Avery et al developed a model for predicting the probability of Lyme meningitis in a child presenting with aseptic meningitis in a region endemic for Lyme disease. The authors are from the Alfred I duPont Hospital for Children in Wilmington, the University of Delaware and Thomas Jefferson University in Philadelphia.
Patient selection: child > 2 years of age
Parameters:
(1) percent mononuclear cells in CSF differential count
(2) duration of headache in days
(3) cranial neuritis
Cranial Neuritis
Points
absent
-2.833
present
0
X =
= (0.026 * (percent mononuclear cells)) + (0.128 * (duration of headache in days)) + (points for cranial neuritis)) - 2.063
where:
• The point assignment for cranial neuritis is the opposite of what is shown in Table 2 but is consistent with the formula n page e4.
• The formula above gives the same probabilities for the data shown in Table 4.
probability of Lyme meningitis =
= 1 / (1 + EXP((-1) * X))
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