VALIDATION OF A CLINICAL-PREDICTION RULE FOR THE DIFFERENTIAL-DIAGNOSIS OF ACUTE MENINGITIS

Objective: To attempt to validate a previously reported clinical predi ction rule derived to assist in distinguishing between acute bacterial meningitis and acute viral meningitis. Design: Retrospective chart re view of patients treated at five hospitals between 1981 and 1990. The criterion standard for bacterial meningitis was a positive cerebrospin al fluid (CSF) or blood culture or a positive test for bacterial antig en in the CSF. For viral meningitis, the criterion standard was a posi tive viral culture from CSF, stool, or blood or a discharge diagnosis of viral meningitis with no other etiology evident. Setting: Two Depar tment of veterans affairs (VA) hospitals, two county hospitals, and on e private hospital, each affiliated with one of two medical schools. P atients: all persons aged more than 17 years who were hospitalized ove r a ten-year period at one of five academically affiliated hospitals f or the management of acute meningitis. Measurements and main results: Sixty-two cases of bacterial meningitis and 98 cases of viral meningit is were confirmed. With all patients included, the discriminatory powe r of the model as measured by the area under the receiver operating ch aracteristic curve (AUC) was 0.977 (95% CI, 0.957-0.997), compared wit h the AUC of 0.97 in the derivation set of the original publication. T he AUCs (95% CIs) for data subsets were: Dallas cases 0.994 (0.986-1.0 ), Milwaukee cases 0.912 (0.834-0.990); ages 18-39 years 0.952 (0.892- 1.0), ages 40-59 years 0.99 (0.951-1.0), and age greater than or equal to 6O years 0.955 (0.898-1.0). Conclusions: The authors conclude that the clinical prediction rule proved robust when applied to a geograph ically distinct population comprised exclusively of adults. There was sustained performance of the model when applied to cases from each cit y and from three age strata. Prospective validation of this prediction rule be necessary confirm its utility in clinical practice.