Differentiating COVID-19 and dengue from other febrile illnesses in co-epidemics: Development and internal validation of COVIDENGUE scores

Abstract

Background. In a retrospective cohort study, we previously distinguished the factors associated with coronavirus 2019 (COVID-19) or dengue from those associated with other febrile illnesses (OFIs). In this study, we developed a scoring system to discriminate both infectious diseases. Methods. Predictors of both infections were sought using multinomial logistic regression models (OFIs as controls) in all subjects suspected of COVID-19 who attended the SARS-CoV-2 testing center of Saint-Pierre teaching hospital, Reunion Island, between March 23 and May 10, 2020. Two COVIDENGUE scores were developed and internally validated by bootstrapping for predicting each infection after weighting the odd ratios according to a predefined rule. The discriminative ability of each score was assessed using the area under the receiver operating characteristic curve (AUC). Their calibration was assessed using goodness-of-fit statistics. Results. Over 49 days, 80 COVID-19, 60 non-severe dengue and 872 OFI cases were diagnosed. The translation of the best fit model yielded two COVIDENGUE scores composed of 11 criteria: contact with a COVID-19 positive case (+3 points for COVID-19; 0 point for dengue), return from travel abroad within 15 days (+3/-1), previous individual episode of dengue (+1/+3), active smoking (-3/0), body ache (0/+5), cough (0/-2), upper respiratory tract infection symptoms (-1/-1), anosmia (+7/-1), headache (0/+5), retro-orbital pain (-1/+5), and delayed presentation (>3 days) to hospital (+1/0). The AUC was of 0.79 (95%CI 0.76-0.82) for COVID-19 score and of 0.88 (95%CI 0.85-0.90) for dengue score. Calibration was satisfactory for COVID-19 score and excellent for dengue score. For predicting COVID-19, sensitivity was of 97% at the 0-point cut-off and specificity approximated 99% at the 10-point cut-off. For predicting dengue, sensitivity approximated 97% at the 3-point cut-off and specificity 98% at the 11-point cut-off. Conclusions. In conclusion, the COVIDENGUE scores proved discriminant to differentiate COVID-19 and dengue from other febrile illnesses in the context of SARS-CoV-2 testing center during a co-epidemic. Further studies are needed to validate or refine these scores in other settings.