External validation of the estimate of prevalence of smokers in small areas by Vigitel, in Belo Horizonte, Minas Gerais, Brazil.

Objective: The study aimed to validate the estimates of adult smokers determined by Vigitel for small areas, defined by the Health Vulnerability Index (IVS).

Methods: The database of the Health Survey of the Metropolitan Region of Belo Horizonte (RMBH) carried out in 2010 and the data from Vigitel in the period from 2010 to 2013 were used to obtain estimates of adult smokers by IVS. With Vigitel, the estimate of smokers by IVS was obtained by the indirect estimation method in small areas. The prevalence of adult smokers was compared, considering RMBH as the gold standard. The t test was used to evaluate the difference between the means and the Pearson correlation, with a significance level of 5%.

Results: When stratifying by IVS in the household survey, the prevalence of adult smokers ranged from 13.39% (95%CI 11.88 - 14.91) for residents in a low-risk area to 22.9% (95%CI 12.33 - 33.48) among residents in a very high-risk area. With Vigitel, according to IVS, the prevalence of adult smokers ranged from 11.98% (95%CI 10.75 - 13.21) for residents in the low-risk area to 22.31% (95%CI 18.25 - 26.1) in very high-risk areas. The prevalence was similar between the two surveys, showing good Pearson correlation (r = 0.93).

Conclusion: The study points out that the estimates of smokers were similar in both surveys, showing the external validity of Vigitel. There was a gradient in prevalence, with progressive increase, identifying a higher proportion of smokers in high-risk areas.