September 6, 2011
BMC Health Services Research
RE: MS: 5408010505264236, entitled, Implementation of ICD-10 in Canada: How has it
affected coded hospital discharge data?
Dear Prof. Paul Brown,
Thank you for giving us the opportunity to resubmit the above manuscript. The manuscript has
been revised in response to the reviewer’s minor comments that you provided us. Below, we
provide an itemized summary of the changes made. Reviewers’ comments are shown in bold,
followed by our responses. Direct changes to the manuscript are done in tract changes in the
document.
Reviewer #1: Kerry Innes
1. Are the data sound?
Not qualified to say but I did feel that the data presented could have been presented in a
more easily digestible way and with clearer graphical representation of some of the major
findings, e.g. av no of diagnoses over the study period (2.58) is not obvious in the
tables/figures. Discretionary.
In Figure 2 we are trying to display the provincial trends in average diagnoses over time (98-05)
rather than focusing on the specific average number of diagnoses (i.e. 2.58). However, to make
the diagram clearer and remind the reader of the average number of diagnoses over the time
period we have added a line to the graphs representing the average for each diagnosis type, see
revised figures 2a-c.
2. Are the discussion and conclusions well balanced and adequately supported
by the data? The discussion and conclusions are quite brief - see point 8.
We have added more text to the discussion and conclusion.
3. Do the title and abstract accurately convey what has been found?
The title indicates that this study is looking at the effect on the data but concludes that the
implementation did not substantially change coding practice. While the data were
obviously analysed, there was not an in depth discussion of the affects of the change in
coding practice on the data - acknowledging that these changes were minimal, I think there
could have been more discussion about the possible causes of the practice changes and
perhaps some detailed examples of the data impact, minimal though they were.
Discretionary.
We have changed the title from: “Implementation of ICD-10 in Canada: How has it affected
coded hospital discharge data?” to “Implementation of ICD-10 in Canada: How has it impacted
coded hospital discharge data?”. We have included in the discussion the possible causes of the
practice changes and perhaps some detailed examples of the data impact on page 11 and 12.
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4. In addition, I think there is inadequate explanation of what the premise is for
using average number of coded diagnoses. What does it indicate? The conclusion that
coding practice was substantially unchanged, cannot reasonably be deduced only from an
analysis of av no of codes assigned. It is only one indicator of possible practice change.
Coding practice could be significantly different and produce the same number of codes.
Hence my comment about going more deeply into this issue. It is a useful thing to know
that there is no significant change in no of codes, but it would be far more interesting to
investigate the types of diseases the codes represent pre and post, particularly in
the provinces where the no of codes changed. Discretionary
Thank you, we agree that average diagnosis is only one indicator of possible practice change.
Thus we looked at the proportion of Charlson scores (which include 17 conditions) pre and post
ICD-10 implementation. We have now also included a table showing the distribution of
Charlson Scores by province (see Table 3). Thus the results give some reassurance that the
different types of disease coding pre and post are similar.
5. Is the writing acceptable? Yes but quite brief
We have added additional text to the manuscript in both the introduction and discussion.
6. Minor: in my copy there seem to be 2 representations of Figure 2(c)- last 2
pages.
We have removed the copy of Figure 2(c).
Reviewer #2 : Vijaya Sundararajan
1. A table describing the provinces being studied in the following manner:
• Population
• Number of hospitals
• Number of multiday discharges
• Year ICD-10-CA introduced
• Whether coded hospital morbidity data are used to develop funding models to
support prospective payment (DRG).
• Coder training – province wide or hospital specific/ standardised or locally
developed
• Presence of any regular auditing of coding
We have added an additional table (Table 1) and included year ICD-10-CA was introduced,
provincial population, number of hospitals/clinical units submitting data and number of
discharges per year. Unfortunately we were unable to provide coder training as it is regulated at a
provincial level and changes from year to year, region to region, and hospital to hospital.
Documentation of coder training is limited. Regular auditing of coding is done at a national
level by the Canadian Institute of Health Information. We have included this information in the
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discussion rather than this table. Also, we were unable to find information on all provinces
whether coded hospital morbidity data are used to develop funding models to support
prospective payment (DRG) thus as it was not inclusive of all provinces we did not include that
information.
2. Table 1: Presentation of the distribution of Charlson scores 1-year pre and
1-year post for each province would be helpful.
The reason we did not provide the distribution of Chalrson scores 1-year pre and post for each
province is due to the length of the table (9 provinces x 7 lines Charlson score = 63 rows).
Instead we have provided an additional table which provides the distribution of Charlson scores
(grouped as 0, 1-2 and 3+) 1 -year pre and post for each province (see Table 3).
3. Table 2: This is very interesting table and would improve with the presentation
of a time-series across the years of change.
4. Table 3: Also interesting. Would improve with the presentation of a time series
and by the further description of the 4 patient volume levels with the range of
hospital count (i.e: what is the range in the number of hospital discharges for the
low level?)
We could provide time-series tables, however each province initiated ICD-10 at a different year.
Thus the reason we just presented pre and post for simplicity and for readers to easily digest the
information. If the reviewer still thinks it is important we will try to add in the time series (but
will first need to obtain data approval first from Statistics Canada). Further, at this time we are
waiting for approval to re-obtain data from Statistics Canada to further describe the 4 patient
volume levels. Once we have this information available to us we are happy to add it into the
Table.
5. Finally, I wonder whether it would be possible to conduct further statistical
analysis in order to assess whether the coding completeness was significantly
different after the introduction of ICD-10-CA in particular provinces and in
particular hospitals with specific characteristics (low volume, non-teaching,
rural)?
It would be ideal to look at coding completeness; however we are unable to look at this without
chart re-abstraction. Thus unfortunately we are unable to assess coding completeness. This will
be part of a future study.
6. Assessment of any relationship of changes to coding completeness to
particular characteristics of the province, such as whether the coded data are
used to develop funding models, quality of code training and whether the
province has a program to audit the coded data.
Same comment as #5 above.
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7. Analysis, p8, last line: why was mean used rather than median?
In terms of number of diagnoses, we did assess the median however the trends were very similar
to the mean. Thus we provided the mean. We can however provide the median and mean if the
reviewers deem it essential.
8. Background, p4, lines20-22, and p5, lines 1-3: The validation studies
presented appear to be for cause of death coding in death certificates. These
results may not have any bearing for hospital morbidity coding as the process
from the bedside to database for mortality versus morbidity coding differ.
Excellent point, we have deleted this sentence (and the references to the validation studies of
death certificate coding) in the background section and instead inserted a study by Quan et al.
9. Analysis, p7, bottom: rather than ‘ the prevalence of a least one of the
seventeen Charlson …’ how about ‘the proportion of records with at least on
comorbidity’?
Thank you, we have made this change.
10. Discussion, p13, end of last paragraph: average number of diagnostic codes
per hospital visit may be related to overall patient complexity, but not necessarily
to the severity of disease.
We have clarified this in the limitations section and removed the sentence relating average
number of diagnostic codes per hospital to severity of disease.
Minor Essential Revisions
1. Background, p4, line 12: rather than ‘purposes other than administrative data
analysis’ would ‘purposes other than their primary use in funding and
administration’ be clearer?
The suggestion made is clearer and we have changed it in the background section (p4) to:
“However, the use of these data for research purposes (i.e.purposes other than their primary use
in funding and administration) is based on the assumption that they provide valid information
about diagnoses, comorbidity and clinical services.”
2. Background, p4, line 19: non-specific in ‘non-specific conditions’ not needed
We have removed non-specific.
3. Background, p5, line 5: add ‘for hospital morbidity coding’ at end of sentence
at beginning of line.
We have added this to the end of the sentence.
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4. Background, p5, end of line 11, beg of 12: No intent in the staggered
introduction of ICD-10, so it is not an ‘approach’. Perhaps better to say simply
‘The staggered introduction…’.
We have made the suggested change.
5. Analysis and beyond: The abbreviation of provincial names makes the
manuscript a bit more difficult to understand.
The reason we chose to abbreviate the name of the provinces is because they are too long to
write out in full in the figures and tables (such as PEI=Prince Edward Island). We ordered the
abbreviations to group different regions (i.e. Eastern Canada, Western Canada). If the reviewer
still feels this is an important issue we could 1) delete the abbreviations in the text and only use
them in the figures/tables, 2) add an additional figure - a map of Canada with the abbreviations
of the provinces to help clarify or 3) remove all abbreviations from the paper (as previously
stated this would be more challenging to do in the figures/tables).
6. Figure 2c has been shown twice
The additional copy has been removed.
Other Comments: The background section of abstract needs more details.
Thank you, we have included more details in the background section.
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