Application of the Respondent-Driven Sampling method in an online survey in Brazil: COVID-19 morbidity in the post-pandemic period

OBJECTIVE: To describe the methodological procedures used to collect and analyze data from an online survey carried out from July to December 2023 and to verify whether the obtained sample is representative of the Brazilian population. METHODS: A cross-sectional epidemiological study was carried out through social media, using the Respondent-Driven Sampling methodology to collect information from the Brazilian adult population. For sample weighting, a post-stratification procedure was used based on sociodemographic data of the 2022 Continuous National Household Sample Survey (PNADC-2022). Prevalence estimates of chronic noncommunicable diseases, self-rated health, and health behaviors estimated in the ConVid-2 survey were compared with the estimates from the 2019 National Health Survey (PNS-2019). RESULTS: A total of 3,805 individuals participated in the ConVid-2 survey. When comparing sociodemographic variables from ConVid-2 with those from the PNADC, we verified very similar proportions in both surveys. Regarding chronic noncommunicable diseases, we found discrepancies only in prevalence of asthma and depression in comparison with PNS-2019. As for lifestyle habits, the percentages of current smoking, adequate leisure-time physical activity, and consumption of healthy and unhealthy foods were similar in both surveys. The greatest difference was observed in screen use after the COVID-19 pandemic. CONCLUSION: The use of the Respondent-Driven Sampling method with the inclusion of recruiter-recruitee pairs enabled us to obtain more reliable estimates. Concerning lifestyle changes and the findings of this study, we highlight the need for actions aimed at promoting healthy behaviors and achieving greater advances in the control of chronic noncommunicable diseases.