The natural history of dengue illness based on a study of hospitalised patients in Singapore.

Aim of Study: To study the clinical features of dengue illness in hospitalised patients in Singapore. Methods: One-hundred and thirty hospitalised patients with serologically confirmed dengue illness, from I April 1992 to 31 October 1992, were analysed retrospectively. Results: Teenagers and young adults between 15 to 30 years of age were most commonly affected. The male to female ratio was 1.3:1. The mean duration of fever and rash prior to admission were 5.2 ± 1.5 (mean ± SD) days and 1.7 ± 1.7 days respectively. Petechiae were present in 52.3% of the patients. Three-quarters of the patients with petechiae had platelet counts (PCs) of 100 x 10 3 ul -1 or less. Thrombocytopenia (PCs of 100 x 10 3 ul -1 or less) was first documented 5.8 ± 1.4 days after the onset of illness. The nadir of thrombocytopenia occurred on the 6.4 ± 1.6 day of illness. The mean duration of thrombocytopenia was 3.6 ± 1.6 days. Nineteen patients (14.6%) had non life-threatening clinical bleeding or coagulopathy, namely bleeding gums (9 patients), epistaxis (5), vaginal spotting/ menorrhagia (4) and prolonged PTT (3). Six patients (4.6%) required platelet transfusion because of severe thrombocytopenia (PCs less than 30 x 10 3 ul -1 ) and clinical bleeding. There was no secondary fall in the PCs over 2 or more consecutive days when the PCs were in the recovery phase. It took I more day to reach PCs of 100 x 10 3 ul -1 , the safe level commonly used in Singapore to decide discharge of patients, as compared to 80 x 10 3 ul -1 . At PCs of 80 x 10 3 ul -1 or more, 2 patients had bleeding gums, I each had epistaxis and vaginal spotting. No transfusion was required for these 4 patients. The mean hospital stay was 4.2 ± 1.5 days. There was no mortality in this study. Conclusion: Dengue illness is a relatively benign self-limiting illness. When the PCs are on the rising trend an in the absence of clinical bleeding, it is reasonably safe to discharge patients when the PCs reach 80 x 10 3 ul -1 , instead of 100 x 10 3 ul -1 . This will shorten each patient's stay by I day, resulting in cost saving and more efficient use of hospital beds.