Implementation of starfish sampling for invisibilised populations: a methods protocol of the BRAVE multi-site...

Immigrant populations, particularly undocumented immigrants, are often considered 'hidden' or 'hard to reach' in research. This invisibilisation-under-representation or exclusion in data collection-leads to data inequities and biased findings that fail to capture their unique experiences. Starfish sampling mitigates selection bias and improves access to invisibilised populations by recruiting 'seed' participants at randomly selected times and locations and leveraging their social networks to recruit the next wave of participants. In this protocol paper, we outline the sampling strategy for the BRAVE (Building community, Raising All immigrant Voices for health Equity) study, a multi-site, cross-sectional survey examining the relationship between immigration history and sexual and reproductive health (SRH) service utilisation among Asian immigrant women in the USA. This protocol is an adaptation of novel starfish sampling in combination with various data tools and a community-based participatory research approach.

Using data from the American Community Survey and insights from community partners, we will conduct community mapping across four study sites (Atlanta, Houston, Los Angeles County and New York City). We will select census tracts that reflect the primary ethnic groups of interest and diverse socioeconomic backgrounds. From these selected census tracts, we will construct a venue universe by identifying key activity areas for Asian immigrant women through data scraping from online sources. We will then randomly select venue-date-time combinations and deliberately choose various community engagement events for recruitment. Culturally competent field officers who are fluent in Asian languages will recruit participants at these events. Participants can refer up to three peers from their social networks to take part in the survey. Results will be presented as descriptive statistics and logistic regression models to test the association between immigration history and SRH service utilisation.

The overarching BRAVE study protocol was approved by the University of California Los Angeles Institutional Review Board (IRB) (IRB-22-0493-AM-016). The results will be disseminated through academic journal publications and relevant data will be shared with our community partners.