Reviewer's report
 Helicobacter pylori (H pylori) infection in South-East Europe: the changing prevalence during a Title:
ten-year period and its antigenic profile.
Authors:
Periklis Apostolopoulos (periklisapo@yahoo.com )
Irene Vafiadis (i.vafiadis@grmedia.gr )
Michael Tzivras (pola@med.uoa.gr )
Dimitrios Kourtessas (akorba@med.uoa.gr )
Nicolaos Katsilambros (laennec@techlink.gr )
Athanasios Archimandritis (aarchim@hotmail.com )
 1  29 Nov 2001 Version: Date:
 Dr Hazel Mitchell Reviewer:
 A paper whose findings are important to those with closely related research interests Level of interest:
 Unable to decide on acceptance or rejection until the authors have responded Advice on publication:
to the compulsory revisions
MAJOR Comments 
Introduction 
1. Following the discussion of the cohort phenomenon a more detailed introduction into the relevance of
CagA and VacA is required. 
Materials and Methods 
1. It is stated that "the socioeconomic and educational profile of the patients could be considered 
roughly similar in both groups (87 and 97), taking of course into consideration.............last decade". Given that socioeconomic status is a critical factor in the acquisition of H. pylori what evidence is there 
to support this view? This statement must be clarified. 
2. Were the patient groups (87 and 97) attending the gastroenterology clinic symptomatic and did they all undergo endoscopy? - This must be stated. 
3. What percentage of each of the patient groups (87 and 97) was diagnosed with non-ulcer dyspepsia, 
peptic ulcer disease and gastric cancer? Given the strong association between H. pylori and both ulcer 
disease and cancer, the presence in one patient group (87 or 97) of more diseased subjects may have biased the data. 4. How were the 62H. pylori IgG positive subjects used for examination of the antigenic profile of H. 
pylori chosen? Randomly? Otherwise? 
5. What were the main immunogenic proteins present in the ELISA antigen? And what biochemical procedure was used to enrich these? 6. Was the sensitivity and specificity of the ELISA calculated on the patient groups examined in this 
study or a previous study? Details should be given or a reference. 
7. What are the antigens represented on the Immunoblot Helicobacter pylori IgG? 
8. What is the sensitivity and specificity of this Imunoblotting kit? 
Results 
1. In the text section on "the prevalence of antibodies in O-87 and O-97 groups of patients" too much 
information is provided on the prevalence of infection in different age groups. This information can be 
read in Table1 and visualised in Figure 1. 2. The requirement for tables 2 and 3 are questionable. 
3. On page 9, line 3 the authors state that "The pick of H. pylori seroprevalence differs by one decade" - 
This should read 'The peak of .... 
Discussion 
1. The authors state that provided the ELISA used had of 87% sensitivity and 94% specificity the results
reflect satisfactorily the H. pylori infection rate". Does this infer that they question the sensitivity and 
specificity of the ELISA? 2. The finding that no difference existed in the prevalence of H pylori in the patient group (97) as compared with that in the blood donor group (97) is very unusual. The majority of studies show a 
significantly higher prevalence of infection in symptomatic subjects as compared with asymptomatic 
blood donors. The authors should comment upon this. 3. Although a higher prevalence of H. pylori infection was found in the 87 patient group as compared 
with that in the 97 patient group it is possible that this difference may relate to confounding factors. 
Firstly differences in the socioeconomic status between the year groups (87 and 97) may have 
contributed to the higher prevalence in 1987 and secondly, differences in the prevalence of H. pylori related diseases in the two groups might also have contributed (see comments 1-3 Materials and Methods above). 
4. The argument made by the authors in relation to the cohort phenomenon on Page 10 is circuitous. 
As paired sera were not collected then no comment can be made regarding the acquisition or loss of H. 
pylori. The finding that a higher prevalence of infection is present in the 87 group may be suggestive of 
a cohort phenomenon however again this is not definitive. What is meant by "mainly support". 
5. The authors state on Page 11 that their data suggests that CagA and/or VacA status are not the only 
factors that influence gastric cancer rates. Although this is correct it is certainly not the first study to demonstrate this point. Indeed there are numerous papers in the literature over many years that demonstrate this point. The authors should refer to at least one or more of these. 
6. As stated above it is now quite clear that the development of gastric cancer is multifactorial and thus 
the final sentence of the manuscript is redundant. 
Competing interests:
None declared.
Reviewer's report
 Helicobacter pylori (H pylori) infection in South-East Europe: the changing prevalence during a Title:
ten-year period and its antigenic profile.
Authors:
Periklis Apostolopoulos (periklisapo@yahoo.com )
Irene Vafiadis (i.vafiadis@grmedia.gr )
Michael Tzivras (pola@med.uoa.gr )
Dimitrios Kourtessas (akorba@med.uoa.gr )
Nicolaos Katsilambros (laennec@techlink.gr )
Athanasios Archimandritis (aarchim@hotmail.com )
 1  29 Nov 2001 Version: Date:
 Dr Hazel Mitchell Reviewer:
 A paper whose findings are important to those with closely related research interests Level of interest:
 Unable to decide on acceptance or rejection until the authors have responded Advice on publication:
to the compulsory revisions
MAJOR Comments 
Introduction 
1. Following the discussion of the cohort phenomenon a more detailed introduction into the relevance of
CagA and VacA is required. 
Materials and Methods 
1. It is stated that "the socioeconomic and educational profile of the patients could be considered 
roughly similar in both groups (87 and 97), taking of course into consideration.............last decade". Given that socioeconomic status is a critical factor in the acquisition of H. pylori what evidence is there 
to support this view? This statement must be clarified. 
2. Were the patient groups (87 and 97) attending the gastroenterology clinic symptomatic and did they all undergo endoscopy? - This must be stated. 
3. What percentage of each of the patient groups (87 and 97) was diagnosed with non-ulcer dyspepsia, 
peptic ulcer disease and gastric cancer? Given the strong association between H. pylori and both ulcer 
disease and cancer, the presence in one patient group (87 or 97) of more diseased subjects may have biased the data. 4. How were the 62H. pylori IgG positive subjects used for examination of the antigenic profile of H. 
pylori chosen? Randomly? Otherwise? 
5. What were the main immunogenic proteins present in the ELISA antigen? And what biochemical procedure was used to enrich these? 6. Was the sensitivity and specificity of the ELISA calculated on the patient groups examined in this 
study or a previous study? Details should be given or a reference. 
7. What are the antigens represented on the Immunoblot Helicobacter pylori IgG? 
8. What is the sensitivity and specificity of this Imunoblotting kit? 
Results 
1. In the text section on "the prevalence of antibodies in O-87 and O-97 groups of patients" too much 
information is provided on the prevalence of infection in different age groups. This information can be 
read in Table1 and visualised in Figure 1. 2. The requirement for tables 2 and 3 are questionable. 
3. On page 9, line 3 the authors state that "The pick of H. pylori seroprevalence differs by one decade" - 
This should read 'The peak of .... 
Discussion 
1. The authors state that provided the ELISA used had of 87% sensitivity and 94% specificity the results
reflect satisfactorily the H. pylori infection rate". Does this infer that they question the sensitivity and 
specificity of the ELISA? 2. The finding that no difference existed in the prevalence of H pylori in the patient group (97) as compared with that in the blood donor group (97) is very unusual. The majority of studies show a 
significantly higher prevalence of infection in symptomatic subjects as compared with asymptomatic 
blood donors. The authors should comment upon this. 3. Although a higher prevalence of H. pylori infection was found in the 87 patient group as compared 
with that in the 97 patient group it is possible that this difference may relate to confounding factors. 
Firstly differences in the socioeconomic status between the year groups (87 and 97) may have 
contributed to the higher prevalence in 1987 and secondly, differences in the prevalence of H. pylori related diseases in the two groups might also have contributed (see comments 1-3 Materials and Methods above). 
4. The argument made by the authors in relation to the cohort phenomenon on Page 10 is circuitous. 
As paired sera were not collected then no comment can be made regarding the acquisition or loss of H. 
pylori. The finding that a higher prevalence of infection is present in the 87 group may be suggestive of 
a cohort phenomenon however again this is not definitive. What is meant by "mainly support". 
5. The authors state on Page 11 that their data suggests that CagA and/or VacA status are not the only 
factors that influence gastric cancer rates. Although this is correct it is certainly not the first study to demonstrate this point. Indeed there are numerous papers in the literature over many years that demonstrate this point. The authors should refer to at least one or more of these. 
6. As stated above it is now quite clear that the development of gastric cancer is multifactorial and thus 
the final sentence of the manuscript is redundant. 
Competing interests:
None declared.
Please review this paper.
user
Reviewer's report
 Helicobacter pylori (H pylori) infection in South-East Europe: the changing prevalence during a Title:
ten-year period and its antigenic profile.
Authors:
Periklis Apostolopoulos (periklisapo@yahoo.com )
Irene Vafiadis (i.vafiadis@grmedia.gr )
Michael Tzivras (pola@med.uoa.gr )
Dimitrios Kourtessas (akorba@med.uoa.gr )
Nicolaos Katsilambros (laennec@techlink.gr )
Athanasios Archimandritis (aarchim@hotmail.com )
 1  29 Nov 2001 Version: Date:
 Dr Hazel Mitchell Reviewer:
 A paper whose findings are important to those with closely related research interests Level of interest:
 Unable to decide on acceptance or rejection until the authors have responded Advice on publication:
to the compulsory revisions
MAJOR Comments 
Introduction 
1. Following the discussion of the cohort phenomenon a more detailed introduction into the relevance of
CagA and VacA is required. 
Materials and Methods 
1. It is stated that "the socioeconomic and educational profile of the patients could be considered 
roughly similar in both groups (87 and 97), taking of course into consideration.............last decade". Given that socioeconomic status is a critical factor in the acquisition of H. pylori what evidence is there 
to support this view? This statement must be clarified. 
2. Were the patient groups (87 and 97) attending the gastroenterology clinic symptomatic and did they all undergo endoscopy? - This must be stated. 
3. What percentage of each of the patient groups (87 and 97) was diagnosed with non-ulcer dyspepsia, 
peptic ulcer disease and gastric cancer? Given the strong association between H. pylori and both ulcer 
disease and cancer, the presence in one patient group (87 or 97) of more diseased subjects may have biased the data. 4. How were the 62H. pylori IgG positive subjects used for examination of the antigenic profile of H. 
pylori chosen? Randomly? Otherwise? 
5. What were the main immunogenic proteins present in the ELISA antigen? And what biochemical procedure was used to enrich these? 6. Was the sensitivity and specificity of the ELISA calculated on the patient groups examined in this 
study or a previous study? Details should be given or a reference. 
7. What are the antigens represented on the Immunoblot Helicobacter pylori IgG? 
8. What is the sensitivity and specificity of this Imunoblotting kit? 
Results 
1. In the text section on "the prevalence of antibodies in O-87 and O-97 groups of patients" too much 
information is provided on the prevalence of infection in different age groups. This information can be 
read in Table1 and visualised in Figure 1. 2. The requirement for tables 2 and 3 are questionable. 
3. On page 9, line 3 the authors state that "The pick of H. pylori seroprevalence differs by one decade" - 
This should read 'The peak of .... 
Discussion 
1. The authors state that provided the ELISA used had of 87% sensitivity and 94% specificity the results
reflect satisfactorily the H. pylori infection rate". Does this infer that they question the sensitivity and 
specificity of the ELISA? 2. The finding that no difference existed in the prevalence of H pylori in the patient group (97) as compared with that in the blood donor group (97) is very unusual. The majority of studies show a 
significantly higher prevalence of infection in symptomatic subjects as compared with asymptomatic 
blood donors. The authors should comment upon this. 3. Although a higher prevalence of H. pylori infection was found in the 87 patient group as compared 
with that in the 97 patient group it is possible that this difference may relate to confounding factors. 
Firstly differences in the socioeconomic status between the year groups (87 and 97) may have 
contributed to the higher prevalence in 1987 and secondly, differences in the prevalence of H. pylori related diseases in the two groups might also have contributed (see comments 1-3 Materials and Methods above). 
4. The argument made by the authors in relation to the cohort phenomenon on Page 10 is circuitous. 
As paired sera were not collected then no comment can be made regarding the acquisition or loss of H. 
pylori. The finding that a higher prevalence of infection is present in the 87 group may be suggestive of 
a cohort phenomenon however again this is not definitive. What is meant by "mainly support". 
5. The authors state on Page 11 that their data suggests that CagA and/or VacA status are not the only 
factors that influence gastric cancer rates. Although this is correct it is certainly not the first study to demonstrate this point. Indeed there are numerous papers in the literature over many years that demonstrate this point. The authors should refer to at least one or more of these. 
6. As stated above it is now quite clear that the development of gastric cancer is multifactorial and thus 
the final sentence of the manuscript is redundant. 
Competing interests:
None declared.
assistant