Time trend of Vigitel Brasil operation indicators (2006 to 2023).

Objective: To analyze the time trend of indicators from the Vigitel data collection operation between 2006 and 2023.

Methods: A methodological study that analyzed the temporal trend of three Vigitel operation indicators: eligibility rate, response rate and refusal rate, as well as the number of contacts answered according to days of the week and times of day. A series of linear regressions was used to identify temporal variations for the entire period (2006 to 2023) and for the final five years of this period (2018 to 2023).

Results: During the 17 editions analyzed, there was a decrease in the eligibility rate (-3.26 pp/year; p < 0.001) with the greatest magnitude in the most recent period (-12.23 pp/year; p = 0.010). Although the inclusion of mobile phones in the register in 2023 has mitigated the drop in eligibility, especially in recent years, the reduction has remained high (-10.43 pp/year; p = 0.020). The response rate also fell over the entire period (-0.78; p < 0.001) and, together with the fall in eligibility, represents an obstacle to the sustainability of the survey. On the other hand, the refusal rate also fell (-0.23 pp/year; p = 0.030), indicating the consistent quality of the system's operation. The number of contacts answered was concentrated on weekdays and between 9am and 8pm.

Conclusions: An analysis of the data from the Vigitel survey suggests that the methodology used has become fatigued, with reductions in eligibility and response rates over the years. Only the refusal rate, despite being far from its lowest levels, remains at satisfactory levels. The search for alternatives that make participation more convenient for the respondent is an important path for surveys of this nature, with a view to maintaining the quality of health surveillance in the country.