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

OBJECTIVE

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 1 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 1 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, 1 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.

CONCLUSIONS

Dengue illness is a relatively benign self-limiting illness. When the PCs are on the rising trend and 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 1 day, resulting in cost saving and more efficient use of hospital beds.