Assessment of tetanus immunity status by tetanus quick stick and anamnesis: a prospective double blind study

In patients with wounds admitted to Emergency Departments (ED) acquiring tetanus vaccination history by interview is very unreliable. Protected patients may receive unnecessary prophylaxis and unprotected nothing. Aim of the study was to evaluate tetanus immunity status comparing the traditional anamnestic method with the Tetanus Quick Stick (TQS), a rapid immunochromatographic test.

A double-blind prospective study was carried out in the ED of the 1,000 bed teaching hospital Umberto I in Rome. Adult patients (≥18) with wounds attending at the ED were randomly included. Tetanus immunity status was evaluated by healthcare workers (HCWs) comparing the TQS test with the anamnesis. TQS test was performed by a trained HCW and afterwards the anamnesis about tetanus immunity status was collected by another HCW unaware of the TQS result. Also cost analysis was carried out.

Overall 400 patients (242 males and 158 females) were included, mean age was 46.7 ± 20.2 years (median 44 range 18 - 109), 304 (76.0%) were italians and 96 foreigners (24.0%). Overall, 209 (52.2%) resulted TQS +, and protective immunity level was associated to lower mean age (40.1 ± 16.8 vs 53.8 ± 21,1; p<0,01). Using the anamnestic method 336 (84.0%) patients resulted "unprotected", 52 (13.0%) "partially unprotected" and 12 (3.0%) "completely protected". TQS test results showed that 154 (45.8%) out of 336 "unprotected" and 45 (86.5%) out of 52 "partially unprotected" actually had a protective antibody level. Finally two (16.7%) out of 12 "completely protected" group presented a non protective antibody level. Following only the anamnestic method 201 (50.0%) patients would have received some inappropriate treatment. Adopting TQS test in all patients would also be cost-effective saving € 1.95/patient. As tetanus immunity is inversely related to age, for <51 years old patients unnecessary treatment would have been avoided in 57.1% of patients, with a mean reduction per patient of € 7.50/patient with the TQS vs. € 12.69/patient without.

The study showed that tetanus protective immunity prevalence among adult patients attending our ED is about 50% and is mainly influenced by class age. TQS use allowed to reduce drastically inappropriate tetanus vaccine and immunoglobulins booster treatment. Also TQS use reduced costs.