Analysis of dengue cases according to clinical severity, São Luís, Maranhão, Brazil.

Severe dengue cases have increased in Brazil since 2001, with the first records in Maranhão dating back to 2002. The aim of this study was to determine the prevalence of severe dengue cases by age group and the possible risk factors. This was a study of secondary data on dengue in residents of São Luís, Maranhão, Brazil, using probable cases notified to the National Mandatory Reporting System (SINAN) from 2002 to 2011. The diagnosis and classification of dengue were based on the Brazilian Ministry of Health criteria: dengue fever (DF), dengue hemorrhagic fever (DHF) and dengue fever with complications (DWC). DHF and DWC were considered severe dengue, and DF was classified as non-severe dengue. A logistic regression analysis was performed with severe dengue as the outcome. During the study period, 1,229 cases of severe dengue were reported; of these, 812 in patients under the age of 15 (66%). Among the risk factors evaluated, age under 15 years old (OR = 3.10, 95% CI = 2.69-3.57, p-value = 0.001) was associated with severe dengue. The prevalence of severe dengue in children under the age of 15 was higher, and only this age group was associated with the occurrence of severe dengue.