First dual-frame telephone survey for non-communicable disease risk and protective factors: Methods and main findings from a central Brazilian state, 2022.

Objectives: To Describe the methodology used in the first risk factor survey for non-communicable diseases in Goiás, a central state of Brazil and identify differences in prevalence of risk and protective factors for chronic disease between landline and mobile phone users. Study design: A cross-sectional study. Methods: A cross-sectional study was conducted using telephone interviews via landlines and mobile phones. The Random-Digit Dialing probabilistic sampling method was used to select phone lines. The Rake method weighted the data and the hot deck technique imputed missing weight and height data. A total of 5018 individuals residing in Goiás were stratified by sex, age group, education level and health macro-regions. Operational, demographic characteristics and prevalence of risk factors were evaluated, with crude and adjusted prevalence ratios calculated using the Poisson regression model. Results: Mobile telephony offered some operational advantages, while refusal rates were lower for landlines. Landline telephony underestimated men, adults and individuals with fewer years of schooling, while mobile's underestimated the elderly. Significant differences in prevalence were found for 16 indicators. Mobile phone users showed higher prevalence of risk factors, while landline's showed higher prevalence of protective factors. Conclusion: The use of both landline and mobile telephony was necessary to ensure population representativeness. However, new strategies are needed to improve participation in future surveys.