Synopsis: The presence of rigors in a febrile child significantly increases the probability of a bacterial infection.
Source: Tal Y, et al. The clinical significance of rigors in febrile children. Eur J Pediatr 1997;156:457-459.
Chills are defined as a sensation of cold that accompa- nies most fevers. A rigor is a profound chill with pilo-erection associated with chattering of the teeth and severe shivering. In adults, rigors have been associated with serious bacterial infections such as bacteremia and pyelonephritis. However, it is not known whether rigors in children are more frequent in bacterial infections than in comparable fevers of other etiologies, especially viral infections. Tal and associates from the B’nai Zion Medical Center in Israel compared 100 hospitalized febrile children who experienced rigors with 334 hospitalized, febrile, matched control children without rigors.
All 434 children underwent appropriate diagnostic studies. The control group was matched for age, sex, degree of fever, and the Yale Toxicity Score.1 The children ranged in age from 6 months to 16 years with an average of 6.4 years. All children had clinical examinations by one of four pediatricians. All had CBC, ESR, urinalysis, chest roentgenogram, and cultures of blood, urine, and stool. Rigors were either directly observed by medical personnel or reported by a care giver.
Based upon laboratory and clinical findings, both rigor patients and controls were assigned to three groups: 1) Proven bacterial infection; 2) presumed bacterial infection; and 3) presumed non-bacterial infection. Proven bacterial infections were defined by positive blood, urine, or stool cultures. Presumed bacterial infections were defined as those conditions that are often associated with a bacterial etiology (although a viral etiology could not be definitely excluded) and included roentgenographically demonstrated pneumonia and otitis media. Presumed non-bacterial infections included acute febrile episodes where the clinical examination, x-rays, or cultures did not indicate a probable bacterial etiology.
Sixty-seven percent of the children with rigors fell into the proven or presumed bacterial infection group, compared to 51% of the control group (P < 0.005). With regard to positive blood or urine cultures, the rigor group was 2.5% higher than the controls, and the difference was even more pronounced for positive blood cultures, which were 4.2% more common in the patients with rigor. In children older than 1 year, positive blood cultures (mostly due to pneumococci) were 13 times more common in the group of children with rigors.
Tal et al conclude that even though the absence of rigors in a febrile child does not exclude a bacterial infection, their presence significantly increases the probability of a bacterial infection, and this should be considered by clinicians in their assessment of a febrile child.
COMMENT BY PAUL McCARTHY, MD, FAAP
One of the most frequent acute problems that we face as clinicians is trying to assess whether fever in a child has a relatively trivial or a potentially serious etiology. Experienced clinicians intuitively use a "gestalt"how a febrile child looks, acts, and reactsto make their judgment on how "sick the child really is." These types of clinical observations have been codified into assessment systems such as our "Yale Toxicity Score," which has been invaluable for teaching our housestaff a logical approach to evaluation of a febrile child.1,2
Most physicians believe intuitively that rigors that occur at the onset of acute high fevers may be an indication of bacterial infections. This study provides some data to support this belief. Children with rigors were much more likely to have proven bacterial infection. Interestingly, in children older than 1 year, rigors were frequently associated with occult pneumococcal bacteremia.
The only significant laboratory finding was the more frequent presence of "bandemia" of greater than 1500/mm3 in children with proven bacterial infections. The combination of rigors plus bandemia further increased the likelihood of a bacterial etiology.
As noted by Tal et al, although a history of rigors significantly increases the likelihood of a bacterial infection, their absence does not exclude such an infection. (Dr. McCarthy is Professor of Pediatrics and Chief of the Division of General Pediatrics, Yale University.)
References
1. McCarthy PL, et al. Definition of valid and reliable observation scales to identify serious illness in febrile children. Pediatrics 1982;70:802-809.
2. McCarthy PL, et al. Predictive values of abnormal physical examination findings in ill-appearing and well-appearing febrile children. Pediatrics 1985;76: 167-171.
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