Study indicates that dengue increases risk of maternal death

Dengue puts a quarter of the world's population under health risks, according to the World Health Organization (WHO). A study indicates that healthcare for pregnant women infected with dengue should be even greater, because the risk of death is three times higher than in pregnant women without the disease. The risk of maternal death is 450 times higher when the woman has dengue hemorrhagic fever, the most serious form of infection.

The main author of the paper is epidemiologist Enny Paixão, a researcher at the Center for Data Integration and Knowledge for Health (Cidacs/Fiocruz Bahia), and it was published as “Dengue in pregnancy and maternal mortality: a cohort analysis using routine data” in the journal Scientific Reports - Nature.

The study is part of the PhD thesis of Paixão, held at the London School of Hygiene and Tropical Medicine, under the guidance of Professor Laura Rodrigues. Last year, the research conducted by Paixão had already linked dengue during pregnancy with increased risk of fetal death. In addition to Cidacs/Fiocruz Bahia and the London School, the research was carried out with the participation of researchers from the Institute of Collective Health (ISC) at the Federal University of Bahia (Ufba).

Methodology

To obtain this evidence, the research used data obtained from government databases, so-called administrative data, from the Live Birth Information System (Sinasc), from the Information System for Notifiable Diseases (Sinan) and from the Mortality Information System (SIM). The study was performed using a technique called probabilistic linkage, in which information (such as name and date of birth) from different databases is crossed in order to find the same individual.

In the period between January 1, 2007 and December 31, 2012 there were 10,259 records of maternal deaths for different causes. In order to compose the studied sample, were excluded of the records: women diagnosed with abortion or with fetal deaths (since the comparison group were live births), the deaths of women who were not associated with either fetal deaths or live births, and those deaths with no data to associate or not with the dengue situation. Thus, in the end, 4,053 maternal deaths and 17,391,826 live births were used as the comparison group.

Relevance

The results found in the study show the importance of prioritizing diagnostic tests for dengue during the gestation period. When dengue was diagnosed by symptom analysis, this group revealed three-fold increased risk of death. But when the diagnosis was confirmed by laboratory tests, this risk increased by eight times.

When the patient presented the signs and symptoms of dengue hemorrhagic fever confirmed by laboratory analysis, there was an increase in maternal mortality by 450 times. The authors emphasize that physiological changes in pregnancy can mask symptoms of dengue hemorrhagic fever, making diagnosis difficult. This implies that, probably, there are cases of people with dengue hemorrhagic fever that have died without being diagnosed.

The study also noted that pre-eclampsia and eclampsia, complications associated with uncontrolled blood pressure in pregnancy, were more frequent in the dengue group. "In our study we found that the frequency of these complications was greater in the dengue group than in the comparison group, but other studies need to be done to verify this relationship," researcher Enny Paixão said. "When the infection is diagnosed, the patient should be followed closely to avoid death," she says.

Maternal deaths

For the study, the definition of the 10th revision of the International Classification of Diseases (ICD-10) by WHO was used, where maternal death is “the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes".