Still on the Brazilian Response to the Microcephaly Epidemic: A Meta-analysis of 1,548 Pregnant Women from 13 Cohorts to Evaluate the Risk of Adverse Outcomes - Revista Brasileira de Ginecologia e Obstetrícia
Revista Brasileira de Ginecologia e Obstetrícia. 2023;45(4):169-170
In 2015, the scientific community was surprised by an epidemic of microcephaly initially identified in some states in northeastern Brazil. The first observations of an unusual increase in the number of cases of microcephaly were made by physicians in their clinical practice. After confirming the occurrence of this new phenomenon, came the challenges in determining its etiology, characterizing the spectrum of clinical manifestations and estimating the risk of its occurrence. These stages were successively fulfilled through ecological studies, case reports and series, and epidemiological studies. Clinicians were the first to raise the hypothesis that Zika virus infection during pregnancy was responsible for the adverse effects observed in children. Subsequently, the virus was detected and sequenced in the amniotic fluid of two pregnant women whose fetuses had microcephaly and specific IgM for Zika was detected in the cerebrospinal fluid of children with microcephaly. A case-control study showed the association between the Zika virus and microcephaly and at the same time, ruled out the role of other factors that could be responsible for its occurrence. The follow-up of cohorts of pregnant women allowed estimating the risk for microcephaly, abnormalities of the Central Nervous System (CNS) diagnosed by imaging, ophthalmologic and audiologic alterations and other birth defects in children born to Zika virus-infected mothers during pregnancy.– Although cohort studies have shown similar risks of microcephaly, estimates of the risk of other manifestations were diverse, indicating the need to use other analysis strategies with more robust estimates, such as meta-analysis.
In Brazil, cohort studies were developed by different groups of researchers. However, since the beginning of the microcephaly epidemic, Brazilian scientists were concerned about standardizing research protocols and collection instruments as far as possible to enable a joint data analysis in a later step. Several meetings were held to this end, initially involving Brazilian researchers and later researchers from different countries, with support of the Pan American Health Organization and the World Health Organization. In Brazil, the Zika Brazilian Cohorts (ZBC) Consortium was formed. By performing a joint analysis of data from Brazilian studies, it overcomes the limitations of isolated studies, notably the small sample size and consequent inaccuracy of estimates and lower representativeness. Among the contributions of the ZBC Consortium is the recently published article: “Risk of adverse outcomes in offspring with RT-PCR confirmed prenatal Zika virus exposure: an individual participant data meta-analysis of 13 cohorts in the Zika Brazilian Cohorts Consortium.” Next, we will highlight some of its points.
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In 2015, the scientific community was surprised by an epidemic of microcephaly initially identified in some states in northeastern Brazil. The first observations of an unusual increase in the number of cases of microcephaly were made by physicians in their clinical practice. After confirming the occurrence of this new phenomenon, came the challenges in determining its etiology, characterizing the spectrum of clinical manifestations and estimating the risk of its occurrence. These stages were successively fulfilled through ecological studies, case reports and series, and epidemiological studies. Clinicians were the first to raise the hypothesis that Zika virus infection during pregnancy was responsible for the adverse effects observed in children. Subsequently, the virus was detected and sequenced in the amniotic fluid of two pregnant women whose fetuses had microcephaly and specific IgM for Zika was detected in the cerebrospinal fluid of children with microcephaly. A case-control study showed the association between the Zika virus and microcephaly and at the same time, ruled out the role of other factors that could be responsible for its occurrence. The follow-up of cohorts of pregnant women allowed estimating the risk for microcephaly, abnormalities of the Central Nervous System (CNS) diagnosed by imaging, ophthalmologic and audiologic alterations and other birth defects in children born to Zika virus-infected mothers during pregnancy.- Although cohort studies have shown similar risks of microcephaly, estimates of the risk of other manifestations were diverse, indicating the need to use other analysis strategies with more robust estimates, such as meta-analysis.
In Brazil, cohort studies were developed by different groups of researchers. However, since the beginning of the microcephaly epidemic, Brazilian scientists were concerned about standardizing research protocols and collection instruments as far as possible to enable a joint data analysis in a later step. Several meetings were held to this end, initially involving Brazilian researchers and later researchers from different countries, with support of the Pan American Health Organization and the World Health Organization. In Brazil, the Zika Brazilian Cohorts (ZBC) Consortium was formed. By performing a joint analysis of data from Brazilian studies, it overcomes the limitations of isolated studies, notably the small sample size and consequent inaccuracy of estimates and lower representativeness. Among the contributions of the ZBC Consortium is the recently published article: “Risk of adverse outcomes in offspring with RT-PCR confirmed prenatal Zika virus exposure: an individual participant data meta-analysis of 13 cohorts in the Zika Brazilian Cohorts Consortium.” Next, we will highlight some of its points.
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