Reviewer ’s report  
 
Title: Predictors of cervical cancer screening service utilization among commercial sex workers 
in North West Ethiopia: A case -control study.  
 
Version: 0 Date: 06 Mar 2019  
 
Reviewer: Paolo Giorgi Rossi  
 
Reviewer's report:  
 
The paper present an original and interesting study about the predictors of screening uptake 
among sex workers in Nor th West Ethiopia. The study is well designed and the analyses are well 
conducted. Reporting can be improved, particularly for the quality of English; unfortunately I am 
not a native English speaker so I cannot help too much in this.  
 
 
Specific comments  
 
Abstract 
 
The background is too long. I suggest starting directly from the situation in Ethiopia (5th line).  
 
Results: CCSU and AOR should be explained.  
 
Please firstly report the descriptive results: how many women have been screened.  
 
Conclusion: I suggest sayi ng that "screening utilization is higher in ..." not "high" because the 
absolute level of coverage is low in all groups.  
 
 
Background  
 
In general this chapter can be shortened.  
 
First page, 5th line: change "new arrivals" in "new cases" or "incident cases"  
 
First page second paragraph: merge this paragraph with the first one and avoid repeating the 
same concepts: incidence and mortality.  
 
Third page, first paragraph: please report briefly the most important the results of the two 
referenced studies.  
 
Third page , second par, third line: please change "determinants of the screening program where" 
in "determinants of screening uptake in".  
 
Methods  
 
Please describe how women were conducted and recruited. Where did the interviews occur? Was 
the contact opportunistic o r were the women contacted in some way?  
 
The selection of variables to be included in the multivariate models sould be done in the light of 
the possible underlying causal network.  
 
Age categories are not well balanced.  
 
 
Results  
 
Tables: the column "differenc e" is not clear reported in this way.  
 
What is "multiple sexual practices"?  
 
Please explain better what is the "frequency of facility visit/year"? Do you mean more or less 6 
visits per year? Could you describe better the distribution of the women according t o the number 
of visit/year?  
 
What is the "virginal discharge"?  
 
Please note that all the variables with the strongest association are on the same causal chain: 
provider's recommendation, vaginal examination, history of STI, are all the consequence or the 
cause of the frequency of visits. Adjusting for each other is not a good idea.  
 
 
Discussion  
 
Please discuss the possible causal chain: STI -&gt; frequency of visit -&gt; (probability of 
receiving recommendation AND vaginal visit) -&gt; Pap test. Adjusting for recommendation and 
vaginal visit at the same time is not a good idea.  
 
second page, first paragraph: the lack of association between knowledge/awareness could be 
explained in this population: in fact, awareness is necessary to increase the probability of a 
contact between women and health service when she is well, in your population, women have all 
already a constant contact with the service, so the eventual effect of knowledge, if it exists in the 
general population at all, here it is irrelevant.  
 
Third page , first paragraph: this part about health extension workers is not really linked to your 
results. I suggest dropping it.  
 
Third page, second paragraph, first line: cervical cancer is not the most common infectious 
disease; I would say it is a relatively rar e consequence of the most common sexually transmitted 
infection, i.e. HPV.  
Last page, last par: this interpretation is interesting, but firstly check what happens if you adjust 
for other variables, but recommendation, STI and frequency of visit.  
    
 
Limi tations  
 
I do not agree that a Case Control study cannot prove causality in any case. It depends on the 
opportunity you have to control for possible confounders and how much biases are strong in the 
study. The main limit is the lack of a clear pattern of ca uses that could be tested.  
 
 
Conclusions  
 
I would start the conclusion with the proportion of women who are covered with Pap test, then 
the predictors.     
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls  are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please speci fy what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Not suitable for publication unless extensively edited  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1.  Have you in the past five years r eceived reimbursements, f ees, funding, or salary 
from an organisation that may in any way gain or lose financial ly from the 
publication of this manuscript, either now or in the future?  
 
2.  Do you hold any stocks or shares in an organisation that may in any way gain or 
lose financially from the publication of this manuscript, either now or in the 
future?  
 
3.  Do you hold or are you currently applying for any patents  relating to the content 
of the manuscript?  
 
4.  Have you received reimbursements, fees, funding, or salary from an organization 
that holds or has applied for patents relating to the content of the manuscript?  
 
5.  Do you have any other financial competing interests?  
 
6.  Do you have any non -financial com peting interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have  no competing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests  
 
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