Setting
The Dominican Republic is one of the largest sex tourism destinations in the Caribbean with an estimated 100,000 women involved in the sex industry [22]. Sex work is not explicitly illegal in the country for people over the age of 18. Historically, the majority of sex work was establishment-based, but recent estimates suggest that more than 60% of FSWs independently solicit clients from streets, parks, beaches or other public places. FSWs who are establishment-based tend to work in brothels, bars, discos, liquor stores, or car washes. Even though sex work is not illegal in the country, harassment by police and other law enforcement officials is common [23, 24].
Study description
The pilot study employed a micro-longitudinal observational study design and was nested within an ongoing 5 year (2016–2021) NIH-funded parent study (5R01MH110158) in Santo Domingo [25]. Further details on the parent study are described elsewhere (see [25]). Women were eligible to participate in the pilot study if they met all the parent study’s inclusion criteria which included being at least 18 years of age, having a confirmed HIV positive diagnosis determined by a single rapid test, and having exchanged sex for money in the month prior to study enrollment. Additional inclusion criteria required for the pilot study included that women had used drugs in the 6 months prior to data collection [required for half the sample], were willing and able to complete a paper-based travel diary for 7 days, and were willing and able to answer electronic daily behavior diary questions for 7 days.
Participants were recruited from the parent study using selective/purposive sampling based on drug use. To determine drug use status, results from the parent study baseline survey were analyzed to determine participants who ever used/used drugs in the 6 months prior to data collection. Among the 200 women in the parent study at baseline, 36.5% had ever used drugs and 16% were current drug users. Thus, for the current study, drug using participants were randomly sampled from the 16% of current drug users in the parent study. The goal was to enroll a minimum of 25 drug using participants.
Non-drug using participants were randomly selected based on viral load detectability as defined by the parent study. Non-drug users were categorized as viral load detectable and non-detectable, and every 5th participant from each group was selected as a potential participant. The goal was to enroll a minimum of 25 non-drug using participants, half with detectable viral loads and half non-detectable. Adhering to the parent study’s recruitment processes, participant contact information was obtained from the IDCP coordinator and FSW peer navigators were used to contact and recruit participants.
Data collection activities included: (1) baseline questionnaire; (2) participatory geographic mapping; (3) daily activity space travel diary collected for 7 days and; (4) daily behavior diary collected for 7 days. Data collection instruments and measures were piloted, translated to Spanish, and adapted to the Dominican context. Written informed consent was obtained from all participants. Study enrollment was held at the Instituto Dermatológico Dominicano y Cirugía de Piel (IDCP) in Santo Domingo where the parent study was located. Ethics approval from the Internal Review Boards (IRB) at Tulane University and IDCP was obtained. The final analytic sample size was N = 51. A diagram of the data collection process is displayed in Fig. 1.
Participants received $10 USD for participating in the study and an additional $3 per day for completion of the activity space travel diary and the daily behavior diary (1 travel diary a day, 1 behavior diary a day × 7 days = $21). Compensation was provided at time of submission of the activity space travel diary following the 7-day data collection period. Transportation to and from the study site was covered for 2 trips. At the time of enrollment, cellphones were loaded with a pre-paid 7-day data package to cover Internet costs for the daily behavior diary.
Participatory geographic mapping of perceived risk environments
Given the limited availability of neighborhood-level data in the Dominican Republic, we used participatory geographic mapping to obtain data on perceived neighborhood risk characteristics and locations in Santo Domingo [26]. During baseline data collection, participants were asked to identify locations or areas they perceived as unsafe. More specifically, using Google Maps, we asked participants to locate areas and locations for sex work, crime and violence, police presence, drug use and trafficking, and poverty. While sex work itself is not inherently risky it becomes risky due to violence, stigma, lack of legal protection, forced substance use, and seclusion, which is why locations of sex work were characterized as potential risk environments [27]. Similarly, while poverty may not cause violence, areas with higher poverty rates are disproportionately affected by crime and violence which is why areas with higher levels of poverty were included as possible perceived risk environments [28]. Participants were then asked to rate the perceived riskiness or level of unsafety of the location as ‘high’, ‘medium’ or ‘low’. For each location participants were asked to provide the address or nearest cross section and a temporary point was placed at the location. Google Street View was used to verify locations and geographic coordinates (latitude and longitude) were obtained. For locations that were polygon or area-based, spatial boundaries were identified using cross-streets and landmarks. Using the satellite imagery as a guide, boundaries were demarcated and digitized. The name of each perceived risk environment, risk characteristic (e.g., sex work, crime and violence, police presence, drug use and trafficking, and poverty), risk rating (e.g., high, medium, low), and geographic coordinates were recorded in an Excel file. This exercise took an average of 30 min per participant.
Aggregated information per perceived risk environment location were calculated, including the number of times the location was mentioned by participants, the number of descriptive risk characteristics assigned to the location, and an average risk rating. The average risk rating was calculated by assigning a value to the risk category (where high risk = 3, medium risk = 2, and low risk = 1), and summing the total risk score across participants divided by the number of times mentioned. A weighted risk rating was also calculated taking into consideration the number of risk characteristics assigned to the location/area. The data were de-duplicated and imported into ArcGIS 10.6 (ESRI, Redlands, CA) where they were joined and overlaid on a base map of Dominican census tracts (barrio parajes) and road data.
Daily activity space travel diary
The best practice for activity space mapping is to use GPS technology because it minimizes recall and respondent bias and requires minimal investment by the participant; location, time, and speed are recorded in real-time at pre-determined time intervals (e.g., every minute). However, considering our study population and the context of sex work, the local research team was hesitant to use GPS for issues related to privacy and vulnerability. In the Dominican Republic, sex work is not explicitly illegal for people over the age of 18, but sex workers are frequently subjected to harassment by police and other law enforcement officials, violence by clients and partners, and societal stigma, so data are very sensitive. As an alternative to the more invasive form of GPS tracking, we captured participant activity paths for 7 days using a paper-based travel diary adapted from a study by Kwan et al. [5]. This format provided participants the flexibility to complete the diaries when they were in a secure location without the risk of others bothering them or finding out sensitive information.
During study enrollment participants received 7 travel diary forms, one for each day of the week. Participants were asked to record the location, address, time, presence of drugs and alcohol in the environment, main activity, transport method, and whom they were with for each place visited during the day from the time they woke up until they went to bed. As depicted in Fig. 2, the diary was designed as a grid with columns and rows. Visual icons accompanied by simple instructions were used to indicate the information to be recorded. Participants were showed how to complete the diary and provided the PI’s contact information in case they had questions.
To verify daily completion of travel diaries, participants were asked to send the PI a daily snapshot photo of the completed travel diary labeled with the participant’s unique ID via WhatsApp. Participants received a daily reminder via WhatsApp to complete the diary and to send a photo of the completed travel diary by the following morning by 12:00 PM, which was selected as the submission time due to the nature of the participants work and late hours. The information from the daily travel diaries was input to an electronic version of the travel diary. At the end of the 7-day data collection period, participants returned the paper travel diaries and were asked to clarify any entries that lacked information that was necessary for recording the latitude and longitude of each location. With the help of the participants, each location visited during the week was plotted on a Google Map file and the latitude and longitude recorded in an electronic version of the travel diary for that participant.
Each participant’s weekly travel diary information, which included latitude and longitude coordinates for each location visited during the week, was imported into ArcGIS 10.6 (ESRI, Redlands, CA). Activity paths were generated using the shortest roadway network tool, connecting point locations in order by day and time using the shortest distance along the roadway network. To calculate activity space risk exposure measures, activity paths were overlaid on the base map of Santo Domingo joined with the risk environment data and additional secondary spatial point data of risk outlets from the 2014 PLACE study [29]. The 2014 PLACE study was conducted in 6 regions of the country known to have high HIV prevalence. One objective of the study was to characterize and map risk locations frequented by key populations (e.g., sex workers, MSM, IDUs etc.) such as car washes, liquor stores, bars, hotels, construction areas, nightclubs, brothels etc. Locations were identified and captured via interviews with community informants about where key populations socialize and meet sexual partners.