Validation of a rapid test to predict tetanus immunity in patients presenting with wounds in an emergency department: a prospective concordance study of 1018 patients:

Introduction In the emergency department, (ED) tetanus prophylaxis (TP) is inadequate in 30–40% of cases, because of patients’ unawareness of their immunization history and physicians’ low compliance with TP recommendations. Purpose Prospective concordance study of a test called tetanus quick stick (TQS) to determine that (1) all patients with a positive TQS are indeed protected and (2) TQS is reproducible by all emergency department care providers. Methods TQS is designed to detect antitoxins in serum or blood at levels above 0.1 and 0.2 IU/mL, respectively. Its outcome was expressed as positive or negative, 20min after using a drop of blood obtained from patients by pricking a finger. It was confronted to serum antitoxin levels measured by enzyme immunoassay with seroprotection defined as more than 0.1 IU/mL. Persons conducting the assays were unaware of TQS outcome. Phase A: training period. 60 nurses and physicians tested each other for TQS. Phase B: reproducibility of TQS performing and reading was then conducted in the first 50 patients. Phase C: after obtaining signed consent, we included all consecutive patients aged Z15 years presenting with fresh (o24 h) wounds, whose tetanus protection was assessed by the two techniques. Endpoints – main endpoint: a false-positive rate near 0. Other: concordance rate of o90% between the two measurements. Results Of 1421 individuals tested, 1018 had both TQS and SAL and were retained for concordance analysis (60A, 50B and 908C). TQS reproducibility between testers was 98%. Sensitivity was 82.83% and specificity 97.32%. False positives and negatives in phases C (N1⁄4908), then AþB (N1⁄4110) were 2.68% versus 0 and 18.09% versus 8.0%, respectively. Conclusions (1) TQS is reliable and can be easily reproduced by ED care providers. (2) TQS is currently the most specific and sensitive of all available tools in predicting in real time tetanus protection of patients presenting in ED with wounds. (3) The outcome of the present study, if confirmed, may be included in new tetanus prophylaxis guidelines.