The shortage of benzathine penicillin and its impact on congenital syphilis incidence: an ecologic study in the city of Rio de Janeiro.

BACKGROUND The Pan American Health Organization indicates that the increased congenital syphilis (CS) incidence can be attributed to the lack of penicillin. This study aimed to analyze the relationship between the benzathine penicillin (BP) shortage and the significant increase in the incidence of congenital syphilis in the city of Rio de Janeiro from 2013 to 2017. METHODS We used a mixed ecologic study design (temporal and multiple groups). Analysis units were the neighborhoods (spatial) and quarters (temporal) during those years. The study population consisted of CS patients that were living in the city of Rio de Janeiro. The BP supply measure for use in Gestational Syphilis considered the ratio between: (a) the number of bottles dispensed to health facilities in each neighborhood and (b) the number of bottles necessary to treat pregnant women diagnosed with syphilis and their respective partners residing in each neighborhood. To evaluate the association between shortages and a significant increase in CS incidence, the negative-inflated zero-binomial regression model (longitudinal model) was used. RESULTS During the study period, the incidence rate of CS in Rio de Janeiro neighborhoods was on average 19.6/1000 live births. In the simple analysis, shortage was associated with a 2.17-fold increase in the risk of a significant increase in CS incidence. After adjustment for the sufficient minimum set, the strength of association increased to 2.23 (95% confidence interval, 1.15-4.30). CONCLUSIONS We conclude that the benzathine penicillin shortage impacted the increase in the incidence of congenital syphilis in Rio de Janeiro.