[Prevalence of anti-HAV antibodies and efficacy of pre-vaccine detection at institutions for mentally retarded of the city of Alicante].

OBJECTIVE: The aim of this study was to investigate the prevalence and efficacy of the anti-HAV antibodies detection in institucions for mentally retarded people in the city of Alicante.
DESIGN: Prevalence study.
SETTING: Two institucions for mentally retarded people in the city of Alicante. PARTICIPANTS: One hundred and seven residents and seventy seven in care of them.
MEASUREMENTS AND MAIN RESULTS: We have investigated the anti-HAV antibodies prevalence by enzymeinmunoanalysis of microparticle test. The efficacy of the anti-HAV antibodies detection before the vaccination has been studied by calculating the threshold of prevalence with the following formula: unit cost of detection + (1 - X) x unit cost vaccination anti-HAV negative subjects = unit cost vaccination. RESULTS: The global prevalence of anti-HAV antibodies was 56.5% (95% CI, 49-63.7). The prevalence of the residents was 55.1% (95% CI, 45.2-64.7) and 58.4% in care of them (95% CI, 46.6-69.5). Among the sociodemographic variables evaluated only the age was associated with the prevalence of anti-HAV antibodies (p < 0.001). The unit cost of prevaccination detection of anti-HAV antibodies was calculated as 998 pesetas and the unit cost of the vaccination as 3595, obtaining a prevalence anti-HAV threshold of 27.8%.
CONCLUSIONS: The prevalence of anti-HAV antibodies in this collective studied is similar to the prevalence of anti-HAV antibodies of the spaniard population. The direct vaccination without a previous marker study is recommended to people under the age of 31 in this population group.