Mixed-methods protocol for the WiSSPr study: Women in Sex work, Stigma and psychosocial barriers to Pre-exposure prophylaxis in Zambia

Specific objectives

The Women in Sex work, Stigma and PrEP (WiSSPr) mixed-methods study aims to (1) measure the association between multiple stigmas on PrEP initiation and persistence among HIV-negative adult WESW and (2) qualitatively explore the enablers and barriers (interpersonal, psychosocial and structural) to initiating and persisting on PrEP. The qualitative aim will complement and contextualise 14–16 findings from the quantitative results. We hypothesize that WESW with high levels of any type of stigma will be less likely to initiate and persist on PrEP.

Conceptual framework

Interview guides will be informed by the Community, Opportunity, Motivation – Behaviour (COM-B) framework to assess how these components drive engagement with PrEP services.17 18 The COM-B model is commonly used in HIV prevention because it offers a framework to guide the development and implementation of targeted interventions, thereby enhancing the efficacy and reach of HIV prevention programmes.19 This framework will guide us to identify deficits in knowledge or skills (Capability), environmental and social contexts (Opportunity), and personal motivations and attitudes (Motivation). This integrated approach ensures that all relevant aspects of behaviour change are considered, leading to more effective and sustainable health outcomes.

Directed acyclic graph

Directed acyclic graphs (DAG) visually synthesise a priori knowledge about the hypothesised relationships between variables of interest, helping to identify causal pathways and potential confounders that could bias the results. We propose confounders based on their known association with stigmas and PrEP persistence, using evidence from published studies addressing similar questions. Controlling for the following variables will be sufficient to block any unconditionally open, non-causal backdoor paths that could lead to confounding: age, community hub, duration of sex work, and education (figure 1).

Figure 1

Directed acyclic graph illustrating the causal effect of stigma on PrEP persistence. PrEP, pre-exposure prophylaxis.

Study design

We will use a prospective observational cohort study design with mixed methods to characterise PrEP outcomes for HIV-negative WESW in Lusaka, Zambia. Trained research assistants will administer a one-time, 75-item psychosocial survey to participants and follow them prospectively in the electronic medical record. For the qualitative aim, we will conduct in-depth interviews (IDIs) with WESW to get perspectives of prevention services with peer navigators who are both recipients of care and supporters of health service delivery.

Mixed-methods integration

We will use the NIH ‘Best Practices for Mixed Methods’ guidelines to design, analyse and interpret qualitative and quantitative data in mixed-methods research.20 Specifically, we will employ a convergent parallel design that collects both qualitative and quantitative data concurrently and separately, prioritising both the quantitative and qualitative strands equally but keeping them independent during analysis. We will interpret the extent to which the two sets of results converge, diverge, relate to each other and/or combine to create a better understanding in response to the study’s overall purpose.20

Study setting

The study population is composed of adult WESW who are living or working within the catchment areas of two community hubs located within urban Lusaka. Based on CIDRZ’s prior published work, we anticipate that the study population will be comprised largely (63%) of younger women (18 – 29 years old). 10

Study exposures and outcomes

Table 1 identifies the primary outcomes of PrEP initiation and persistence from pharmacy dispensations records in the last 90 days for survey participants. Several studies have accessed this data from the national electronic medical record system SmartCare.21 22 CIDRZ is a key Smartcare implementing partner and routinely leveraging this data to optimise service delivery for KP in KPIF in order to better understand outcomes for HIV treatment and prevention in the national HIV programme.23–28 Table 2 identifies the independent variables of interest including sociodemographic history, intersectional stigma (everyday discrimination scale),29 substance use (ASSIST),30 depressive symptoms (Patient Health Questionnaire, PHQ), 31 as well as sex work, HIV and PrEP-related stigmas and resulting discrimination using established questionnaires.32–34 The qualitative outcomes are insights into the enablers and barriers to PrEP use informed by participants’ lived experiences according to the COM-B model.

Sample size

We determined the minimum sample size using Demidenko’s method for logistic regression with binary interactions, informed by effect size and variance data from Witte et al’s study on PrEP acceptability among women in Uganda.35–37 Sample size considerations are based on our primary outcome of PrEP initiation and informed by preliminary programmatic data that formed assumptions about baseline HIV prevalence and estimated PrEP initiations. Each site tests an average of 200 WESW per month, which will allow an estimated 800 women to be tested during the 2-month enrolment period. We project approximately 56% (448) will test HIV-negative, and of these, we estimate 403 (90%) will be eligible, and 350 (87%) will agree to initiate PrEP. Due to time and resource limitations, we seek to enroll a sample of 300 eligible WESW. Assuming 5% of participant medical records cannot be found, a total cohort of 285 PrEP users would allow us to estimate the prevalence ratio of stigma on PrEP initiation of 1.98 or higher (positive association), or 0.50 or lower (negative association) at 80% power with a significance level of 0.05. We aim to recruit 18 participants for IDIs, based on prior research with this population and qualitative methodology guidelines suggesting that 6 – 10 interviews per subgroup are sufficient to reach thematic saturation14 20

Participant recruitment

The study will start in July 2023. WiSSPr will recruit 300 participants from a convenience sample of WESW who are receiving HIV services from two community-based hubs which have been functioning as MoH drop-in wellness centres since October 2021. All HIV testing and prevention services at these community hubs are led by teams of KP and MoH staff. Outreach activities take place in venues where WESW socialise, such as brothels, bars, or the home of a KP. Recruitment activities will take place during these outreach activities. KPIF programming leverages KP social networks to mobilise WESW for recruitment into the study. A total of 18 participants, including 6 peer navigators, 6 WESW who discontinue PrEP after initiation, and 6 WESW who continue on PrEP, will be purposively sampled for IDIs, or until we achieve thematic saturation.38 Qualitative data collection will take place at least 30 days after the quantitative recruitment begins, in order to sample women who initiate a 30 day supply of PrEP but do not return to pick up another refill. Figure 2 outlines the WiSSPr study recruitment process.

Figure 2

The WiSSPr study flow diagram summarises the stages of participant recruitment and follow-up. PrEP, pre-exposure prophylaxis; WiSSPr, Women in Sex work, Stigma and PrEP.

Recruitment will end when 300 participants have been enrolled for the survey and 18 participants enrolled for interviews. PrEP event data will be abstracted from SmartCare approximately 3 months after the final participant’s enrollment. Study activities, including qualitative data collection, data quality control and assurance, and data analysis, are anticipated to continue until the planned end of the study in September 2024.

We will engage the community advisory board (CAB) in collaborative decision-making on: (1) how best to conduct outreach to venues that WESW frequent, (2) how to engage leaders in the sex work community to inform them about this study, and (3) to encourage WESW participation in a way that minimises social harms. Box 1 identifies the inclusion and exclusion criteria for the study. Written informed consent in English or local languages (ChiNyanja or IchiBemba) will be obtained before enrollment. As an added measure of protection for this marginalised population, participants must complete an informed consent quiz to ensure that they understand the potential risks of study participation. Participants will receive the Zambia Kwacha equivalent of US$5 per survey and interview as compensation for their time.

Quantitative data collection

A team of 3–5 trained research assistants will administer a tablet-based survey (online supplemental file 1) for quicker data entry, real-time quality control and logic checks to reduce data entry errors and immediate data backup compared with paper. Surveys, estimated to take 60 min each, will be conducted in English, ChiNyanja or IchiBemba, based on participant preference. The survey tool will be piloted with CAB members and peer navigators. Patient medical records are routinely entered by KPIF programme staff into a secure, standardised electronic data capture system, from which we will extract relevant deidentified data using the participants’ SmartCare ID numbers.

Qualitative data collection

We will use a semi-structured interview guide (online supplemental file 1) with open-ended questions and probes to explore specific themes related to HIV prevention and intersectional stigma. This guide allows some flexibility for participants to follow topics of interest to them. The themes we will explore are informed by the COM-B conceptual framework which include perceived and enacted stigma, the impact of intersectional stigmas on health service utilisation service needs, enablers such as psychosocial support or the trustworthiness of the healthcare system. The guide also includes modules on PrEP where the interviewer will explain oral and long-acting injectable PrEP and assess participants perceptions of the advantages and disadvantages and willingness to use these different PrEP options. Participants will be asked about their own perceptions as well as their perceived opinions of their peers, as this approach has yielded richer responses in previous studies.39 Interviews are estimated to take 60 minutes and will be conducted in English, ChiNyanja, or IchiBemba in a private location at a community safe space or other similarly secure location determined by participant preference. We will request permission to audio record interviews for transcription and translation. All interviews will be conducted by a single trained interviewer. The interview guides will be piloted with CAB members before implementation.

Data management

SmartCare serves as a repository of clinical data for WESW accessing KPIF services. A secure server will be used to store encrypted study data, including the study database. Quantitative data collected on tablets will be transmitted to the server at the end of each day. To ensure data safety, there will be daily backups, and data will also be stored on secure drives.

All IDIs will be audio recorded. Audio recordings will be transcribed verbatim and then translated into English in a single step by qualified research staff. The audio recordings will not be marked with any identifying information. Instead, interviewers will use unique participant codes to label the audio recordings. No personal identifiers will be used, and any identifiers inadvertently mentioned during interviews will be purged from the transcripts prior to analysis.

All medical records that contain participant identities are treated as confidential in accordance with the Zambian Data Protection Act. All study documents related to the participants will only include an assigned participant code. Only research staff will have access to linkable information, which will be kept strictly confidential. All records will be archived in a secure storage facility for 3 years after the completion of the study per local regulatory guidelines, after which time all electronic data will be deleted from project servers and hard drives, and all paper-based records will be disposed of.

Quantitative data analysis

We will conduct univariable analyses to examine whether there are differences in the levels of stigma, discrimination, depressive symptoms and substance use disorders among those who initiate PrEP versus those who do not, stratified by community hub. We will report the prevalences of HIV and PrEP stigmas, discrimination due to intersectional stigma identified by the Everyday Discrimination scale, depression and suicidal ideation identified by PHQ, and substance use disorders identified by ASSIST. We will sum all items within a screener to a total score before collapsing data into categorical variables. For cases where missing data are more limited (approximately < 5%), for single items and measures, we will use mean imputation to derive a score. If there is substantial missingness (> 10%) then we will use missing data methods such as multiple imputation.

A PHQ-9 score ≥ 10 is commonly used in primary care settings as a cut-off for probable major depression.40 PHQ-9 cut-off scores of 5, 10, 15 and 20 will be categorised as mild, moderate, moderately severe and severe depression, respectively. The ASSIST gives 10 risk scores for tobacco, alcohol, cannabis, cocaine, amphetamine-type stimulants, inhalants, sedatives, hallucinogens, opioids and other drugs. The score is higher the more frequently the participant reports using substances. For alcohol use, we will use cut-offs of 11 and 27 for moderate and high risk of substance use disorder. For all other substances cut-offs of 4, and 27 for moderate and high risk.30

PrEP initiation will be calculated using the total number of individuals initiated on PrEP over the total number of HIV-negative individuals who were enrolled and eligible for PrEP. We refer to the complement of discontinuation as PrEP persistence.41 We define immediate discontinuation for those who initiate a 30 day supply of PrEP and do not return for any refills over the 108 day observation period in alignment with national antiretroviral therapy (ART) programme guidelines on continuity of care and management of missed appointments.21 42 We will calculate a medication possession ratio (MPR) of total days with medication in patient possession to the observation period, as a measure of engagement in services and report both the MPR and IQR (table 1).

We will use Stata (V.16.1, StataCorp) for analysis, reporting descriptive statistics to characterise the study population and bivariate associations between key exposures and immediate discontinuation with Pearson’s χ² statistics. We will fit Poisson regression models, which will estimate prevalence ratios of discrimination, PrEP stigma and HIV stigma on immediate discontinuation of PrEP over a 3-month follow-up period, controlling for confounders identified by the DAG. Adjusted prevalence ratio estimates will be reported with 95% CIs and p-values at the alpha = 0.05 significance level.

Qualitative data analysis

We will analyse the qualitative data using established analytical software (NVivo, QSR International, Melbourne, Australia) through deductive reasoning based on our conceptual model and inductive reasoning to identify major and minor themes emerging from audio recordings and transcripts. The process of eliciting themes will involve familiarisation with interview transcripts and noting emergent themes, adapting our conceptual framework as necessary, performing open coding, developing a codebook, performing data reduction, data display using matrices and/or tables, and interpretation to map out relationships in the data. Two coders will review these data, independently identify emergent themes, and confer to agree on final coding and findings. We will apply established qualitative research principles in our analyses, including negative case analysis and respondent validation.43 44

Participant attitudes and preferences relating to elements of future stigma-reduction intervention, psychosocial support provision and long-acting injectable PrEP will be described qualitatively. We will strive for critical reflexivity by outlining our point of view in relation to the interviewees of the study during data collection and will state how positionality and context may have affected the findings. The credibility and trustworthiness of qualitative data will be assured through member-checking by participants themselves.45

Ethics and dissemination

WiSSPr was approved by the Institutional Review Boards of the University of Zambia (#3650 -2023) and University of North Carolina, the Zambia National Health Research Authority and the Lusaka Provincial and District Health Offices. A final study notification will be sent on completion of the study, or in the event of early termination. Participants are free to withdraw from the study at any time without affecting their right to medical care.

The study findings will be disseminated to KP community members, providers, researchers and policy-makers. The CAB will review preliminary results and advise on meaningful dissemination to the KP community, National AIDS Council, National HIV and Mental Health Technical Working Groups, investigators and stakeholders. The information will be presented at conferences or published in peer-reviewed journals. Participants’ personal information will not be included in any publications.

Patient and public involvement

We will use principles of community-based participatory research (CBPR) to ensure patient and public involvement in this study. CBPR is a research paradigm that focuses on relationships between academic and community partners, with principles of co-learning, mutual benefit and long-term commitment.46 CBPR incorporates community theories, participation, and practices into the research efforts and plays a role in expanding the reach of implementation science to influence practice and policies for eliminating health disparities.46 47

To collaboratively develop this study with clients and the public, we will use CBPR principles and create a CAB with Lusaka District Health Office and two KP-CSOs working in the study sites: Zambia Sex Workers Alliance and Tithandizeni Umoyo Network. As a study team, our first priority is to develop trust with people engaging in sex work. Trust development is a construct of CBPR and has also emerged as a synthesising theory.48 49 Trust types are ordered along a relative continuum from least (trust deficit) to most (critical reflective) trust which reflects an ability to discuss and move on after a misstep.48 Given the historical marginalisation and stigmatisation of WESW in Zambia, we anticipate a trust deficit and have allocated time and budget to nurture and develop trust along this continuum. We will build trust through ‘role-based trust’ as researchers, ‘proxy trust’ from the reputation of CIDRZ and KP CSO team members’ work with KPs in Zambia, and ultimately aim to establish ‘critical reflective’ trust.

The research questions and outcome measures were developed in collaboration with the CAB, ensuring they reflect the priorities, experiences and preferences of the sex worker community. Input from the CAB helped tailor the study to address the most pressing issues identified by the community. The study team will work with the CAB to adapt the study within complex systems of organisational and cultural context and knowledge. Collaborative decision-making will occur prior to the study launch, throughout the recruitment period, and during dissemination. The CAB will provide feedback on the potential burden of the intervention and the time required for participation, so that the study minimises inconvenience and respected participants’ time constraints. All partners will decide what it means to have a ‘collaborative, equitable partnership’ and how to make that happen. 50 The CAB will advise on which community hub to recruit from first, and how to work with community leaders to adapt study standard operating procedures to not disrupt service implementation at study sites. They will also advise on how to minimise potential risks to participants, including ways to reduce emotional distress and ensure physical safety. Participants experiencing emotional distress will be referred for psychosocial support with evidence-based mental health therapy specialised for those with depression and substance abuse, with the KPIF providing transportation and a peer navigator accompanying them to the facility providing these services. The CAB will be actively involved in planning the dissemination of study results to participants and the wider community, helping decide what information to share, the timing of the dissemination and the most appropriate formats for communicating the findings.