Differences in Tetanus Antibody Titer between Homeless Patients and General Patients

ABSTRACT

PURPOSE: Homeless patients usually live outside and are therefore frequently exposed to injury and tetanus infection. Thus, after visits to an emergency department (ED) due to injury, homeless patients need to be vaccinated for the prevention of tetanus infection with tetanus immunoglobulin regardless of tetanus antibody titer or previous vaccination history. Because the exact history of previous tetanus vaccination in homeless patients is unclear, the tetanus antibody titer between homeless patients and general patients was assessed. METHODS: Subjects who visited the ED after injury from October 2008 to February 2010 were enrolled. All participants answered questions on age, gender, previous vaccination or prophylaxis history, and military service. The Tetanus Immunoglobulin G ELISA (Enzyme-linked immunosorbent assay) method was used for the analysis of serum samples. Propensity score-matched analysis was used to control for age, gender, previous vaccination or prophylaxis history, and military service. RESULTS: A total of 1325 samples were analyzed. There was 83 samples from homeless patients and 1242 samples from general patients. After matched analysis using the propensity score, 56 subjects were matched. The geometric mean titer of tetanus antibody was 0.204+/-0.392 IU/mL in homeless patients and 0.105+/-0.143 IU/mL in general patients (p=0.078). The proportion of patients with a safe tetanus antibody titer was 66.1 percent of homeless patients and 23.2 percent of general patients (p<0.001). CONCLUSION: Homeless patients had a higher mean titer and a statistically higher proportion had a safe titer compared to general patients.