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Peer review report 5 on “A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials.”
International Journal of Surgery 13 Supplement 1 (2015) S66
Contents lists available at ScienceDirect
International Journal of Surgery journal homepage: www.journal-surgery.net
Peer review report
Peer review report 5 on “A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials.” 1. Original submission 1.1. Recommendation Major Revision.
1.2. Comments to the author I have mixed feelings about this paper. On the one hand, the topic is important and a systematic review is justified. On the other hand, there are a number of shortcomings in the paper as it stands. 1 The introduction and literature review is very long winded and could be made considerably crisper. The major point that the authors seem to be making is that a) incisional hernia is an important clinical problem and b) the Cochrane review of 2011 does not conclusively settle the question of the comparison between laparoscopic and open repair. This does, however, get slightly lost in a detailed discussion of previous papers which does not contribute to the main argument. 2. The description of the methodology adopted is imprecise. The authors write about “standardised methods” and “standardised criteria” but it is difficult to work out exactly what the standardisation was. Although there is a paragraph setting out what the authors mean by a “quality study” it is difficult to follow. A table setting out the criteria used in their judgements would be helpful. The PRISMA flowchart is completely meaningless. At each exclusion stage it should give the reasons for the exclusion. As it stands it does not explain any of the decisions taken so the reader is unable to judge the worth of the study. 3. There is considerable repetition between sections e for example, we are told several times that some data were excluded because of heterogenity. Again, this makes the paper unnecessarily wordy. 4. I got lost in the description of the analysis. The authors state that they looked at 4 variables e 2 continuous and 2 binary (it would have been helpful to specify them at this point rather than leave the reader to decide what they were through subsequent reading). They then state that they expressed the continuous variables using mean and standard deviations and the noncontinuous using medians and interquartile ranges. Binary data is categorical and cannot be expressed in terms of median. DOI of published article: http://dx.doi.org/10.1016/j.ijsu.2015.05.050. http://dx.doi.org/10.1016/j.ijsu.2015.06.038 1743-9191
The decision to use non-parametric statistical tests is usually based on non-normality of data, not on whether it is continuous or not. They state that they analysed the continuous variables using Student's t test and the non-continuous using Mann Whitney U. Again, Mann Whitney U is inappropriate for categorical data which should be analysed using chi-square. 5. The detailed explanation of how to interpret a Forest plot is unnecessary. It is now widely used and understood. 6. The inclusion of a study with only 8 weeks follow up in the estimate of recurrence is unacceptable. That study could have been excluded from this particular calculation and the metaanalysis based on the remaining studies. It has been known for 30 years that incisional hernia may occur up to 7 years after the initial surgery (KG Harding, M Mudge, SJ Leinster, and LE Hughes Late development of incisional hernia: an unrecognised problem. Br Med J (Clin Res Ed).1983 286(6364):519e520). A defect present at 8 weeks would suggest a failure of primary repair rather than a recurrence. The authors do draw attention to this problem in the discussion but it still does not exempt them from the criticism of having included it. 7. The quality of the English is erratic. Careful editing is needed. 2. First revision 2.1. Recommendation Accept.
2.2. Comments to the author This is much improved. The difference between this study and the previous Cochrane review are now obvious. The results are clearly set out and the discussion is helpful. The conclusions are in keeping with the data presented. Sam Leinster, BSc MD FRCS SFHEA, Emeritus Professor of Medical Education University of East Anglia, Norwich Medical School, Vassars, Common Road, East Tuddenham, Dereham, Norfolk NR20 3AH, United Kingdom E-mail address: [email protected]. Available online xxx
Contents lists available at ScienceDirect
International Journal of Surgery journal homepage: www.journal-surgery.net
Peer review report
Peer review report 5 on “A systematic review of laparoscopic versus open abdominal incisional hernia repair, with meta-analysis of randomized controlled trials.” 1. Original submission 1.1. Recommendation Major Revision.
1.2. Comments to the author I have mixed feelings about this paper. On the one hand, the topic is important and a systematic review is justified. On the other hand, there are a number of shortcomings in the paper as it stands. 1 The introduction and literature review is very long winded and could be made considerably crisper. The major point that the authors seem to be making is that a) incisional hernia is an important clinical problem and b) the Cochrane review of 2011 does not conclusively settle the question of the comparison between laparoscopic and open repair. This does, however, get slightly lost in a detailed discussion of previous papers which does not contribute to the main argument. 2. The description of the methodology adopted is imprecise. The authors write about “standardised methods” and “standardised criteria” but it is difficult to work out exactly what the standardisation was. Although there is a paragraph setting out what the authors mean by a “quality study” it is difficult to follow. A table setting out the criteria used in their judgements would be helpful. The PRISMA flowchart is completely meaningless. At each exclusion stage it should give the reasons for the exclusion. As it stands it does not explain any of the decisions taken so the reader is unable to judge the worth of the study. 3. There is considerable repetition between sections e for example, we are told several times that some data were excluded because of heterogenity. Again, this makes the paper unnecessarily wordy. 4. I got lost in the description of the analysis. The authors state that they looked at 4 variables e 2 continuous and 2 binary (it would have been helpful to specify them at this point rather than leave the reader to decide what they were through subsequent reading). They then state that they expressed the continuous variables using mean and standard deviations and the noncontinuous using medians and interquartile ranges. Binary data is categorical and cannot be expressed in terms of median. DOI of published article: http://dx.doi.org/10.1016/j.ijsu.2015.05.050. http://dx.doi.org/10.1016/j.ijsu.2015.06.038 1743-9191
The decision to use non-parametric statistical tests is usually based on non-normality of data, not on whether it is continuous or not. They state that they analysed the continuous variables using Student's t test and the non-continuous using Mann Whitney U. Again, Mann Whitney U is inappropriate for categorical data which should be analysed using chi-square. 5. The detailed explanation of how to interpret a Forest plot is unnecessary. It is now widely used and understood. 6. The inclusion of a study with only 8 weeks follow up in the estimate of recurrence is unacceptable. That study could have been excluded from this particular calculation and the metaanalysis based on the remaining studies. It has been known for 30 years that incisional hernia may occur up to 7 years after the initial surgery (KG Harding, M Mudge, SJ Leinster, and LE Hughes Late development of incisional hernia: an unrecognised problem. Br Med J (Clin Res Ed).1983 286(6364):519e520). A defect present at 8 weeks would suggest a failure of primary repair rather than a recurrence. The authors do draw attention to this problem in the discussion but it still does not exempt them from the criticism of having included it. 7. The quality of the English is erratic. Careful editing is needed. 2. First revision 2.1. Recommendation Accept.
2.2. Comments to the author This is much improved. The difference between this study and the previous Cochrane review are now obvious. The results are clearly set out and the discussion is helpful. The conclusions are in keeping with the data presented. Sam Leinster, BSc MD FRCS SFHEA, Emeritus Professor of Medical Education University of East Anglia, Norwich Medical School, Vassars, Common Road, East Tuddenham, Dereham, Norfolk NR20 3AH, United Kingdom E-mail address: [email protected]. Available online xxx