Predicting the Clinical Outcome of Tetanus: the Tetanus Severity Score

Objectives: To create a new tetanus score and compare it with the Phillips and Dakar scores.

Methods: We used prospectively acquired data from consecutive patients admitted to the Hospital for Tropical Diseases, Ho Chi Minh City, to create the Tetanus Severity Score (TSS) with multivariate logistic regression. We compared the new score with Phillips and Dakar scores by means of resubstituted and prospective data, assessing performance in terms of sensitivity, specificity and area under receiver operator characteristic curves.

Results: Resubstitution testing yielded a sensitivity of 77% (298/385) and a specificity of 82% (1,183/1,437) for the TSS; 89% (342/385) and 20% (281/1,437) for the Phillips score; and 13% (49/385) and 98% (1,415/1,437) for the Dakar score. The TSS showed greatest discrimination with 0.89 area under the receiver operator characteristic curve (95% CI 0.88-0.90); this was 0.74 for the Dakar score and (95% CI 0.71-0.77) and 0.66 for the Phillips score (95% CI 0.63-0.70; P values <0.001). Prospective testing showed 65% (13/20) sensitivity and 91% (210/230) specificity for the TSS; 80% (16/20) and 51% (118/230) for the Phillips score; and 25% (5/20) and 96% (221/230) for the Dakar score. The TSS achieved the greatest area under TSS of 0.89 (95% CI 0.82-0.96), significantly greater than the Phillips score [0.74 (0.6-0.88), P = 0.049] but not the Dakar score [0.80, (0.71-0.90), P = 0.090].

Conclusions: The TSS is the first prospectively developed classification scheme for tetanus and should be adopted to aid clinical triage and management and as a basis for clinical research.