The degree of chills for risk of bacteremia in acute febrile illness

Purpose Patients with acute febrile illness may experience different degrees of chills. To evaluate the different degrees of chills in predicting risk of bacteremia in patients with acute febrile illness, we performed a single-center prospective observational study. Methods We enrolled consecutive adult patients with acute febrile illness presenting to our emergency department. We defined mild chills as cold-feeling equivalent such as the need of an outer jacket; moderate chills as the need for a thick blanket; and shaking chills as whole-body shaking even under a thick blanket. We estimated risk ratios of the different degrees of chills for bacteremia using multivariable adjusted Poisson regression. Results Of a total 526 patients, 40 patients (7.6%) had bacteremia. There were 65 patients (12.4%) with shaking chills, 100 (19%) with moderate chills, and 105 (20%) with mild chills. By comparing patients with no chills, the risk ratios of bacteremia were 12.1 (95% confidence interval [CI] 4.1-36.2) for shaking chills, 4.1 (95% CI 1.6-10.7) for moderate chills, and 1.8 (95% CI 0.9-3.3) for mild chills. Shaking chills showed a specificity of 90.3% (95% CI 89.2-91.5) and positive likelihood ratio of 4.65 (95% CI 2.95-6.86). The absence of chills showed a sensitivity of 87.5% (95% CI 74.4-94.5) and negative likelihood ratio of 0.24 (95% CI 0.11-0.51). Conclusion Evaluation of the degree of chills is important for estimating risk of bacteremia in patients with acute febrile illness. The more severe degree of chills suggests the higher risk of bacteremia.