The specimens and questionnaires were anonymous, and feedback was given to all participants of the study, including their results. All unprotected participants were advised to be vaccinated against hepatitis A. Data are presented as medians and frequencies. The performance of the laboratory tests with the collected oral fluid samples was determined by comparing the sensitivity, specificity, and positive and negative predictive values and their respective 95% confidence intervals EGFR inhibitor (95% CI) with the serum results, which
were used as a gold standard control. The linear and weighted kappa (k) statistic was used to evaluate the rate of agreement between the oral fluid and serum anti-HAV antibody status for each device used. According to the strength of the agreement, the k value was interpreted as follows [16]: <20%: poor; 21–40%: fair; 41–60%: moderate; 61–80%: good; and 81–100%: very good. To compare proportions, the Chi-square (χ2) test for independence with selleck screening library Yate’s continuity correction, χ2 for trend, and Fisher’s exact test
(when appropriate) were used. The Spearman’s coefficient of rank correlation (rs) was used to evaluate the degree of the relationship between the values of color intensity on the colorimetric scale obtained after using the oral fluid collection devices. A two-tailed p < 0.05 was considered statistically significant. All analyses were performed with MedCalc for Windows, version
8.1.0.0 (MedCalc Software, Mariakerke, Belgium), and GraphPad InStat version 3.05 (GraphPad Software, CA, USA) software. The optimal oral fluid dilution for detecting anti-HAV antibodies in the ImmunoComb® II HAVAb was determined using matched samples from the optimization panel. Among the 30 individuals with natural immunity to HAV, oral fluid samples collected by OraSure® and Salivette® devices presented concordant results with those from serum samples until a 1:25 dilution. However, false-negative results were observed after because the 1:5 dilution when the ChemBio® device was used. For the 25 HAV-vaccinated individuals, all of the diluted samples presented false-negative results, irrespective of the oral fluid collection device used. False-positive results were not observed in the group of 35 individuals who were non-reactive for anti-HAV antibodies. Based on these findings, the detection of anti-HAV antibodies by all of the devices was optimal when undiluted oral fluids were used; the evaluation of other parameters (temperature, incubation time, etc.) was not required to optimize these samples. The rate of agreement between the oral fluid and serum anti-HAV antibody status for each device was evaluated for each group of individuals.