Adjustment of definition of suspicious case of dengue based on the association of symptoms and signs according to the medical registries, Costa Rica, 1998

In October 1993, a case definition for dengue based on the presence of fever and two or more of the following symptoms: headache, mialgia, arthralgia, retroocular pain and exantema, was established in Costa Rica. When applied in the National Surveillance Program, this definition had showed a general sensitivity of 36%. In the present investigation, the probability for the health personnel to diagnose a case of dengue based on the presence of a combination of symptoms and signs, was evaluated. The study was intended to suggest a dengue case definition to improve the sensitivity of the surveillance system. The study population fully correspond to the clinical files included in a previous report ("Evaluación del Sistema de Vigilancia Epidemiológico del Dengue utilizando como indicador la aplicación de la definición de caso sospechoso, Costa Rica, 1998"). This research corresponds to an analytical observational study. The association of difterent symptoms and signs to the possibiíity of diagnosing a dengue virus infection was evaluated by using a logistic regression analysis. Data evaluated included the clinical criteria described by health personnel in the patient's clinical files and the results of the laboratory tests indicated for the confirmation of dengue infection. The results showed that the best structured model for the suspicious case definition included fever (OR=1,7 IC95% 0,7-3,9), myalgia (OR=1,7 IC95% 1-2,9), arthralgia (OR=1,6 IC95% 0,8-2,9), exanthema (OR=2,8 IC95% 1,3-5,9), retroocular pain (OR=2,8 1C95% 1,5-5,3) and bleeding manifestations (OR=6,4 IC95% 1,3-30). The combination of these symptoms and signs allow the discrimination of dengue cases in the first step of the differential diagnosis. However, the application of this combination gives the system a sensitivity of only 25 %...