of the healthcare system, including overcrowding of public health facilities, staff shortage, unreliable transportation and road infrastructures, catastrophic health service cost and socio-cultural factors pose as barriers to healthcare services, which disproportionately affects the poor and marginalized (Anyebe et al., 2021;Keya et al., 2018;Onah, Govender, & Molyneux, 2014). Also, government funding for health services has been low. In 2018, only 4% of the federal budget was allocated to health (below the 15% commitment in the 2005 Abuja Declaration). Health services are mostly financed through out-of-pocket expenses (65% of total health expenditures), resulting in inequitable access to health services for the poor (Odunyemi, 2021). The National Health Insurance Scheme (NHIS), adopted in 2005 to achieve universal health coverage, covers about 4% of Nigerians and mostly those employed in the formal sector (Olaniyan & Oburota, 2019). This has resulted in the exclusion of poor and vulnerable groups. As we demonstrate in this study, these structural barriers have critical implications for biomedical pain management for PWUD.

Theoretical framing
This study explores dynamics at the inter-personal (or social) and structural levels. These are everyday interactions between PWUD and healthcare providers, and structural barriers to biomedical pain management respectively. We draw on cultural health capital (CHC) to explain healthcare interactions between PWUD and providers. CHC provides conceptual tools for understanding the impacts of culture and social status on healthcare interactions (Shim, 2010). It refers to a set of cognitive, behavioural, and socio-cultural resources such as biomedical information, communication and interactional skills, self-discipline, and risk reduction. These resources enable patients to present themselves in ways that optimize their relationships with health professionals and the care they receive (Shim, 2010). The accumulation and deployment of CHC produces advantage, and increases inequality in healthcare access between those who possess CHC and those who do not. In this study, we demonstrate how the presence or absence of interactional abilities and selfdiscipline influenced healthcare interactions between PWUD and healthcare providers.
Apart from patient-provider interactions, health service access is also shaped by inequalities rooted in social structures and institutional arrangements. To account for the implications of wider socio-economic inequalities on utilization of pain management we call on the theoretical construct of "structural vulnerability". Structural vulnerability refers to a situation of being at risk of ill-health or poor access to diagnosis and treatment due to one's disadvantaged position in society's hierarchy (Quesada et al., 2011). As Quesada et al. (2011) observed, structural vulnerability is a positionality. It is individuals' position in a hierarchical social order that makes them vulnerable to negative healthcare interactions and inadequate pain diagnosis and treatment. This includes the interface of their personal attributes (e.g., appearance, affect and cognitive status) with cultural values and institutional structures (Quesada et al., 2011). In this study, we use this concept to explain how PWUD are vulnerable to inadequate biomedical pain management due to poor socio-economic status (seen in lack of funds to bear medical service cost) and provider stigma linked to substance use. We also show how these socioeconomic factors combine with institutional policies and practices to create barriers to pain management for PWUD.

Study design and objectives
This study investigated the social and structural barriers to chronic pain management for PWUD. An exploratory design was adopted since chronic pain management is a developing field of research, especially in Africa. Snowballing was used to recruit participants and qualitative methods of data collection and analysis to explore the participants' chronic pain and health-seeking experiences. Data collection took place between June and July 2022.

Study setting
The study was conducted in Uyo, a densely populated city in Akwa Ibom state, Nigeria. The city has a land area of 188.035 km 2 and an estimated population of 1,294,726 people (World Bank, 2020). Population growth and urban expansion have outstripped infrastructures and amenities such as healthcare, housing, electricity, water and sanitation, and transportation. Commerce, services and administrative jobs mostly in the civil service are the engine of the local economy. A large proportion of the population (51%) lives in extreme poverty (National Bureau of Statistics, 2010), defined as living on less than one dollar per day. Most earn a precarious living from a poorly regulated informal sector. In regards to healthcare, biomedicine coexists with indigenous practices, including ethnomedicine and faith healing. Health-seekers often utilize these healthcare options concurrently (Izugbara et al., 2005). There are about 48 government-owned health facilities in the state. Factors such as cost, distance to health facilities, poor transportation infrastructures, negative attitudes of health workers towards poor patients, and local health beliefs impede utilization of services (Asuquo et al., 2000;Okeibunor et al., 2007).

Participants and recruitment
Eligible participants were current PWUD (using an illegal drug at least once in the past 30 days) with chronic pain. A purposive sample (n = 26, 21 males and 5 females) was obtained through snowball sampling, a procedure where the participants are asked to identify others who meet the inclusion criteria and those individuals are also asked for further recommendations (Noy, 2008). The first author used contacts from previous research to recruit the first four participants from different networks and locations to make the sample more diverse. These initial participants initiated a referral process for the recruitment of others. Participants were aged 21 to 44 years (mean = 32 years). It was difficult to recruit more female participants due to stigmatization of women's drug use (E. E. Nelson, 2021). Most participants were unmarried and had secondary-level education (see Table 1). A few were employed in the formal sector in lower-cadre, low-wage jobs. Others were engaged in informal income generating activities. All participants had chronic pain identified by the anatomical location of symptoms, the most common being chest pain. They used different types of drugs, including cocaine, alcohol, and tobacco.

Interviews
Data were collected through in-depth individual interviews with a semi-structured guide containing open-ended questions that allowed participants to elaborate on their responses. The flexible nature of the interviews made it possible to inductively explore emerging themes throughout the research process. Some of the questions contained in the guide, which are of relevance to the present analysis, are: "Did you experience any pain that lasted up to three months or more?", "how did the pain affect your daily life?", "Did you seek professional health services for the pain?", "what were the challenges you faced in getting these services?". Interviews were conducted by the first author at places that were suitable for each participant, including bars, an NGO office, and a drop-in centre for PWUD. The rationale was to maximize comfort and safety for the participants during interviews, and overall to improve the quality of the data. Interviews lasted between 35 and 60 minutes. All participants were provided adequate information about the research, assured of data anonymity and confidentiality. They all gave verbal consent before they were interviewed, including for the audio-recording of responses. They were reimbursed N500 (US$1.20) for time and transportation. Ethics approval was from the Health Research Ethics Committee of the University of Uyo Teaching Hospital, Akwa Ibom State, Nigeria.

Data analysis
Interviews were transcribed verbatim from digital audio-recorders and the transcripts were checked against the recorded versions to ensure accuracy. We coded the data based on prior themes contained in the interview guide and inductive codes generated through immersion in the transcripts. Data coding was done manually by developing codes directly from the data based on key words and concepts in the accounts (Linneberg & Korsgaard, 2019). This approach was adopted to enhance familiarity with the data and to improve analytic rigour and transparency (Gioia et al., 2013). After coding was completed, we searched for and identified themes in the data (e.g., "chronic pain as suffering", "chronic pain as disruption", "care provider stigma", "barriers to care") (see Table 2). Next, we reviewed the themes that had been identified and, in the process, coded data that were not suited for particular themes were moved to more appropriate themes or new ones were created for them. We then refined and named the themes ("chronic pain experiences", "impact of chronic pain", "healthcare interactions", "barriers to care"), and recorded the patterns of meaning in them. This approach to data coding and development of themes improved trustworthiness and reflexivity (Shenton, 2004). Further, three participants were asked to check the analysis and assess narrative accuracy and interpretive validity. They each felt that the analysis captured their intended meanings. Pseudonyms are used to identify quotes.

Chronic pain experiences
The participants offered rich narratives of their experiences of chronic pain that captured its severity and the impacts on their lives. Chronic pain was portrayed in most accounts as a persistent cause of suffering in everyday life. Some participants described how pain, though located in one area, had effects that reverberated throughout their body. For example, David (aged 36) told us: There is how it was that it was shaking me. That is, when I hold something my hands will be shaking. Even in my eyes too, I will look at things but I will not be able to see things from far distance. I will feel like one side of my chest is blocked. Like I can't breathe well. If I want to run, I can't run fast or very far. I will feel tired.
Accounts indicated that apart from being chronic, pain was also often severe. Severe pains, especially those felt in the chest, were frequently associated with coughing and spitting of blood. John (aged 26), for example, offered the following description of his chest pain: I usually have pain in my chest. Very severe. That is why I went for test and found out . . . I told them (healthcare providers) that when I cough I usually spit-out blood heavily. They prescribed the drugs that I am supposed to be taking for me, which I have been taking. That is the pain that me I have. It is in the chest.
Another participant described a form of chest pain that defied the pain medications that were prescribed for him at the hospital. This experience prompted him to conclude that biomedicine

Sub-themes
Chronic pain experiences "Everyday suffering", "Severe pain", "Protracted/ recurrent pain" Impact of chronic pain "Work/livelihoods", "Work performance", "Daily activities", "Social relationships" Healthcare interactions "Provider support", "Drug use disclosure", "Stigma/ discrimination" Barriers to care "Lack of funds", "Discriminatory insurance policy", "Self-management of pain", "Denial of medications", "Drug use stigma" does not have a cure for chronic pain. His account corroborates the view of chronic pain as an intractable condition (Zajacova et al., 2021). In his words: I have had experience of pain that lasted up to three months. When I had that pain, I went to the teaching hospital. The pain was in the chest. They gave me drugs to be taking, but the drugs could not cure the pain. They only relieved it for a while. So, the thing lingered like that and will resurface from time to time. When it happens like that I will go to the hospital. I found out that hospital treatment does not cure chronic pain. (Sylvester, aged 36) Similarly, another participant (Ini-Obong, aged 41), who was a mechanic, described how the pain medications he was prescribed by the doctor only brought temporary relieve. He also explained that he still felt severe chest pains every time he attempted to lift an object. In his words: The pain I had was in one part of my chest like this. When it happens, if I lift a light object like this it will pain me severely. It is up to four months now. The last time I went to the hospital for check-up, the drugs I was given then gave me some relieve from the pain. But when I lift something I will like feel the pain again. I feel it in like one part of my chest . . .
Other participants reported experiencing pains in their ribs. Some used the metaphor of a dart thrust through their ribs to capture the pain sensation ("it was as if someone used arrow to hit my side"; Obot, aged 22). Other participants, like Akpan (aged 24) quoted below, used the word "hook" to describe their pain experience: The pain that I had, there is how if I sit like this it will start to hook me in this side (the left ribs). I just bought drugs like that and took them. There is how I will feel like cold like that. It even started bringing out rashes in my body . . .
For others, especially women, pain was experienced in the waist. Chronic waist pain was described as a debilitating and incapacitating form of pain which had a significant negative impact on daily functioning. Mary (aged 27) narrated: My own I have pain in my head and also in my waist. The one in the waist is the worst. It is so much sometimes that I cannot even stand on my own like I am standing now. That is the one that pains me the most, like more than the head one.
Taken together, the accounts presented in this section suggests that chronic pain, which was also often severe, was experienced as a cause of suffering by the participants. Chronic pain had disruptive effects on everyday life of the participants. We explore this theme more below.

Impacts of chronic pain
Interviews also captured the different impacts of chronic pain on the participants' lives. An important area of their lives that was negatively impacted by chronic pain was work, including both paid employment and informal economic activities. For example, Akpan (aged 24), who previously sold roasted plantain, attributed his pain to constant exposure to heat. He explained that he had to quit the trade because of the pain: It didn't used to allow me to always go to work. I was told to shut down for a while and treat the pain, and start again when the pain reduces. They said it was the heat from the roasting of chicken that I used to do that caused the pain. So, I had to stop the business.
He went on to explain how discontinuing the business led to loss of income, undermined his capacity to utilize health services, and made him dependent on relatives. For others, especially those employed in the formal sector, chronic pain was seen as a cause of work absenteeism with the attendant risk of losing employment. Emma (aged 38), for example, described how he had to give excuses for being absent from work due to pain: When it knocks me down it can keep me for weeks. I will have to treat malaria and typhoid with all those things. I also take purge (enema) with all those things . . . Yes, sure it affects me and I am not able to go to work. I will take excuse and say that I have to go and treat myself.
Participants whose livelihoods depended on daily earnings faced a peculiar adverse effect of chronic pain. Their inability to undertake income generating activities on day-to-day basis due to chronic pain meant they could not generate income to meet daily needs (e.g., food, water). In this fashion, chronic pain contributed to exacerbating pre-existing structural inequalities. Imeh (aged 35) narrated: It used to feel like if I hold something it will fall from my hand. I couldn't do any work because of how the pain was doing me in my chest. I would stay at home and it affected me from getting money to be able to eat and take care of myself. It really affected me because like I am someone who works everyday to make money to survive. So, if I don't go out to work in a day I will not have money.
In other cases, chronic pain did not precipitate a total discontinuation of economic activities. Instead, it significantly compromised work performance by undermining physical strength. This was often the case with artisans and manual labourers who earn a living through hard physical labour. Ini-Obong (aged 41), quoted earlier as being unable to work due to pain, told us: Like the hard work that I am doing. I am a mechanic. I repair engine. When I feel the pain like that, I will not be able to lift the engine because I don't have crane that is used to lift engine. I lift it by myself along with my fellow workers. I will not be able to lift it with them because the pain is affecting me in the chest.
Apart from work and income generation, chronic pain also compromised personal functioning and impeded the performance of daily activities. Participants described how inability to carry out daily activities altered their sense of a "normal day" (Rose, aged 33). Others, like Edidiong (aged 39) quoted below, described how chronic pain made self-care a daily burden: My own is that I didn't used to go anywhere because whatever I am doing is affecting me. It didn't used to allow me to go anywhere until when I take drugs and use hot water to shower. I used to wear thick clothes and stay at home for some days before I was able to go out. (Edidiong, aged 39) Other participants described how pain affected their social relationships by making them a burden to friends and relations. Chronic pain exacerbated socio-economic marginality through its adverse effects on work and income generation, daily functioning, and social relationships.

Healthcare experiences
During interviews, we asked participants about their healthcare experiences, particularly their interactions with healthcare providers (e.g., doctors). Some participants reported pleasant and supportive interactions. For example, a participant recounted an affirming interaction he had with a doctor, who was a friend of his relative. This context of support and affirmation made it possible for the participant to disclose his drug use to the doctor. In his words: This is a case of accusation of malingering, which is a common experience among chronic pain patients (Upshur et al., 2010). The accusation is partly due to the lack of knowledge and skills to communicate the pain appropriately to the healthcare provider. The interaction fostered feeling of unworthiness for health services, which is seen in the phrase "in the wrong place". Others reported being derided and scorned by nurses due to drug use. Emma (aged 38) narrated: There was a day I went to the hospital. In my mind I was praying to meet male doctors. Unfortunately, I met women from the nurse that attended to me to the doctor that prescribed drugs to me . . . The doctor asked me questions. She asked me if I smoke cigarette, and I said no. She said what about hard drugs, and I told her I take drugs . . . The negative experience I had was with those nurses. They used it (drug use disclosure) to laugh.
Emma's concerns about meeting female providers were borne out by the experience he had. Culturally-defined gendered norms may shape how male patients experience discriminatory healthcare interactions. Other participants described perceived stigma that prevented them from disclosing their drug use. This suggests that perceived stigma could influence healthcare interactions. Peter (aged 27) stated: They asked about if I use drugs. I lied at that point. I told them that I don't take drugs, but that the work I am doing involves fire and heat. I lied about that drug use part. But I told them that it is from the heat that I have been exposed to in my work. I didn't want them to see me badly for taking drugs.
Peter did not have the interactional skills that Ini-Obong did, which enables safe disclosure and positive interactions with healthcare providers. Accounts also captured everyday stigmatization and discrimination perpetrated against PWUD, expressed through disparaging remarks and unwarranted questionings about drug use. These produced feelings of shame that made some participants to disengage from health services. For example, Mandela (aged 27) told us: The nurse asked me questions. I told her plainly that I use drugs -all kinds of drugs. The woman started being rough with me. She used strong words with me that really provoked me. I couldn't do anything so I was just looking at her. That is why since that day I left that hospital with that embarrassment, I have not gone back there again. I have also not gone to any other hospital.
It can be seen from the above quote that the verbal abuse Mandela endured was due to his forthrightness about his drug use. Mandela's frankness about using all kinds of drugs may have signalled a lack of self-discipline or a failure to engage in risk reducing practices, key cultural capital resources that make for positive healthcare interactions (Shim, 2010). The absence of these critical CHC resources may explain the negative experience he had with the nurse.

Barriers to health services
In addition to negative healthcare experiences, the participants faced social and structural barriers to health services. In this context, we draw on structural vulnerability to account for how the participants' marginal socio-economic status and drug consumption contributed to inadequate pain management by impeding their access to health services. A major barrier experienced by participants were lack of funds to bear the cost of health services. Lack of funds placed many of the participants in a situation where they could not utilize health services even though they recognized the need for such services. As Ini-Obong (aged 41) explained: The hospital is good because those people are on training. They train normally very well. When you go to the hospital, the way the people (health professionals) do things you will know that they are working with sense. The only problem I have is money. Money is very hard these days. Things have become very difficult. Even the work that we are doing, we are now in rainy season and jobs are not many the way they used to be. Things are very difficult. That is where the problem comes in.
This quote shows how poor socioeconomic conditions affecting the participants contributed to low access to health services. Lack of funds to cover medical expenditure made the idea of going to the hospital seem absurd. Going to the hospital without money was seen as exposing oneself to ridicule and humiliation at the hands of uncaring health workers. Emma (aged 38) told us: Everything is money. They say this one, it is money. They say that one, it is money. So, when you don't have the money and you go to the hospital you are a very stupid person because the way they will treat you will be as if your own is too much. Even the way they will talk to you.
Emma intimates that health services are available to those who have the means to procure them. Those who could not pay (like the participants in this study) exposed themselves to abuse and derision when they visited health facilities. Faced with socioeconomic barriers to services, participants often chose to self-manage pain instead of going to hospital. Edidiong (aged 39) explained how he choose to cope with pain rather than seek hospital treatment: My heart was telling me that this is not a hospital thing because it was not something that I was staying in the bed all the times. I could get up and sit, and even walk around. . . . I could walk about and take drugs till it subsided. That is why I thought it was not something to go to hospital.
Refusal to seek biomedical treatment for pain that they considered bearable meant that participants sought care when pain intensified or persisted. This practice, which contributes to inadequate pain management, shows how socio-economic barriers to healthcare creates vulnerability to negative health outcomes for PWUD. Denial of opioid medications due to restrictions on dispensing of opioid analgesics also posed as a barrier to pain management. Amanam (aged 31) explained: Hospital and pharmacy will not give you tramadol. It is a drug that is controlled, and government does not allow people to be taking it like that. So, because of that pharmacy will not give you tramadol anyhow like that.
Participants also described how healthcare providers were cautious about dispensing opioid analgesics to chronic pain patients with a history of drug use due to fear of misuse. Prescribing practices, rooted in drug use criminalization and stigma, operated as institutionalized barriers that impeded access to pain management. Ete-Obong (aged 32) stated: The woman (nurse) gave me drugs, but she didn't give me the one that should cure the pains (tramadol) because she said I will abuse it. She didn't give me those ones, she gave me those light ones . . . She said that I have been taking too much tramadol (non-medically). She didn't include that one.
An interesting finding in regards to institutional barriers to health services was how health insurance schemes discriminated against PWUD. A participant (Nkweini, aged 26), who was enrolled on health insurance as a formal sector worker, explained that insurance companies do not pay for health conditions that are linked to drug use. This made him to conceal his drug use to avoid being denied treatment: They (insurance companies) don't treat things that have to do with drugs. If you have problem related to drug abuse they will not treat it. That one does not concern them because it is not your work place that sent you to take drugs. If you have eye problem, malaria, even if you want to do surgery. You will pay half and insurance will pay half. But drugs thing, once they hear it they may drive you away.
The above quote highlights systemic discrimination in health insurance provisioning that go beyond limited coverage. The NHIS was adopted to facilitate universal health coverage. The participants' accounts show that this goal may be thwarted by discriminatory practices that foster exclusion of some enrolees.

Discussion
There is a growing academic literature on chronic pain experiences and biomedical pain management among PWUD. But most of the existing literature on this subject originate from research conducted in western industrialized societies. The findings presented in this study is from a research conducted in Nigeria. They contribute to redressing the paucity of research on experiences of chronic pain and healthcare interactions among PWUD in Africa. In this study, we used cultural health capital and structural vulnerability as theoretical approaches to understand the impact of cultural competencies (or the lack of such), and socioeconomic marginality and drug use stigma on pain management experiences of PWUD. We demonstrate how chronic pain management is shaped by conditions of poverty and social marginalization, and also explicate the structural and institutional dynamics that impede access to pain management for PWUD.
Corroborating previous studies (Glenton, 2003;Lillrank, 2003;Toye et al., 2013;Zajacova et al., 2021), the findings of this study show that chronic pain was intractable, caused untold suffering and had negative effects on the lives of the participants. Chronic pain adversely affected work and income generating activities. It disrupted daily routines and altered the sense of a normal day. It also compromised daily functioning and caused a strain in social relationships. Further, chronic pain had a significant negative effect on the livelihoods of poorer participants, especially those who subsisted on daily earnings. It undermined their ability to generate income to meet subsistence needs and made them dependent on relatives who were already over-burdened. The findings call attention to how lived experiences of chronic pain are shaped by conditions of poverty and marginalization affecting the lives of many Nigerians. The disproportionate effects of chronic pain on the poorer participants corroborate the need for a public health approach that emphasizes the importance of equity in addressing chronic pain (Goldberg & McGee, 2011).
Previous studies have documented stigma and discrimination experienced by PWUD in healthcare settings, and how these experiences contribute to inadequate pain management (Dassieu et al., 2020;Voon et al., 2018). Our study similarly captured negative healthcare interactions, including accusations of malingering that generated feelings of unworthiness for healthcare, stigma and discriminatory practices from healthcare providers due to participants' drug use, and gender dynamics wherein male participants felt derided by female providers. Findings also indicated that the outcomes of healthcare interactions were influenced by the existence or absence of cultural health capital, particularly interactional styles and verbal competencies (Shim, 2010). Thus, while some participants (such as Ini-Obong) experienced more satisfying interactions with healthcare providers partly because of honesty and willing disclosure of drug use, others (such as Mandela) had very negative interactions because their forthrightness about using drugs heavily and frequently may have been interpreted by their providers as a lack of self-discipline or a failure to manage risk (Shim, 2010).
The findings contribute to emerging literature that explores how patients cope with pain and other chronic illnesses in conditions of poverty and marginalization. Studies have shown how social deprivation exacerbates PWUD's vulnerability to chronic pain and how they rely on illegal drugs to manage pain amidst structural impediments to health services (Dassieu et al., 2020). Others demonstrate the importance of understanding how conditions of poverty and social marginalization shape pain management experiences of PWUD (Boucher et al., 2022;Webster et al., 2019). This study highlights structural and institutional barriers to pain management for PWUD, including cost of health services and lack of funds to cover this cost. Our study shows how cost impacts on chronic pain management among PWUD. The findings show how increased cost of health services, in a context of low government funding and significant private financing of healthcare (Odunyemi, 2021), impeded access to services and created a context of risk for negative health outcomes due to delay in the uptake of care. Barriers to health services were exacerbated by the structural vulnerability of PWUD, including socioeconomic marginality and drug use stigma.
Discriminatory prescribing practices linked to institutionalized restriction on dispensing of opioid analgesics also contributed to inadequate pain management. Studies have reported inadequate pain management among PWUD due to denial of prescription opioids and labeling as "drug addicts" in healthcare settings in North America (Busse et al., 2017;Dassieu et al., 2019). In Nigeria, a previous research has reported denial of prescription opioids to female patients due to suspicions of drug-seeking and appearance factors that suggested drug addiction (E. E. Nelson, 2022). The present study contributes to existing literature by showing undertreatment of pain among PWUD due to accusations of malingering and reluctance to prescribe opioid analgesics for fear of misuse. Discriminatory prescribing practices was part of a spectrum of institutional barriers to pain management for PWUD that included a prohibitive health insurance scheme that disenfranchised patients with substance use problems. We argue that everyday negative experiences of PWUD in healthcare settings (including stigmatizing interactions with providers and denial of prescription opioids) are expressions of deeper dynamics of exclusion mediated through institutional policies and clinical practices. Addressing these fundamental structural and systemic problems is germane to improving biomedical pain management for PWUD.

Limitations
This study is based on self-reports of pain, which is subject to social desirability bias. For example, it is possible that the participants may have exaggerated their pain or negative interactions with health workers to elicit sympathy. Future studies should use longitudinal and observational methods to better understand chronic pain experience and management. Further, the views of female participants were insufficient due to fact that we were only able to recruit a small number of female PWUD. However, a previous study with women reported similar findings (E. E. Nelson, 2022), which shows the validity of our findings.

Conclusion
This study explored healthcare experiences and barriers to chronic pain management for PWUD in a Nigerian city. The key contributions of the study to the existing literature on chronic pain experiences and management for PWUD are two-fold. First, it shows how specific CHC resources contributes to improved health-care interactions for some PWUD, while the lack of such resources fostered negative experiences for others. Secondly, the study demonstrates the utility of structural vulnerability for conceptualizing access to health services by showing how PWUD's marginal socioeconomic status amplified social and structural barriers to services and created a context of risk for inadequately managed pain. The findings indicate a need to combine structural interventions with biomedical services in order to improve utilization of pain management for PWUD. In addition to providing opioid medications for pain relief, adopting culturally safety approaches to service provision, combating stigma and discrimination against PWUD, and improving socioeconomic conditions could contribute to better pain management and general well-being for PWUD.