Acute meningococcal meningitis: analysis of features of the disease according to the age of 255 patients. Copenhagen Meningitis Study Group.

Clinical and laboratory features of acute meningococcal meningitis according to age were studied in 255 patients. Whereas males accounted for three out of five patients aged 0-4 years, females accounted for three out of four patients older than 50 years of age. All patients had clinical signs of nuchal rigidity and fever. Patients older than 30 years of age had less frequent petechiae (62%) than younger patients (81%). Furthermore, elderly patients above 50 years of age were prone to an obtunded mental state and a prolonged disease course with fever. Without relation to age, 2/3 had purulent meningitis and 2/3 had marked peripheral leucocytosis (> 15 x 10(9) cells/l); 90% of patients had at least one of these findings. The cellular inflammatory response in peripheral blood indicated a bacterial aetiology in > 95% of the cases. More than 80% of children and adults had abnormal CSF biochemical findings, but the level of protein and the glucose ratio (CSF/serum) were positively and negatively correlated to increasing age of the patient, respectively: thus, in children these biochemical markers may be unreliable in the differentiation between a bacterial and non-bacterial aetiology. Thrombocytopenia (< 100.000 x 10(9)/I) was not associated with age, though the lowest platelet count was found in elderly patients. The case fatality rate was 7.5%, but neither age, sex nor sign of septicaemia was associated with fatality. Thrombocytopenia, a lowered coagulation index (< 0.5, factors II, VII, X), a moderate anaemia (haemoglobin < 11 g/dl), an obtunded mental state and a history of convulsions were poor prognostic factors; only anaemia was independently correlated to fatality so this should be considered as an important prognostic marker in the acute phase of meningococcal meningitis.