Copyright
by
David B. Trant, M.D.
2010
The Capstone Committee for David B. Trant, MD Certifies that this is the approved
version of the following capstone:
Undetermined Natural Causes: Do Physicians Code for Uncertainty In
Cause of Death?
Committee:
Susan C. Weller, PhD, Supervisor
Christine M. Arcari, PhD, MPH
Karl Eshbach, PhD
__________________
Dean, Graduate School
Undetermined Natural Causes: Do Physicians Code for Uncertainty In
Cause of Death?
by
David B. Trant, M.D.
Capstone
Presented to the Faculty of the Graduate School of
The University of Texas Medical Branch
in Partial Fulfillment
of the Requirements
for the Degree of
Master of Public Health
The University of Texas Medical Branch
August, 2010
Undetermined Natural Causes: Do Physicians Code for Uncertainty In
Cause of Death?
Publication No._____________
David B. Trant, MD, MPH
The University of Texas Medical Branch, 2010
Supervisor: Susan C. Weller
Abstract
Cause of death (COD) determination by physicians on the death certificate can be
difficult when the conditions leading to death are unclear or uncertain. The Center for
Disease Control (CDC) recommends the classification for these deaths should be
“undetermined natural causes” (ICD-10 code R99). Physicians may incorrectly code
COD in patients who die of undetermined natural causes, instead listing heart disease
(ICD-10 I00-I09, I11, I13, I20-I51)), or another COD, on the death certificate. This may
have important implications in the calculation of mortality statistics, particularly when
using the Mortality Medical Data System (MMDS), a system to automate the entry,
classification, and retrieval of cause-of-death information reported on death certificates.
Forty-two primary care physicians participated in a randomized, controlled trial assessing
completion of the death certificate for a patient dying of undetermined natural causes.
The physicians were randomized into two groups: the first group reported the COD using
an open-ended format, and the second group selected COD from a list of potential
choices (including “undetermined natural causes”) for the death certificate COD fields.
The study has two aims. The first aim is to determine the percentage of physicians that
correctly code the death certificate, and to see if responses are sensitive to having “nonspecific” COD as a possible response. The second aim is to assess the reliability of
coding COD by comparing physician reported COD to the MMDS transformations of
those reports.
v
Overall, 62.5% of respondents chose an underlying COD that was categorized as
“symptoms, signs and abnormal clinical and laboratory findings, not elsewhere
classified,” (ICD-10 codes R00-R99), and the remaining 37.5% reported a specific COD,
such as heart disease (I00-I09, I11, I13, I20-I51). There was no statistical difference [χ2
(1, N = 40) = 1.932, p = 0.165] in the frequency of nonspecific R codes used by the
respondents for the underlying COD completing either the open-ended format (52%
nonspecific, 48% specific) compared to the close-ended format (74% nonspecific, 26%
specific).
Processing with the Mortality Medical Data System (MMDS) resulted in an underlying
COD category of 27.5% non-specific R codes and 72.5% specific causes (60% were the
heart disease category), nearly opposite the numbers for the original physician-reported
underlying COD. The MMDS-generated COD did not show a statistically significant
difference [χ2 (1, N = 40) = 2.489, p = 0.115] for frequency of R code generation
between the open-ended format (38% nonspecific, 62% specific) and the close-ended
format (16% nonspecific, 84% specific) .
This study suggests that while the majority of physicians may correctly code for an
underlying COD using codes R00-R99 for a person dying of undetermined natural
causes, software used for national statistical reporting may be biased to report the
underlying COD category as heart disease (I00-I09, I11, I13, I20-I51).
vi
Table of Contents
List of Tables ....................................................................................................... viii
List of Figures ........................................................................................................ ix
BACKGROUND .....................................................................................................1
METHODS ..............................................................................................................8
RESULTS ..............................................................................................................14
DISCUSSION ........................................................................................................19
BIBLIOGRAPHY ..................................................................................................23
APPENDIX ............................................................................................................25
vii
List of Tables
Table 1. Table of possible sequences for the death certificate for the sample case with
corresponding ICD-10 codes. ........................................................................................... 11
Table 2. Survey responders’ characteristics and use of R code for underlying COD ..... 14
Table 3. Physician-determined and software-generated underlying cause of death
categories for each survey group based on the WHO ICD-10 classification. .................. 16
Table 4. Physician-Determined Underlying COD. X 2 (1, N = 40) = 1.932, p = 0.165 ... 17
Table 5. Software-generated underlying COD. X 2 (1, N = 40) = 2.489, p = 0.115......... 17
Table 6. Software-generated underlying COD specificity versus that determined by the
physician. .......................................................................................................................... 18
Table 7. Comparison of heart disease diagnosis as the underlying COD category. ........ 18
viii
List of Figures
Fig. 1. U.S. Standard Certificate of Death (rev. 11/2003) ................................................. 2
Fig. 2. Case History No. 12 from Physician Handbook on Medical Certification of Death
(Department of Health and Human Services, CDC, 2003). ................................................ 9
Fig. 3. U.S. Standard Certificate of Death (rev. 11/2003) excerpt. ................................. 10
Fig. 4. Single cause of death without other significant conditions. ................................. 20
Fig. 5. Cause of death with significant contributing condition in Part II......................... 21
ix
BACKGROUND
Physicians are often presented with the difficult task of determining cause of death
(COD) when completing a death certificate which is then used to calculate national
mortality statistics. Mortality statistics can be used to systematically assess and monitor
the health status of populations and are useful in formulating policies to prevent or reduce
mortality and improve quality of life. Unfortunately, physician errors in determining and
coding COD and possible bias for listing specific causes over nonspecific or uncertain
conditions may lead to inaccuracy of mortality statistics. This study explores physician
coding of COD when faced with a case in which the patient dies of uncertain or
nonspecific causes.
The U. S. Standard Certificate of Death (Fig. 1) provides spaces for the certifying
physician, coroner, or medical examiner to record pertinent information concerning the
diseases or conditions that either resulted in (Part I) or contributed to (Part II) death. The
medical certification portion of the death certificate expresses “the opinion of the certifier
as to the relationship and relative significance of the causes which he reports.” (National
Center for Health Statistics, 2010)
A cause of death is the morbid condition or disease leading directly or indirectly to death.
The underlying cause of death is the disease or injury which initiated the events leading
directly or indirectly to death, and this physician-determined underlying cause of death is
1
Part I
Part II
Fig. 1. U.S. Standard Certificate of Death (rev. 11/2003)
2
the last condition listed in Part I of the death certificate. Other significant condition(s)
which contributed to death but were not related to the immediate cause of death is (are)
entered in Part II of the death certificate. (National Center for Health Statistics, 2010).
Computer automation has greatly simplified the collection of mortality data and coding of
the death certificate data using the ICD coding rules. Data collected from death
certificates by government agencies is processed by the Mortality Medical Data System
(MMDS) software. (CDC/ National Center for Health Statistics, 2010) This software is
composed of four basic programs, SuperMICAR, MICAR200, ACME, and TRANSAX.
These programs automate the entry, classification, and retrieval of cause-of-death
information reported on death certificates and the software is used by state and federal
agencies for statistical reporting of mortality data. SuperMICAR is designed to
automatically encode cause-of-death data into numeric entity reference numbers. The
output from this program serves as input for the MICAR200, which automates the
multiple cause coding rules and assigns diagnosis codes described in the ICD to each
numeric entity reference number. The ACME portion of this software applies the World
Health Organization (WHO) rules to the ICD codes generated by MICAR200 and selects
an underlying cause of death. The final program, TRANSAX, converts the ACME
output data into fixed format and translates the data into a more desirable statistical form
using the linkage provisions of the ICD, and is used for preparing files for transmission to
the National Center for Health Statistics (NCHS) to provide statistical information that
will guide actions and policies to improve the health of the US population.
3
Beginning in January 1999, the United States began using the International Classification
of Diseases, Tenth Revision (ICD-10) to classify causes of death reported on death
certificates. ICD-10 is “designed to promote international comparability in the
collection, processing, classification, and presentation of mortality statistics, including
providing a format for reporting causes of death on the death certificate.” (CDC/ National
Center for Health Statistics, 2009a) The reported conditions are translated into medical
codes through the use of coding rules contained in the ICD. These rules allow for
systematic selection of a single cause of death from the reported sequence of conditions
on the death certificate.
Using the ICD-10 rules, the underlying cause of death may actually be different than that
determined by the physician on the death certificate. For example, Rule A specifies that
when an ill-defined cause of death such as senility is listed on the death certificate along
with a more specific diagnosis or diagnoses, the cause of death should be re-coded as if
the ill-defined condition had not been reported. If the physician were to code the death
certificate as “acute myocardial infarction” (coded as Acute Ischemic Heart Disease,
Unspecified - I24.9) due to “advanced age” (coded as Senility - R54), then the physiciandetermined underlying cause of death per the death certificate instructions would be the
last item listed in Part I; in this instance, Senility – R54. However, by application of
ICD-10 Rule A, the underlying COD becomes Acute Ischemic Heart Disease,
Unspecified - I24.9.
4
ICD-10 describes multiple diagnoses grouped into various categories roughly based on
organ systems. This system works well when the cause of death is clear, and specific
diagnoses can be found among these many categories. However, not all deaths have
obvious specific causes; in such instances ICD-10 codes R00-R99 (Symptoms, signs and
abnormal clinical and laboratory findings, not elsewhere classified) might be used to code
a number of unclear, nonspecific or uncertain causes of mortality, such as R54 (senility),
R98 (unattended death), and R99 (other ill-defined and unspecified causes of mortality).
The plethora of possible diagnoses and their various combinations on the death certificate
allow for great latitude by the physician in coding the cause of death. The innumerable
potential combinations may lead to different coding of the cause of death for the same
case by two different physicians. (Brown, et al., 2007) This variation in coding can have
a negative impact when the ICD-10 coding rules are applied, potentially resulting in two
very different reported diagnoses for the underlying cause of death.
Some researchers have shown COD error rates ranging from 16% to 50%, which
questions the validity of information from the cause-of-death registry for scientific or
administrative purposes. Lakireddy et. al. (Lakkireddy, Gowda, Murray, Basarakodu, &
& Vacek, 2004) showed that 45% of medical residents incorrectly identified a
cardiovascular event as the primary cause of death using a sample case of in-hospital
death due to urosepsis. Tavora et. al. (Tavora, Crowder, Kutys, & Burke, 2008) found
5
that in a series of autopsies on sudden deaths outside the hospital that the diagnosis of
coronary artery disease on the initial death certificate rendered before autopsy was
accurate only 50% of the time. James and Bull (James & Bull, 1996) described available
malignancy histological diagnoses being recorded on only 23.6% of death certificates, as
well as numerous other errors. In a literature review by Maudsley and Williams,
(Maudsley & Williams, 1996) they noted that deriving a useful estimate of death
certificate inaccuracies over multiple studies is difficult due to many inter-study
differences in definition of error (i.e. undefined ‘major clinical cause’ when compared
with autopsy, poorly defined clinicopathological correlation, variation in diagnostic
coding) as well as the measurement of the error (autopsy, chart review). These death
certificate errors may occur due to differences in medical opinion, training, knowledge of
medicine, available medical history, symptoms, diagnostic tests, and available autopsy
results. Even if extensive information is available to the certifier, causes of death may
still be difficult to determine.
Physicians may not be aware that it is acceptable to list a nonspecific or uncertain cause
of death on the death certificate, although the Centers for Disease Control and
Prevention, National Center for Health Statistics (CDC/NCHS) has specifically addressed
this problem:
If the certifier cannot determine a descriptive sequence of causes of death
despite carefully considering all information available and circumstances
of death did not warrant investigation by the medical examiner or
6
coroner, death may be reported as “unspecified natural causes."
(CDC/National Center for Health Statistics, 1997)
Interestingly, the NCHS seems to suggest that choosing an unspecified COD suggests
poor quality on the part of the physician certifier:
One index of the quality of reporting causes of death is the proportion of
death certificates coded to Chapter XVIII—Symptoms, signs and
abnormal clinical and laboratory findings, not elsewhere classified
(ICD–10 codes R00–R99). Although deaths occur for which underlying
causes are impossible to determine, the proportion coded to R00–R99
indicates the consideration given to the cause-of-death statement by the
medical certifier (CDC/National Center for Health Statistics, 2009).
So on the one hand, the physician is encouraged to code for uncertainty where
appropriate by the CDC/NCHS, but it is also suggested that such coding may not reflect
adequate consideration by the physician. This obviously gives a mixed message to
physicians considering using an unspecified COD, potentially biasing the physician to
produce a more specific and potentially incorrect COD.
Because physician reporting may be biased toward listing a specific disease or diseases
rather than nonspecific or unknown causes when uncertain about the actual cause of
death, this study tested for reporting differences between reports made when
7
“undetermined natural causes” is specifically a choice for cause of death and when it is
not. This study also explores the differences between what a physician reports as the
underlying COD on the death certificate, and what is reported for national vital statistics
after coding the physician’s responses with the MMDS software. The study has two
aims. The first aim is to determine the percentage of physicians that correctly code the
death certificate, and to see if responses are sensitive to having “non-specific” COD as a
possible response. The second aim is to assess the reliability of coding COD by
comparing physician reported COD to the MMDS transformations of those reports.
METHODS
A randomized controlled trial was used to compare responses of physicians in two
groups: one group reported the cause of death for a standardized case published by the
CDC (Department of Health and Human Services, CDC, 2003) in an open-ended format,
and the other group was asked to code the cause of death for the same standardized case
by selecting from a list of ten potential sequences for Parts I and II of the death certificate
COD. The protocol for this study was reviewed and declared exempt by the University
of Texas Medical Branch Institutional Review Board prior to beginning data collection.
SUBJECTS
The subjects were physicians who identified their primary specialty as Family Practice or
Internal Medicine and had primary practice locations in Baytown, Texas and the
8
surrounding communities of Highlands and La Porte, Texas. These subjects were
identified from reviews of local phone books, internet listings, county medical society
member rosters, information from local persons, and personal knowledge of the primary
investigator.
MEASURES
Subjects were randomized into two groups to receive one of the two survey versions.
Both versions contained a death case history (Fig. 2) from an example case: Case History
A 92-year-old male was found dead in bed. He had no significant medical history.
Autopsy disclosed minimal coronary disease and generalized atrophic changes
commonly associated with aging. No specific cause of death was identified. Toxicology
was negative.
Fig. 2. Case History No. 12 from Physician Handbook on Medical Certification of Death (Department of Health and
Human Services, CDC, 2003).
No. 12 from the CDC’s Physician Handbook on Medical Certification of Death
(Department of Health and Human Services, CDC, 2003). Version A included an excerpt
from the U.S. Standard Certificate of Death (rev. 11/2003) in which the physician was
asked to complete the cause of death section, item 32, Part I and II on this form for this
example case (see Fig. 3). Version B had a list of potential sequences of causes of death
that might be used on a death certificate for the example case, including the single listing
of “undetermined natural causes” (see Table 1).
The physicians who received this version were asked to choose the most appropriate
9
sequence applicable for this case. According to the CDC handbook, “undetermined
natural causes” listed alone in Part I is the correct coding of cause of death for this case.
Both versions of the survey (A and B) asked questions regarding specialty (Family
Practice, Internal Medicine, other), years since medical school completion, prior formal
training in death certificate completion (yes/no), how comfortable the physician was with
completing a death certificate (scale), and whether the physician had completed training
in their current primary specialty (yes/no). Additionally, the subjects were given a list of
conditions/diagnoses leading to death (including the nonspecific conditions of
Fig. 3. U.S. Standard
Certificate
of Death
11/2003) age)
excerpt.
undetermined
natural
causes
and(rev.
advanced
and asked: “For the following diseases
or conditions, please answer yes or no as to whether (in your opinion) this condition
would ever be acceptable as a single cause of death on the death certificate, without
listing any additional causes or conditions.”
10
Item 32, Part I
Scenario
#
a.
b.
1
Acute cerebrovascular
accident (I64)
2
Cardiac arrhythmia
(I49.9)
Atherosclerotic
coronary
artery disease
(I25.1)
3
Cardiac arrest (I46.9)
Undetermined
natural causes
(R99)
4
Undetermined natural
causes (R99)
5
Respiratory arrest
(R09.2)
6
Undetermined natural
causes (R99)
7
Acute myocardial
infarction (I21.9)
Atherosclerotic
coronary
artery disease
(25.1)
8
Ruptured cerebral
aneurysm (I60.90)
Atherosclerosis
(I70.9)
9
Advanced age (R54)
10
Cardiac arrhythmia
(I49.9)
c.
d.
Part II
Advanced age (R54)
Congestive
heart failure
(I50.2)
Atherosclerotic
coronary artery
disease (I25.1)
Coronary artery
disease (I25.1)
Acute
myocardial
infarction
(I21.9)
Heart failure
(I50.9)
Atherosclerotic
coronary artery
disease (I25.1)
Table 1. Table of possible sequences for the death certificate for the sample case with corresponding ICD-10 codes.
ANALYSIS
To determine if physicians incorrectly code COD in patients who die of undetermined
natural causes, the percentage of survey respondents who correctly used an R code (R0011
R99) was calculated. The two survey versions (open-ended responses vs specific
choices) were compared to determine differences by survey format using a chi square
test. Responses were categorized into 17 possible categories (15 leading causes of death,
all other causes of death, and R00-R99) and further collapsed into two categories:
Nonspecific (R codes) and Specific (other than R codes).
Coding of the text of the conditions/diagnoses listed by the physician into ICD-10 codes
was performed using the MMDS (CDC/ National Center for Health Statistics, 2010)
software. For both survey versions (A and B), the responses for the COD were entered
and processed with the SuperMICAR and MICAR200 programs, which are the first two
programs in the MMDS software. The output of these two programs is the ICD codes for
each of the conditions/diagnoses entered in Parts I and II on the COD. All coding done in
this manner by the software was individually reviewed by the author, and no
discrepancies were noted between what the physician entered and the descriptions of the
ICD diagnosis codes generated by the software.
For both survey versions, the last condition or diagnosis (the first if only one is listed)
chosen by the physician for item 32, part I was recorded as a new variable, the physiciandetermined underlying COD. This physician-determined underlying COD is in keeping
with the death certificate instruction directing the physician to “Enter the UNDERLYING
CAUSE (disease or injury that initiated the underlying events resulting in death) LAST.”
12
Survey responses for the completion of the death certificate were processed using the
MMDS software to generate the software-generated underlying COD.
Underlying COD (both physician-determined and software-generated) were grouped into
broad categories based on the WHO ICD-10 classification (see Table 1). These
categories are based on the 15 leading causes of death for the total population of the US
in 2006 (Heron, Hoyert, Murphy, Xu, Kochanek, & Tejada-Vera, 2009) with the
additional categories of deaths coded to Chapter XVIII of the ICD-10—Symptoms, signs
and abnormal clinical and laboratory findings, not elsewhere classified (ICD–10 codes
R00–R99), plus a category for any residual.
Statistical analyses were performed with SAS version 9.2 statistical software. (SAS
Institute, 2010) Descriptive characteristics (specialty, prior death certificate training,
resident/intern status, years since medical school graduation) were reported. Because it
was thought that specific physician characteristics might influence their selection of
undetermined natural causes as a single cause of death, these characteristics were also
compared to the use of choosing a non-speciifc cause. In order to test whether the format
of the question affected physician responses, the proportion of physician reportiong nonspecific causes was compared between those who received the open-ended format (A)
and those who received the coded-ended format (B). Then, odds ratios with confidence
intervals were also calculated to determine the likelihood of a COD reflecting
uncertainty, which was defined as a diagnosis coded to R00-R99.
13
Physician-determined and software-generated underlying cause of death categories for
each survey group based on the WHO ICD-10 classification were also compared.
Agreement between the orginal responses and those obtained from the coding software
were compared with a kappa coefficient.
RESULTS
Of the 70 physicians contacted, 42 participated, for a 60% response rate. Two surveys
Characteristic
Total
Survey Version
A
B
Specialty
FP
IM
Years Since Medical School Graduation
0-10
11-20
21-30
>30
Training Status
Intern/Resident
Not in training program
Prior Death Certificate Training
Yes
No
n (%)
n (%) of Physicians in Group Using a R
Code as Underlying COD
40 (100)
25 (62.5)
21 (52.5)
19 (47.5)
11 (52)
14 (74)
32 (80)
8 (20)
20 (62.5)
4 (50)
12
9
12
7
11 (92)
3 (33)
6 (50)
5 (71)
8 (20)
32 (80)
8 (100)
17 (53)
2 (5)
38 (95)
1 (50)
24 (63)
Table 2. Survey responders’ characteristics and use of R code for underlying COD
14
were incomplete, and were not included in the analysis. 80% identified their primary
specialty as Family Practice (FP), and the remainder were Internists (IM). 20 % were FP
residents from the local training program. Only 5% of all the responders reported having
received any death certificate completion training (only 9% of the Family Practitioners
and none of the Internists had prior death certificate training). Years since medical school
for all responders ranged from 2 to 61, with a mean of 19.4. Table 2 presents this data in
further detail. There were a nearly equal number of responses for each version of the
survey (A=21, B=19).
Table 3 shows the distribution of responses by ICD category for each group.
Of the 17 possible COD categories, the respondents utilized relatively few ICD
categories for the underlying cause of death in this study, which is not unexpected given
the paucity of signs and symptoms in the sample case. The data in table 3 was grouped
into two general categories for analysis based on whether they were coded to ICD-10 Rcodes: Nonspecific (R00-R99) and Specific (other than R00-R99). The overall
physician-determined and software-generated underlying COD were in agreement only
65% of the time (κ= .37).
Overall, 62.5% (25/40) of physicians reported the underlying COD correctly as
“Nonspecific” (see Table 4). However, fewer physicians coded for nonspecific causes in
the open-ended format (52%) than when they had a list of possible causes (74%).
15
ICD-10
Description
I00-I09,
Diseases of the heart
I11,I13,I20-I51
C00-C97
Malignant neoplasms
I60-I69
Cerebrovascular diseases
J40-J47
Chronic lower
respiratory diseases
Open format
(version A)
n (%)
Structured format
(version B)
n (%)
Physiciandetermined
Softwaregenerated
Physiciandetermined
Softwaregenerated
6 (29)
9 (43)
4 (21)
15 (79)
-
-
-
-
1 (5)
1 (5)
1 (5)
1 (5)
-
-
-
-
V01-X59, Y85- Accidents (unintentional
Y86
injuries)
-
-
-
-
E10-E14
Diabetes mellitus
-
-
-
-
G30
Alzheimer’s disease
-
-
-
-
J10-J18
Influenza and
pneumonia
-
-
-
-
N00-N07, N17- Nephritis, nephritic
N19, N25-N27 syndrome and nephrosis
-
-
-
-
A40-A41
-
-
-
-
U-3, X60-X84, Intentional self-harm
Y87.0
(suicide)
-
-
-
-
K70, K73-K74
Chronic liver disease
and cirrhosis
-
-
-
-
I10, I12, I15
Essential hypertension
and hypertensive renal
disease
-
-
-
-
G20-G21
Parkinson’s disease
-
-
-
-
U01-U02, X85Assault (homicide)
Y09, Y87.1
-
-
-
-
11 (52)
8 (38)
14 (74)
3 (16)
3 (14)
3 (14)
-
-
21 (100)
21 (100)
19 (100)
19 (100)
R00- R99
Septicemia
Symptoms, signs and
abnormal clinical and
laboratory findings, not
elsewhere classified
All other causes
(residual)
Totals
Table 3. Physician-determined and software-generated underlying cause of death categories for each survey group
based on the WHO ICD-10 classification.
Although the effect size was large (74% - 52% = 22%; OR 0.39, 95% CI 0.10-1.49), the
Chi square analysis showed no statistical difference between the rates for responders
16
given version A over version B [χ2 (1, N = 40) = 1.932, p = 0.165] due to the small
sample size.
Open format (version A)
Structured format (version B)
Nonspecific (R00-R99)
11 (52%)
14 (74%)
Specific (non-R code)
10 (48%)
5 (26%)
Table 4. Physician-Determined Underlying COD. X 2 (1, N = 40) = 1.932, p = 0.165
After processing with the MMDS software, only 27.5% (11/40) of the respondents’
original death certificates were coded correctly as non-specific causes. Table 5 shows that
the odds of the software-generated underlying COD being “Nonspecific” was higher in
version A (38%) than in Version B (16%), although this was not significant [χ2 (1, N =
40) = 2.489, p = 0.115]. Again, the large effect size (16% difference or OR 3.9, 95% CI
0.7 - 14.9) was not significant due to the small sample size.
Open format (version A)
Structured format (version B)
Nonspecific (R00-R99)
8 (38%)
3 (16%)
Specific (non-R code)
13 (62%)
16 (84%)
Table 5. Software-generated underlying COD. X 2 (1, N = 40) = 2.489, p = 0.115.
Table 6 shows that the physician and MMDS software agreement on the underlying COD
was 65% and the kappa only fair (κ= 0.37).
In this study, all transformations by the MMDS software from the physician-determined
17
κ= 0.37
Software-Generated Underlying COD
PhysicianDetermined
Underlying COD
Nonspecific (R00-R99)
Specific (Non-R Code)
Nonspecific (R00-R99)
11
14
Specific (Non-R Code)
0
15
Table 6. Software-generated underlying COD specificity versus that determined by the physician.
to the software-generated underlying COD category were from nonspecific R codes to the
category of heart disease (I00-I09, I11, I13, I20-I51). These changes occurred in 14 of
the 25 cases (56%) in which an R code was used by the physician as the underlying COD.
Table 7 shows the statistically significant increase in heart disease reported by the
Underlying COD Category
Physician-Determined
n (%)
Software-Generated
n (%)
Diseases of the heart (I00-I09, I11,I13,I20-I51)
10 (25%)
24 (60%)
All others
30 (75%)
16 (40%)
Table 7. Comparison of heart disease diagnosis as the underlying COD category.
MMDS software to that of the physician (OR 4.5, CI 1.7313 - 11.6962).
To find out if physician characteristics were associated with the use of the nonspecific
classification, the physician characteristics in Table 2 were compared by using Fisher’s
exact test. There were no statistical differences between responses by specialty (p=1),
years since medical school graduation (p=.75), or prior death certificate training (p=1).
There was a significant increase (p=.02) in nonspecific R code usage among physicians in
training (intern/resident) compared with those not in training.
18
DISCUSSION
The first question that this study attempted to answer was whether physicians code for
uncertainty in the underlying cause of death when the cause is unclear. This study shows
that overall, 62.5% of physicians used a nonspecific R code for the underlying COD.
The remainder chose a specific diagnosis, suggesting physician reporting may be biased
toward listing a specific disease or diseases rather than nonspecific or unknown causes
when uncertain about the actual cause of death.
Secondly, this study attempted to answer whether physicians would be more likely to
choose an uncertain/nonspecific condition as the underlying COD when given the option,
as in the specific COD sequences in Version B that included uncertain/nonspecific
diagnoses. There was a tendency for physicians to use these nonspecific diagnoses more
in Version B than with the open-ended format of Version A, although these differences
failed to obtain statistical significance due to the low number of respondents.
These results also suggest that while the majority of physicians may code for an
underlying COD category of not elsewhere classified (R00-R99) for a person dying of
undetermined natural causes, software used for analysis of the death certificate for
national statistical reporting may be biased to report the underlying COD category for
these death certificates as heart disease (I00-I09, I11, I13, I20-I51). Although 62.5% of
physicians reported a nonspecific underlying COD, only 25% appeared to report a
19
nonspecific COD after MMDS software transformation. Approximately half of the
original nonspecific CODs were transformed into specific CODs by the software. To
illustrate how this could occur, consider the following coding of the death certificate (Fig.
4):
Fig. 4. Single cause of death without other significant conditions.
The above is the coding suggested by the CDC for the case used in this study. The
MMDS software would code the underlying COD for this death certificate as R99 - Other
Ill-Defined and Unspecified Causes of Mortality. Now consider the equally plausible
cause of death coding for the same case (Fig. 5):
20
Undetermined Natural Causes
Coronary Artery Disease
Fig. 5. Cause of death with significant contributing condition in Part II.
Here the physician only adds the coronary artery disease seen at autopsy to Part II. The
physician-determined COD remains R99; however, the MMDS software now codes the
underlying COD as I25.1 - Atherosclerotic Heart Disease, and this is the code that would
be used for national statistical purposes had this been an actual death certificate.
The 2006 National Mortality Data (CDC/National Center for Health Statistics, 2009)
shows only a 2.9% difference between the top two causes of death – heart disease and
cancer. Considering that 25% of physicians in this study chose heart disease as the
underlying cause of death for the study case, and considering the bias shown for the
MMDS software to report the underlying cause of death as heart disease, one begins to
wonder about the larger ramifications of erroneous cause of death reporting in terms of
public health initiatives, actuarial and insurance-related issues, and dollars spent on
healthcare and research.
21
In conclusion, the results of this pilot study need to be confirmed with a larger sample
size, but this study suggests that heart disease may be over-reported as the underlying
COD, even when the physician makes a reasonable effort to code an uncertain COD
using nonspecific R codes. Whether national statistics for cause of death would be
significantly affected by better coding for uncertainty by physicians (and computer
software) remains to be seen.
22
BIBLIOGRAPHY
Brown, D. L., Al-Senani, F., Lisabeth, L. D., Farnie, M. A., Colletti, L. A., Langa, K. M.,
et al. (2007). Defining Cause of Death in Stroke Patients. The Brain Attack Surveillance
in Corpus Christi Project. American Journal of Epidemiology , 165 (5), 591-596.
CDC/National Center for Health Statistics. (1997, January). Retrieved February 7, 2010,
from http://www.cdc.gov/nchs/nvss/death_certification_problems.htm
CDC/National Center for Health Statistics. (2009, April 17). National Vital Statisics
Reports, Vol 57, No 14 pg. 119. Retrieved March 1, 2010, from
http://www.cdc.gov/NCHS/data/nvsr/nvsr57_14.pdf
CDC/ National Center for Health Statistics. (2009a, September 1). ICD-10 - International
Classification of Diseases, Tenth Revision. Retrieved July 15, 2010, from
http://www.cdc.gov/nchs/icd/icd10.htm
CDC/ National Center for Health Statistics. (2010). Mortality Medical Data System
Version 2010.10. Hyattsville, MD. CDC/ National Center for Health Statistics, Division
of Vital Statistics.
Department of Health and Human Services, CDC. (2003, April). Physician Handbook on
Medical Determination of Death. Retrieved February 22, 2010, from
http://www.cdc.gov/nchs/data/misc/hb_cod.pdf
Heron, H. P., Hoyert, D. L., Murphy, S. L., Xu, J. Q., Kochanek, K. D., & Tejada-Vera,
B. (2009). Table B in Deaths: Final Data for 2006. National Vital Statistics Reports.
National Center for Health Statistics, Hyattsville, MD.
James, D. S., & Bull, A. D. (1996). Information on death certificates: cause for concern?
Jounal of Clinical Pathology, 49, 213-216.
Lakkireddy, D. R., Gowda, M. S., Murray, C. W., Basarakodu, K. R., & & Vacek, J. L.
(2004). Death Certificate Completion: How Well Are Physicians Trained and Are
Cardiovascular Causes Overstated? American Journal of Medicine, 117, 492-498.
Maudsley, G., & Williams, E. M. (1996). 'Inaccuracy' in death certification - where are
we now? Journal of Public Health Medicine, 18 (1), 59-66.
National Center for Health Statistics. (2010, January). Instructions for Classifying the
Underlying Cause-of-Death, ICD-10, 2010, Part 2a. Retrieved March 29, 2010, from
http://www.cdc.gov/nchs/data/dvs/2A_2010acc.pdf
SAS Institute. (2010). SAS Version 9.2. Cary, NC. SAS Institute.
23
Tavora, F., Crowder, C., Kutys, R., & Burke, A. (2008). Discrepancies in initial death
certificate diagnoses in sudden unexpected out-of-hospital deaths: the role of
cardiovascular autopsy. Cardiovascular Pathology , 17, 178-182.
World Health Organization. (1992). International Statistical Classification of Diseases
and Related Health Problems, Tenth Revision. Geneva, Switzerland: World Health
Organization.
24
APPENDIX
25
SURVEY VERSION A
26
Dear physician,
Thank you for taking the time to complete this survey. Please return the completed survey in the
enclosed self-addressed stamped envelope or directly to the investigator. The address for return
is:
David B. Trant, M.D.
3507 La Reforma
Baytown, TX 77521
713 252-6725
If you wish to receive a summary of the results of this study, please let me know. Again, thank
you for your time.
27
Please take a few minutes to fill out this survey on the death certificate completion. This survey
should take about 5-10 minutes. Your answers will be kept confidential. Thank you for your
participation.
Sample Case
A 92-year-old male was found dead in bed. He had no significant medical history.
Autopsy disclosed minimal coronary disease and generalized atrophic changes
commonly associated with aging. No specific cause of death was identified.
Toxicology was negative.
1) Cause of death determination.
Please complete item 32, Parts I and II, of the following portion of a death certificate for the
sample case above (ignore grayed-out portions):
Please turn to the next page.
28
Additional Questions
2) What is your primary medical specialty?
 Family practice
 Internal medicine
 Other (specify): ____________________________
3) How many years has it been since you completed medical school?
4) Are you currently in an internship/residency training program for your specialty
listed above?


Yes
No
5) Have you ever had any formal training in death certificate completion?


Yes
No
6) How comfortable do you feel completing death certificates?
 Very comfortable
 Somewhat comfortable
 Neither comfortable or uncomfortable
 Somewhat uncomfortable
 Very uncomfortable
29
7) The following questions deal with death certificates in general, not the previous
sample case. For the following diseases or conditions, please answer yes or no as to
whether (in your opinion) this condition would ever be acceptable as a single cause
of death on the death certificate, without listing any additional causes or conditions.
Disease or Condition
Yes
No
Cardiopulmonary Arrest


Acute Myocardial Infarction


Undetermined Natural Causes


Cerebrovascular Accident (CVA)


Motor Vehicle Accident (MVA)


Cardiac Arrhythmia


Respiratory Failure


Hypertension


Advanced Age


Thank you for taking the time to complete this survey.
30
SURVEY VERSION B
31
Dear physician,
Thank you for taking the time to complete this survey. Please return the completed survey in the
enclosed self-addressed stamped envelope or directly to the investigator. The address for return
is:
David B. Trant, M.D.
3507 La Reforma
Baytown, TX 77521
713 252-6725
If you wish to receive a summary of the results of this study, please let me know. Again, thank
you for your time.
32
Please take a few minutes to fill out this survey on the death certificate completion. This survey
should take about 5-10 minutes. Your answers will be kept confidential. Thank you for your
participation.
1) Cause of death determination.
Please consider how you would complete the cause of death portion of the death certificate for
the sample case on the next page. While the choices may not reflect exactly the way you would
complete the death certificate, please choose from the table on the next page what you feel is
the single, most appropriate scenario for completing the Cause of Death, item 32 Parts I and
II from the list on the next page (ignore grayed-out areas).
EXAMPLE: If you were to choose Scenario #99 in the table below,
Scenario
#
99.
Item 32, Part I
a.
b.
Acute
Rupture of myocardium myocardial
infarction
c.
d.
Coronary artery Atherosclerotic
thrombosis
coronary artery
disease
the death certificate would be completed as:
Rupture of myocardium
Acute myocardial infarction
Coronary artery thrombosis
Atherosclerotic coronary artery disease
Diabetes, Chronic obstructive pulmonary disease, smoking
Please turn to the next page.
33
Part II
Diabetes, Chronic
obstructive pulmonary
disease, smoking
Sample Case
A 92-year-old male was found dead in bed. He had no significant medical history.
Autopsy disclosed minimal coronary disease and generalized atrophic changes
commonly associated with aging. No specific cause of death was identified.
Toxicology was negative.
Please choose the scenario number from the table below that you feel is the single, most
appropriate scenario for completing the Cause of Death on the death certificate for the sample
case above (see instructions on previous page):
Scenario #
Scenario
#
Item 32, Part I
a.
b.
1
Acute cerebrovascular
accident
2
Cardiac arrhythmia
Atherosclerotic
coronary artery
disease
3
Cardiac arrest
Undetermined
natural causes
4
Undetermined natural
causes
5
Respiratory arrest
6
Undetermined natural
causes
7
Acute myocardial
infarction
Atherosclerotic
coronary artery
disease
8
Ruptured cerebral
aneurysm
Atherosclerosis
9
Advanced age
10
Cardiac arrhythmia
c.
d.
Part II
Advanced age
Congestive
heart failure
Atherosclerotic coronary
artery disease
Coronary artery disease
Acute
myocardial
infarction
Heart failure
34
Atherosclerotic coronary
artery disease
Additional Questions
2) What is your primary medical specialty?
 Family practice
 Internal medicine
 Other (specify): ____________________________
3) How many years has it been since you completed medical school?
4) Are you currently in an internship/residency training program for your specialty
listed above?


Yes
No
5) Have you ever had any formal training in death certificate completion?


Yes
No
6) How comfortable do you feel completing death certificates?
 Very comfortable
 Somewhat comfortable
 Neither comfortable or uncomfortable
 Somewhat uncomfortable
 Very uncomfortable
35
7) The following questions deal with death certificates in general, not the previous
sample case. For the following diseases or conditions, please answer yes or no as to
whether (in your opinion) this condition would ever be acceptable as a single cause
of death on the death certificate, without listing any additional causes or conditions.
Disease or Condition
Yes
No
Cardiopulmonary Arrest


Acute Myocardial Infarction


Undetermined Natural Causes


Cerebrovascular Accident (CVA)


Motor Vehicle Accident (MVA)


Cardiac Arrhythmia


Respiratory Failure


Hypertension


Advanced Age


Thank you for taking the time to complete this survey.
36
Vita
David B. Trant was born in Texas, where he has lived for all of his 51 years except for 6 months in
Iraq in 2008 with the military. He is a Baylor University graduate, followed by a Doctor of
Medicine degree from UTMB. Following a residency in Internal Medicine from Scott & White
Hospital, he practiced in Baytown, TX for 20 years before joining the US Air Force in 2007 as a
Flight Surgeon. He is currently completing a Residency in Aerospace Medicine (RAM) at BrooksCity Base, TX.
Permanent address:
101 Valona Dr., Cibolo, TX 78108
This dissertation was typed by the author.
37