Risk scores for outcome in bacterial meningitis: Systematic review and external validation study

OBJECTIVES: To perform an external validation study of risk scores, identified through a systematic review, predicting outcome in community-acquired bacterial meningitis. METHODS: MEDLINE and EMBASE were searched for articles published between January 1960 and August 2014. Performance was evaluated in 2108 episodes of adult community-acquired bacterial meningitis from two nationwide prospective cohort studies by the area under the receiver operating characteristic curve (AUC), the calibration curve, calibration slope or Hosmer-Lemeshow test, and the distribution of calculated risks. FINDINGS: Nine risk scores were identified predicting death, neurological deficit or death, or unfavorable outcome at discharge in bacterial meningitis, pneumococcal meningitis and invasive meningococcal disease. Most studies had shortcomings in design, analyses, and reporting. Evaluation showed AUCs of 0.59 (0.57-0.61) and 0.74 (0.71-0.76) in bacterial meningitis, 0.67 (0.64-0.70) in pneumococcal meningitis, and 0.81 (0.73-0.90), 0.82 (0.74-0.91), 0.84 (0.75-0.93), 0.84 (0.76-0.93), 0.85 (0.75-0.95), and 0.90 (0.83-0.98) in meningococcal meningitis. Calibration curves showed adequate agreement between predicted and observed outcomes for four scores, but statistical tests indicated poor calibration of all risk scores. INTERPRETATION: One score could be recommended for the interpretation and design of bacterial meningitis studies. None of the existing scores performed well enough to recommend routine use in individual patient management