Reviewer's report
Title:Social disparities in the use of colonoscopy by primary care physicians in
Ontario
Version: 9Date:3 May 2011
Reviewer: Carl J Lombard
Reviewer's report:
Patient neighbourhood information.
The calculation of the neighbourhood-level variables for a PCP raises some
concern. The description of the percentage of patients who reside in the Q!
neighbourhood seems fine since this percentage pertains the number of PCP
eligible patients. For the other variables the infomration (ie percentage of
population age 20 years and older) from the neighbourhood is linked to the PCP
patient and then aggregated to define and average charateristic. This is done in a
crude fashion.
Example: Two patients linked to two neighourhoods: patient 1 linked to area with
80% (800/1000) older then 20 years and patient 2 linked to an area with 50%
(1500/3000) over the age of twenty. For your study you use the average of 80%
and 50% and get a value of 65%. Taking the size of the areas into account one
gets a value of 100*2300/4000=57.5%. Why was the crude aggregation
considered adequate?
Outcome model.
In the statistical analysis it is stated that discretionaty colonoscopies are
modelled but in the results and description linked to Table 4 this is not so.
Assummed the later to be the case given the comment on discretionary col. in
the limitations.
Statistical model Table 4
In the statistical analysis section it is stated that due to a high degree of
collinearity the following variables were excluded: age of PCP, rurla location of
PCP practice and proportion of visible minorities. In the model we have the
ecological level variables % of lives(?) in rural location and % of non-immigrants.
It seems that the last variable is the proportion of visible minorities that was to be
excluded and that % if life in rural location has not been described earlier. The
description in the text and the final model should be clear to eliminate any
confusion of what is in and what is out.
It is stated that interactions was considered with time in the final model but these
results are not presented. The time effect which is the main factor for the paper
should also be presented as well as the time dependent associations. Will be a
bit of a challenge to do this in a nice way.
Table 3
This information should also be converted into graphs
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
declare that I have no competing interests'
Reviewer's report
Title:Social disparities in the use of colonoscopy by primary care physicians in
Ontario
Version: 9Date:3 May 2011
Reviewer: Carl J Lombard
Reviewer's report:
Patient neighbourhood information.
The calculation of the neighbourhood-level variables for a PCP raises some
concern. The description of the percentage of patients who reside in the Q!
neighbourhood seems fine since this percentage pertains the number of PCP
eligible patients. For the other variables the infomration (ie percentage of
population age 20 years and older) from the neighbourhood is linked to the PCP
patient and then aggregated to define and average charateristic. This is done in a
crude fashion.
Example: Two patients linked to two neighourhoods: patient 1 linked to area with
80% (800/1000) older then 20 years and patient 2 linked to an area with 50%
(1500/3000) over the age of twenty. For your study you use the average of 80%
and 50% and get a value of 65%. Taking the size of the areas into account one
gets a value of 100*2300/4000=57.5%. Why was the crude aggregation
considered adequate?
Outcome model.
In the statistical analysis it is stated that discretionaty colonoscopies are
modelled but in the results and description linked to Table 4 this is not so.
Assummed the later to be the case given the comment on discretionary col. in
the limitations.
Statistical model Table 4
In the statistical analysis section it is stated that due to a high degree of
collinearity the following variables were excluded: age of PCP, rurla location of
PCP practice and proportion of visible minorities. In the model we have the
ecological level variables % of lives(?) in rural location and % of non-immigrants.
It seems that the last variable is the proportion of visible minorities that was to be
excluded and that % if life in rural location has not been described earlier. The
description in the text and the final model should be clear to eliminate any
confusion of what is in and what is out.
It is stated that interactions was considered with time in the final model but these
results are not presented. The time effect which is the main factor for the paper
should also be presented as well as the time dependent associations. Will be a
bit of a challenge to do this in a nice way.
Table 3
This information should also be converted into graphs
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
declare that I have no competing interests'
Please review this paper.
user
Reviewer's report
Title:Social disparities in the use of colonoscopy by primary care physicians in
Ontario
Version: 9Date:3 May 2011
Reviewer: Carl J Lombard
Reviewer's report:
Patient neighbourhood information.
The calculation of the neighbourhood-level variables for a PCP raises some
concern. The description of the percentage of patients who reside in the Q!
neighbourhood seems fine since this percentage pertains the number of PCP
eligible patients. For the other variables the infomration (ie percentage of
population age 20 years and older) from the neighbourhood is linked to the PCP
patient and then aggregated to define and average charateristic. This is done in a
crude fashion.
Example: Two patients linked to two neighourhoods: patient 1 linked to area with
80% (800/1000) older then 20 years and patient 2 linked to an area with 50%
(1500/3000) over the age of twenty. For your study you use the average of 80%
and 50% and get a value of 65%. Taking the size of the areas into account one
gets a value of 100*2300/4000=57.5%. Why was the crude aggregation
considered adequate?
Outcome model.
In the statistical analysis it is stated that discretionaty colonoscopies are
modelled but in the results and description linked to Table 4 this is not so.
Assummed the later to be the case given the comment on discretionary col. in
the limitations.
Statistical model Table 4
In the statistical analysis section it is stated that due to a high degree of
collinearity the following variables were excluded: age of PCP, rurla location of
PCP practice and proportion of visible minorities. In the model we have the
ecological level variables % of lives(?) in rural location and % of non-immigrants.
It seems that the last variable is the proportion of visible minorities that was to be
excluded and that % if life in rural location has not been described earlier. The
description in the text and the final model should be clear to eliminate any
confusion of what is in and what is out.
It is stated that interactions was considered with time in the final model but these
results are not presented. The time effect which is the main factor for the paper
should also be presented as well as the time dependent associations. Will be a
bit of a challenge to do this in a nice way.
Table 3
This information should also be converted into graphs
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
declare that I have no competing interests'
assistant