Using Ethno-Epidemiology in a Prospective Observational Study to Increase the Rigour of Nested Qualitative Research

Ethnographic-epidemiological (“ethno-epi”) research methodologies are increasingly being used to examine health-related issues, including the experiences of people who use drugs. However, the complementary application of random sampling from a well characterised cohort and qualitative data collection methods in a single study has not been described. We address this gap by sharing insights from the implementation of a novel random stratified sampling technique to recruit participants from two large prospective observational studies of people who use drugs into a qualitative study about impacts of the COVID-19 pandemic on their lived experience. We aim to describe how an ethno-epi approach we used can enhance the validity, reliability and generalizability of research findings in mixed methods investigations. We do so by providing a step-by-step description of the process we used to determine participant eligibility and recruitment into the qualitative study. Although the approach is not without limitations, findings underscore how ethno-epi random sampling approaches can increase the credibility and trustworthiness of qualitative findings without compromising data depth and integrity. Our study makes an important contribution to the growing number of new creative approaches being developed in the mixed methods research field and we hope that by sharing our account it will encourage and support others to consider the use of ethno-epi approaches in health-related research.