Source: Thailand Medical News  Oct 28, 2019  3 years ago
Singaporean Medical Researchers From NUS Find That Elderly Dengue Patients Face More Difficult Platelet Recovery
Singaporean Medical Researchers From NUS Find That Elderly Dengue Patients Face More Difficult Platelet Recovery
Source: Thailand Medical News  Oct 28, 2019  3 years ago
A recent study at National University Of Singapore  led by researchers from National University Hospital, Singapore General Hospital and Tan Tock Seng Hospital found that old age and lower white cell counts are significant risk factors for poor platelet recovery among dengue patients with thrombocytopaenia.

According to Dr Yee-Sin Leo from the Department of Medicine, National University Of Singapore in a comment to Thailand Medical News, “We identified several independent predictors of poor platelet recovery in dengue patients. Our findings highlight the impact of ageing and, potentially, immunosenescence in dengue infection.”

A total of 362 dengue patients participated in the study, of which 188 were randomly assigned to prophylactic platelet transfusion, while 181 received supportive care alone. Nine patients did not have day 2 platelet counts and were excluded. Of the remaining 360 patients, 43.9 percent (n=158) had poor platelet recovery, defined as having a platelet count of ≤20,000/µL by day 2.

Medical analysis according to treatment groups showed that most of the dengue patients with poor platelet recovery did not receive a platelet transfusion (56.3 percent vs 32.3 percent). In unadjusted analysis, age (p=0.0076), white cell counts (p=0.0007), serum creatinine (p=0.0108) and the number of days with illness at study enrolment (p=0.0002) were identified as significant predictors of poor platelet recovery.

After controlling for transfusion, only age (adjusted odds ratio [OR], 1.03, 95 percent CI, 1.01–1.05; p=0.0041), white cell count (adjusted OR, 0.79, 0.70–0.90; p=0.0002) and day of illness at study entry (adjusted OR, 0.67, 0.53–0.85; p=0.0009) remained significant risk factors for poor recovery.

The researchers said, “Although thrombocytopaenia and platelet dysfunction have been well described in dengue, the pathophysiology has not been well studied. Some proposed mechanisms included peripheral platelet destruction, platelet sequestration and virus-induced bone marrow suppression.( *Note 1)

This was further complicated in older patients with dengue, who had been shown to suffer from greater disease severities and atypical presentations. Immunosenescence might help account for these.(*Note 2)

The researchers added, “Immunosenescence in the older population may result in poorer bone marrow and other physiological reserves, which may account for the poor platelet recovery observed in this analysis in the older age group,”
The study was a posthoc analysis of the Adult Dengue Platelet (ADEPT) study, an open-label, randomized trial conducted on patients in Singapore and Malaysia. The current study sample comprised the as-treated population in the original trial with available day 2 platelet count data.

This time point was chosen following the observation in ADEPT that 25.3 percent of patients required a second transfusion to ma intain a platelet count above 20 000 per μL on Day 2, but no patients required transfusion on subsequent days.

Further work is needed to examine the pathophysiology and role of thrombocytopaenia and the risk of clinical bleeding in severe dengue,” they said. “Further studies evaluating the role of platelet transfusions in patients with severe dengue will be valuable, but sample sizes may be hard to attain."

The overall incidence of dengue, as well as the explosive outbreaks of dengue, has been increasing dramatically over the last several years. One study estimates that approximately 390 million dengue infections occur per year, with 96 million of these presenting clinically. South-East Asia is one of the prime locations for dengue infections due to the equatorial climate that is conducive for mosquito breeding.

Reference: Predictors and Clinical Outcomes of Poor Platelet Recovery in Adult Dengue With Thrombocytopenia: A Multicenter, Prospective Study, Sophia Archuleta, Po Ying Chia, Yuan Wei, Sharifah F Syed-Omar, Jenny G Low, Helen M Oh, Dale Fisher, Sasheela S L Ponnampalavanar, Limin Wijaya, Adeeba Kamarulzaman, Lucy C S Lum, Paul A Tambyah, Yee-Sin Leo, David C Lye, Clinical Infectious Diseases, ciz850,, Published: 18 October 2019
Note 1 . [Viral Immunol 2006;19:127-132; Am J Trop Med Hyg 2002;66:435-441; Blood 1989;74:1235-1240]

Note 2: [PLoS Negl Trop Dis 2014;8:e2777]


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