Background/purpose: Dengue fever is an important public health problem in Southern Taiwan. The purpose of this study was to develop a dengue scoring system using a three-stage process, which may be used as a guidance tool for the early diagnosis of dengue fever.
Methods: A retrospective study was conducted to identify factors useful for the early diagnosis of dengue fever. We assessed the clinical and laboratory features of 89 adult patients with dengue from 2002 to 2004 at a community-based hospital. They were compared with 14 patients with scrub typhus, 104 with Q fever, and 35 with murine typhus, which might present similar symptoms and signs as dengue infection. A scoring system was designed after analysis of the retrospective study and with the assistance of 10 expert clinicians. For the second stage, we evaluated efficiency in differentiating dengue fever from Q fever, scrub typhus and murine typhus in three hospitals from 2002 to 2005. For the third stage, we prospectively used the dengue scoring system for 498 cases that clinically were suspected as having dengue infection in the city of Kaohsiung from January 2006 to September 2006.
Results: The performance of the scoring system was 88.1% sensitivity, 94.9% specificity, 95.7% positive predictive value (PPV), and 86.1% negative predictive value (NPV). Evaluation of the scoring system at the third stage revealed 90.7% sensitivity, 86.9% specificity, 81.4% PPV, and 93.6% NPV.
Conclusion: The dengue scoring system had a high NPV that might be helpful in the early diagnosis of dengue fever in adults before laboratory data are available.