PhD thesis - University of Hertfordshire Research Archive

Methods.
The PubMed database (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) was
interrogated to identify citations which contained the Medical Subject
Heading (MeSH) term “Campylobacter” or the text word “Campylobacter” and
which also contained the MeSH term, MeSH subheading or text word
"Epidemiology", but where no fields in the database contained “periodontal”
or “pylori”. The latter statements were included to exclude manuscripts
relating to campylobacters as a cause of periodontal disease (e.g.
Campylobacter rectus) and articles relating to Helicobacter pylori, which was
originally termed Campylobacter pylori. The search results were then limited
to English language articles relating to human subjects.
The titles and abstracts for the resulting citations were then scrutinized and
potential case-control studies on sporadic human Campylobacter infection,
undertaken in developed countries, were identified. Manuscripts were
obtained, read, assessed and categorised. Reference lists were inspected in
order to identify additional studies not found through the PubMed search.
Salient epidemiological characteristics of the investigation and findings were
stored in a bespoke Microsoft Access database.
Simple statistical analyses of the resulting data were undertaken using
Microsoft Excel. Frequencies, percentages and means were calculated
where required. Stata version 10 (Stata Corporation, 1999) was used to
assess factors affecting the number of reported risk factors for infection
identified in case-control studies. Three categorical variables were created.
One compared studies conducted in the eighties with those conducted in the
nineties and those conducted from 2000. A second compared studies
conducted in North America with those conducted in the United Kingdom,
those conducted in the rest of Europe and those conducted in Australasia.
The third compared studies of less than one year duration with those lasting
12 months and with those lasting longer than 12 months. Binary variables
were created to compare those studies where multivariate techniques were
applied with those where they were not and to compare those studies limited
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