Discovery and Validation of Prognostic Biomarker Models to Guide Triage among Adult Dengue Patients at Early Infection.
BACKGROUND
Dengue results in a significant public health burden in endemic regions. The World Health Organization (WHO) recommended the use of warning signs (WS) to stratify patients at risk of severe dengue disease in 2009. However, WS is limited in stratifying adult dengue patients at early infection (Day 1-3 post fever), who require close monitoring in hospitals to prevent severe dengue. The aim of this study is to identify and validate prognostic models, built with differentially expressed biomarkers, that enable the early identification of those with early dengue infection that require close clinical monitoring.


METHODS
RNA microarray and protein assays were performed to identify differentially expressed biomarkers of severity among 92 adult dengue patients recruited at early infection from years 2005-2008. This comprised 47 cases who developed WS after first presentation and required hospitalization (WS+Hosp), as well as 45 controls who did not develop WS after first presentation and did not require hospitalization (Non-WS+Non-Hosp). Independent validation was conducted with 80 adult dengue patients recruited from years 2009-2012. Prognostic models were developed based on forward stepwise and backward elimination estimation, using multiple logistic regressions. Prognostic power was estimated by the area under the receiver operating characteristic curve (AUC).


RESULTS
The WS+Hosp group had significantly higher viral load (P<0.001), lower platelet (P<0.001) and lymphocytes counts (P = 0.004) at early infection compared to the Non-WS+Non-Hosp group. From the RNA microarray and protein assays, the top single RNA and protein prognostic models at early infection were CCL8 RNA (AUC:0.73) and IP-10 protein (AUC:0.74), respectively. The model with CCL8, VPS13C RNA, uPAR protein, and with CCL8, VPS13C RNA and platelets were the best biomarker models for stratifying adult dengue patients at early infection, with sensitivity and specificity up to 83% and 84%, respectively. These results were tested in the independent validation group, showing sensitivity and specificity up to 96% and 54.6%, respectively.


CONCLUSIONS
At early infection, adult dengue patients who later presented WS and require hospitalization have significantly different pathophysiology compared with patients who consistently presented no WS and / or require no hospitalization. The molecular prognostic models developed and validated here based on these pathophysiology differences, could offer earlier and complementary indicators to the clinical WHO 2009 WS guide, in order to triage adult dengue patients at early infection.
Infectious Disease, Genome Institute of Singapore, Singapore, Singapore.|Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.|Communicable Diseases Center, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore.
Junxiong
J
Pang
Infectious Disease, Genome Institute of Singapore, Singapore, Singapore.|Department of Medicine Solna, Unit of Infectious Diseases, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Anna
A
Lindblom
Infectious Disease, Genome Institute of Singapore, Singapore, Singapore.|Department of Medicine Solna, Unit of Infectious Diseases, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.|Unit for Highly Pathogenic Viruses, Public Health Agency of Sweden, Stockholm, Sweden.
Thomas
T
Tolfvenstam
Communicable Diseases Center, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore.
Tun-Linn
TL
Thein
Infectious Disease, Genome Institute of Singapore, Singapore, Singapore.
Ahmad Nazri Mohamed
AN
Naim
Infectious Disease, Genome Institute of Singapore, Singapore, Singapore.
Ling
L
Ling
Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, Singapore, Singapore.
Angelia
A
Chow
Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.|Communicable Diseases Center, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore.
Mark I-Cheng
MI
Chen
Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, Singapore, Singapore.|DSO National Laboratories, Singapore, Singapore.
Eng Eong
EE
Ooi
Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.|Communicable Diseases Center, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore, Singapore.|Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
Yee Sin
YS
Leo
Infectious Disease, Genome Institute of Singapore, Singapore, Singapore.|Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.|London School of Hygiene & Tropical Medicine, London, United Kingdom.
Martin L
ML
Hibberd
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis* / Q000378:metabolism; D016022:Case-Control Studies; D003715:Dengue / Q000145:classification / Q000175:diagnosis* / Q000235:genetics / Q000628:therapy; D042241:Early Diagnosis; D005260:Female; D020869:Gene Expression Profiling; D006760:Hospitalization; D006801:Humans; D008297:Male; D046228:Microarray Analysis; D008875:Middle Aged; D011379:Prognosis; D012680:Sensitivity and Specificity; D014218:Triage / Q000379:methods*; D055815:Young Adult
D015415:Biomarkers