Fig 1.
Epidemiological characteristics of EVD outcome.
(A) Kaplan-Meier survival analysis of patients in the ETC according to their EVD status. (B) Mortality among EVD(-) and EVD(+) admissions according to gender. (C) Average age of death among EVD(-) and EVD(+) patients. (D) Mortality rate across age groups in EVD(-) and EVD(+) cohorts. Dotted lines represent the average mortality rate across all ages in the cohort. Statistics in (C) calculated by unpaired t test *: p<0.05, **: p<0.005, ***: p<0.001, ns: not significant.
Fig 2.
Prognostic potential of clinical signs and symptoms recorded at and after admission.
(A) Prevalence of clinical characteristics at triage amongst EVD(+) patients who either survived or died, ranked according to the prevalence in fatal outcomes. Rankings from 1–19 are listed above each bar: black for the outcome of death and grey for survival. (B) Differences in symptom prevalence between EVD survivors and those who died. Positive values are more prevalent in fatal outcomes. Negative values are more prevalent in survivors.
Table 1.
Association of clinical and laboratory characteristics to EVD mortality.
Fig 3.
Prognostic value of Ebola virus load (Ct value).
(A) Distribution of Ct values1 for EVD(+) patients considered to have a high viral load (Ct ≤ 20) and low viral load (Ct > 20). (B) Ct value distribution across age in the EVD(+) cohort. The red line plots the fractional polynomial prediction of the Ct value. (C) Ct values amongst survivors and fatalities in the EVD(+) cohort. (D) Kaplan-Meier survival analysis of EVD(+) patients according their Ebola virus loads, either considered as high viral (Ct ≤ 20) or low viral load (Ct > 20). 1 Ct values represent Ebola-specific qRT-PCR results (inversely proportional to the viral load). Statistics in (C) calculated by unpaired t test *: p<0.05, **: p<0.005, ***: p<0.001, ns: not significant.
Fig 4.
Impact of EVD referral sensitivity on diagnosis and patient outcome.
(A) Mortality rate for EVD(+) patients who were referred “early” (within 3 days of reported symptom onset) or “late” (after 3 days of symptom onset). (B) Cycle threshold (Ct) values1 among early and late EVD(+) referrals. (C) Probability of death according the referral time corrected for Ct value. (D) Probability of death according the number of days spent in the ETC. The average number of days spent in the ETC for patients with fatal or survival outcomes are indicated in colour. (E) Mean referral time of EVD(+) patients according to quarantine (Qt) status. 1 Ct values represent Ebola-specific qRT-PCR results (inversely proportional to the viral load). Statistics in (A, B and E) calculated by unpaired t test *: p<0.05, **: p<0.005, ***: p<0.001, ns: not significant
Fig 5.
Impact of malaria co-infection on patient outcome.
(A) Probability of malaria infection across age for EVD(-) and EVD(+) cohorts. (B) Mortality rates among EVD(-) and EVD(+) cohorts according to the presence of malaria infection. (C) Ct value1 among EVD(+) patients co-infected or not by malaria. (D) Probability of death among EVD(+) patients infected or not by malaria according to EVD Ct value1. 1 Ct values represent Ebola-specific qRT-PCR results (inversely proportional to the viral load). Statistics in (C) calculated by unpaired t test. *: p<0.05, **: p<0.005, ***: p<0.001, ns: not significant
Fig 6.
Derivation of prognostic scoring system for EVD outcome.
The sensitivity and specificity of predicting mortality in EVD(+) patients using the scoring system developed with clinical parameters collected (A) at triage or (B) daily during the admission of the patient at the ETC. The area under the receiver-operator characteristic (ROC) curve represents the discriminative power of each score. (C-D) Sensitivity (green) and specificity (blue) according to the score points of (C) the triage score and (D) the daily score. Prevalence of survivors and those with fatal outcome are displayed as bar graphs and risk category cut-offs are shown as vertical lines. (E) Percentage of survivors and patients with fatal outcome classified in each risk category of the triage EVD mortality score and the (F) daily EVD mortality score.
Fig 7.
Scorecards to extrapolate the Ebola severity risk.
Ebola Virus disease severity risk calculated at (A) triage and (B) after triage. Full page printable templates of these scorecards can be found in the supplementary information (S4 and S5 Figs).
Table 2.
Internal validation of EVD prognostic scores.