Background The objective of this study was to estimate the prevalence of he
patitis B virus exposure (HBV) in the population of the Republic of Ireland
, by using oral fluid (saliva) collection by post for hepatitis B anti-core
antibody (anti-HBc). This paper discusses the methodological approach used
and the strategies that were adopted to improve response rates.
Methods The sampling frame used was the Register of Electors for Irish parl
iamentary elections. A multistage stratified cluster sample was taken, and
a total of 962 households were selected nationally. A four-letter approach
was employed for sample collection. Households received an initial letter o
utlining the purpose of the study. This was followed by a letter containing
six swabs for oral fluid collection, along with easy-to-follow instruction
s. Non-respondents received two reminder letters, and were also telephoned
where possible. A telephone helpline was provided. All testing was anonymou
s and unlinked.
Results The study achieved a good household response rate (60.4%), and more
than 98% of the 1738 specimens received were suitable for testing. The pre
valence of anti-HBc in the Irish population was estimated to be 0.51%. The
observed design effect was 1.29.
Discussion From a review of the literature, this is the first study where a
representative sample of a national population was asked to self-collect o
ral fluid samples and return these by post for serological testing. The tec
hnique may have many future applications in epidemiological research.