RECORD AXIS CODES

The following paragraphs describe the format and application of record-axis 
data.  Part 2f of the Vital Statistics Instruction Manual Series describes 
the TRANSAX process for creating record axis data from entity axis data.

FORMAT:  Each record (or person) axis code is displayed in five bytes.  
Location information is not relevant. The Code consists of the following 
components:

3. Nature of injury flag:  The first byte contains a 0 or 1 with the 1 indicating
                           that the cause is a nature of injury category.

2. Cause category:         The last four bytes represent the ICD-9 cause code.

Again, a maximum of 20 codes are captured on a record for multiple cause
purposes.  The codes are written in a 100-byte field in ascending code number
(5 bytes) order with any unused bytes left blank.

EDIT:  The record axis codes are edited for rare causes and age/cause and
sex/cause compatibility.  Likewise, individual code validity is checked.  The
valid code set for record axis coding is the same as that for entity coding.

RECORD AXIS APPLICATIONS: The record axis multiple cause data set is the basis
for NCHS core multiple cause tabulations. Location of codes is not relevant to
this data set and conditions have been linked into the most meaningful
categories for the certification.

The most immediate consequence for the user is that the codes on the record
already represent mention of a disease assignable to that particular ICD-9
category.  This is in contrast to the entity code which is assigned each time
such a disease is reported on two different lines of the certification.
Secondly, the linkage implies that within the constraints of ICD-9 the most
meaningful code has been assigned.  The translation process creates for the
user a data set which is edited for contradictions, duplicate codes, and
imprecisions.  In contrast to entity axis data, record axis data are
classified in a manner comparable to underlying cause of death classification
thereby facilitating joint analysis of these variables.  Likewise, they are
comparable to general morbidity coding where the linkage provisions of ICD-9
are usually utilized.  A potential disadvantage of record axis data is that
some detail is sacrificed in a number of the linkages.

The  user can take the record axis codes as literally representing the
information conveyed in ICD-9 category titles.  While knowledge of the rules
for combining and linking and coding conditions is useful, it is not a
prerequisite to meaningful analysis of the data as long as one is willing to
accept the assumptions of the axis translation process.  The user is
cautioned, however, that due to special rules in mortality coding, not all
linkage notes in ICD-9 are utilized.  (See Part 2f of the Vital Statistics
Instruction Manual Series.)

The user should proceed with caution in using record axis data to count
conditions as opposed to people with conditions since linkages have been
invoked and duplicate codes have been eliminated.  As with entity data, person
based tabulations which combine individual cause categories must take into
account the possible interaction of up to 20 codes on a single certificate.

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