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 increased incidence of congenital syphilis (CS) can be attributed to the lack of penicillin. This study aimed to analyze the relationship between the benzathine penicillin 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 who were living in the city of Rio de Janeiro. The benzathine penicillin supply measure for use in gestational syphilis considered the ratio between (1) the number of bottles dispensed to health facilities in each neighborhood and (2) 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 per 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 had an impact on the increase in the incidence of CS in Rio de Janeiro.