Development of score models for severe course risk assessment of febrile form of tick-borne encephalitis

   Background. There is no current generally accepted classification and clinical approaches to assess the clinical course severity of tick-borne encephalitis.   The aim is to develop models for the quantitative severity scores of the febrile form of tick-borne encephalitis using the most informative predictors.   Materials and methods. In accordance with clinical criteria of the height and duration of fever, two groups of 9 and 30 patients (52.2 ± 4.3 and 49.5 ± 3.9 years old) with severe and non-severe febrile form of tick-borne encephalitis were formed. The study design was a retrospective case-control study. Statistical significance assessment of variables was carried out using the chi-square test. The odds ratios were also calculated. The development of logistic regression models was carried out using Statistica 12.0 modules.   Results. A questionnaire of febrile form of tick-borne encephalitis severity score was developed using the height of fever and 11 most informative clinical predictors including arthralgia, chills, sleep disturbance, dizziness, orbital pain, nausea, photophobia, myalgia, severe headache, vomiting and meningism. To predict the severe clinical course of febrile form of tick-borne encephalitis, two logistic regression models were developed with or without severity score assessment of fever syndrome (coefficients α and β were –12.13 and 0.94 and –5.78 and 0.75 for models 1 and 2, respectively). Models 1 and 2 demonstrated a high predicted probability for cut-off values equal to 14 and 9 points and excellent quality of prediction test (AUC are equal to 0.99 and 0.98, respectively).   Conclusions. The models of severity score demonstrated high predicted probabilities to predict severe clinical course of febrile form of tick-borne encephalitis, which can be used in clinical practice and for scientific purposes.