MONICA Manual, Part IV, Section 1

Event Registration Data
CORE DATA TRANSFER FORMAT - CORONARY EVENTS
Form: 01
Version: 3         3.5.86
ITEM NAME SPECIFICATION AND CODES CHARACTERS COLUMNS
1 FORM Transfer format identification |_0|_1| 1 to 2
2 VERSN Format version |_3| 3
3 CENTRE MONICA Collaborating Centre |__|__| 4 to 5
4 RUNIT MONICA Reporting Unit |__|__| 6 to 7
5 SERIAL Serial number |__|__|__|__|__|__|__| 8 to 14
6 DREG Date of registration (day,month,year) |__|__||__|__||__|__| 15 to 20
7 SEX Sex
1 = male
2 = female
|__| 21
8 DBIRTH Date of birth (day, month, year) |__|__||__|__||__|__| 22 to 27
9 DONSET Date of onset of event (day, month, year). For a crescendo or indistinct onset, complete 'month' and 'year' but code 'days' using 99 |__|__||__|__||__|__| 28 to 33
10 MANAGE Management
1 = in hospital
2 = in nursing home
3 = at home by a doctor
4 = medically unattended
5 = other medical consultation without bed rest, in hospital or at home
9 = insufficient data
|__| 34
11 SURVIV Survival at 28 days
1 = yes
2 = no
9 = insufficient data
|__| 35
12 SYMPT Symptoms of a coronary event
1 = typical
2 = atypical
3 = other
4 = none
5 = inadequately described
9 = insufficient data
|__| 36
13 ECG ECG findings
1 = definite
2 = probable
3 = ischaemic
4 = other
5 = uncodable
9 = insufficient data
|__| 37
14 ENZ Serum enzymes
1 = abnormal
2 = equivocal
3 = non-specific
4 = normal
5 = incomplete
9 = insufficient data
|__| 38
15 NECSUM Necropsy findings summary
1 = definite
2 = equivocal
4 = negative
8 = alive at 28 days, or no necropsy performed
9 = insufficient data
|__| 39
16 DIACAT Diagnostic category
1 = definite
2 = possible
3 = ischaemic cardiac arrest
4 = none
9 = insufficient data
|__| 40
17 IATRO Possible iatrogenic event
1 = yes
2 = no
9 = insufficient data
|__| 41
18 NUMECG Number of ECGs
0 = none
1 = 1
2 = 2
3 = 3
4 = 4 or more
9 = insufficient data
|__| 42
19-21 Clinical or death certificate diagnosis (ICD-8 or 9 codes)
19 CLIND1 Main clinical condition or underlying cause of death |__|__|__|__| 43 to 46
20 CLIND2 Other clinical condition or other cause of death (if different from item 19) |__|__|__|__| 47 to 50
21 CLIND3 Other clinical condition or other or secondary cause of death |__|__|__|__| 51 to 54
22 PREMI Previous myocardial infarction event (optional codes - use with caution)
(1 = yes, definite, previous record reviewed)
(2 = yes, possible, previous record reviewed)
3 = yes, previous record reviewed, not categorised
(4 = yes, from ECG)
5 = yes, undocumented
6 = no, documented, complete medical records available
7 = no, undocumented
9 = insufficient data
|__| 55
Items 23-29 are for FATAL CASES ONLY. If the person did not die within 28 days (that is, if item 11 has been coded 1 or 9), complete items 23-29 of this record with codes 8, 88, etc.
23 DDEATH Date of death (day, month, year) |__|__||__|__||__|__| 56 to 61
24 ESTST Apparent survival time in the event
1 = < 1 hour (known)
2 = 1-23 hours 59 minutes (known)
3 = > = 24 hours (known)
4 = not known, probably < 24 hours
5 = not known, probably > = 24 hours
8 = alive at 28 days
9 = insufficient data
|__| 62
25 ACCST Accurate survival time in the event: days |__|__| 63 to 64
hours |__|__| 65 to 66
mins |__|__| 67 to 68
26 NECP Necropsy performed
1= yes, routine
2= yes, medico-legal
4= no
8= alive at 28 days
9= insufficient data
|__| 69
27-29 Necropsy diagnoses (ICD-8 or 9 Codes)
27 NECD1 Direct cause of death |__|__|__|__| 70 to 73
28 NECD2 Other disease or condition |__|__|__|__| 74 to 77
29 NECD3 Other disease or condition |__|__|__|__| 78 to 81
30 HISIHD History of chronic ischaemic heart disease prior to present event
1= yes
2= no
8 = not relevant, alive at 28 days
9= insufficient data
|__| 82
31 ICDVER Version of ICD used for diagnoses
1= ICD-8
2= ICD-9
|__| 83

Note for the HTML-version: These instructions were extracted word to word from Version 3 of Form 01, which was part of the December 1986 revision of the MONICA Manual. Therefore, references to other sections of the Manual also refer the December 1986 revision, which has not been converted to HTML.


Instructions

The purpose of this transfer format is to provide an exact and common format for MONICA Collaborating Centres (MCCs) to transfer the Core Data on coronary events to the MONICA Data Centre (MDC). The data should be sent on magnetic tapes, not on paper forms. This format therefore corresponds with the layout of the information on magnetic tape and need not correspond with the format of locally used paper forms, although the information available on the latter has to be convertible to the former. Instructions for data transfer on magnetic tapes are given in Section 10: Data Transfer on Magnetic Tapes to the MONICA Data Centre. To avoid errors, special attention should be paid in extracting these data items from the local data set.

Compared to the pooling record of MONICA Memo 30 (CVD/MNC/84.1, page 26), four items have beed added here: Format version, MONICA Reporting Unit, Date of Registation and ICD Version. (If data is not available for the Date of Registration for the early years of event registration, act according to the specific instructions for that item).

General Instructions

The ITEM NAME on the document is a computer variable name used for the item by the MDC.

The COLUMNS indicate the columns in which the code for the item is to appear in the record on the magnetic tape. Data for different events must be written on different records. It is recommended that the MONICA Collaborating Centres (MCCs) use records long enough to include all coronary event data. If that is possible, the data for an event should be split into two records according to the instructions given in the Description of Data Collection Procedures for the WHO MONICA Project: Characteristics of the Tape.

Blank fields are not allowed in the magnetic tape record. Permissible characters are 0,1,2,3,4,5,6,7,8,9.

Instructions for making corrections to data that have already been sent to the MDC are given in the Section 4.3.6.

Please contact the MDC for instructions if you cannot provide information as specified in this document, and contact the Quality Control Centre for Event Registration in Dundee if you have any problems with the interpretation of the coding for any specific items.

Specific instructions for each item

Follow these instructions carefully when creating a computer file for the transfer from the MONICA Collaboration Centre (MCC) to the MONICA Data Centre. Please ensure that the instructions are for the version of the Core Data Transfer format being used. Specific instructions are listed by item below.

Item 1

1 FORM Transfer format identification |_0|_1| 1 to 2

Enter 01 to indicate CORE DATA TRANSFER FORMAT, CORONARY EVENTS.

Item 2

2 VERSN Format version |_0|_3| 3

Enter the version number that is being used by your MONICA Collaborating Centre. If the number is not 3, these instructions do not correspond to the format you are using. Check that you are using the valid version of the format.

Item 3

3 CENTRE MONICA Collaborating Centre |__|__| 4 to 5

Enter the official MONICA Collaborating Centre code number as it appears in Appendix I: Official MONICA Collaborating Centres and Reporting Unit Names and Code Numbers. If your centre is not listed, or is listed erroneously in this appendix, contact the MDC for instructions.

Item 4

4 RUNIT MONICA Reporting Unit |__|__| 6 to 7

Enter the official MONICA Reporting Unit code number as it appears in Appendix I. Even if your centre has only one Reporting Unit, please enter the appropriate code number here.

Item 5

5 SERIAL Serial number |__|__|__|__|__|__|__| 8 to 14

Enter here the 7-digit serial number of the event for which the record has been completed. Each serial number issued must be unique within each MONICA Reporting Unit and within each register (stroke register or coronary event register). Different MONICA Reporting Units and different registers may use the same serial numbers. However, the serial numbers within a Reporting Unit and register must be different for each calendar year of event registration. Check that the serial number entered is correct.

Item 6

6 DREG Date of registration (day,month,year) |__|__||__|__||__|__| 15 to 20

Enter the date that this specific coronary event came to the attention of the MCC and was allocated a serial number. The point in the registration procedure at which this occurs may vary from centre to centre. It should be defined within each centre and not changed, so that the delay time from DONSET to DREG can be monitored.

The first two columns are for the day; code 01-31 for specific dates, or code 99 if the day is not known. The next two columns are for the month; code 01-12, or code 99 if the month is not known. The last two columns are for the year, but only the last two digits are entered and the first two digits (19) are not entered. If the year of registration is not known, which may happen in attempting to record this new item retrospectively for old registrations, code 99 in the last two columns.

Item 7

7 SEX Sex
1= male
2= female
|__| 21

All cases that are registered must be allocated to the male or female sex. If it is not possible to decide on the sex of a case that case cannot be registered in the study as it cannot be allocated to an age and sex group for analysis.

Item 8

8 DBIRTH Date of birth (day, month, year) |__|__||__|__||__|__| 22 to 27

Enter the exact date of birth. The first two columns are for the day of birth; code 01 - 31 for specific dates, or code 99 if the day is not known. The next two columns are for the month of birth; code 01 - 12, or code 99 if the month is not known. The last two columns are for the year, but only the last two digits are entered and the first two digits (19) are not entered. If the year of birth is not known, use an estimate of the age to derive a year of birth and code that. Records with the year of birth entered as 99 (not known) are not acceptable as they cannot be allocated to an age group for analysis.

Item 9

9 DONSET Date of onset of event (day, month, year). For a crescendo or indistinct onset, complete 'month' and 'year' but code days using 99 |__|__||__|__||__|__| 28 to 33

Enter the exact date of onset of the coronary event. Onset is the onset of the acute symptoms of the coronary event (or, in their absence, the fatal collapse of the person). Where the patient has vague or intermittent symptoms followed by prolonged more severe symptoms, followed by a call for medical help, the time of onset will be the time of onset of the prolonged symptoms. Where several attacks of symptoms occur and each of these attacks could qualify as a possible onset, the onset should be timed from the onset of the first typical event of chest pain lasting more than 20 minutes. Where the patient has vague or intermittent or otherwise atypical symptoms (see item 12) before calling medical help, and then has typical symptoms after being seen, then the time of the onset should be that of the symptoms that led to a medical consultation. Where there is a vague onset and a slow increase in severity of symptoms over several days, that is a crescendo onset, then it will not be possible to time the onset accurately and the days of the month of onset should be coded 99.

In cases of sudden death presenting with a fatal collapse, the time and date of onset will be the same as that for death. Where a person is found dead, use circumstantial evidence to estimate the most likely time (and therefore date as this may be overnight) of onset and death. If the person has not been seen for some time, and is found dead, with no circumstantial evidence of when the fatal event occurred, then estimate the time and date of onset (and of death) as intermediate between the time the person was last seen and the time the body was found. (MCCs should establish quality assurance procedures for standardizing the coding of similar problems to this, such as keeping a file of problem cases and how they were coded, and having a review committee.)

If the date of onset is known, enter 01-31 in the first two columns and 01-12 in the third and fourth columns for day and month of onset, and the year (19--) in the fifth and sixth columns. If the exact day of onset is insufficiently known, enter 99 in the days column. If there is a crescendo, indistinct or vague onset extending over several days enter 99 in the days column. It should always be possible to allocate a month and year of onset so these columns should always be specifically coded.

Item 10

10 MANAGE Management
1 = in hospital
2 = in nursing home
3 = at home by a doctor
4 = medically unattended
5 = other medical consultation without bed rest, in hospital or at home
9 = insufficient data
|__| 34

Code 1 (in hospital) if a medical consultation occurred after the onset of the event and a decision was made to refer or admit the patient as an inpatient and the patient reached hospital alive. Include also patients whose onset of symptoms occurred when they were already in hospital.

Code 2 (nursing home) if there was a medical decision to manage the patient in a nursing home and the patient arrived there alive, or alternatively if he or she was already a patient there. Local definitions should be used in each MCC to decide what is a nursing home and what is a hospital.

Code 3 (at home by a doctor) if there was a medical consultation in the event and a decision by the doctor to manage the patient resting at home.

Code 4 (medically unattended) where no decision on management could be taken because the patient was already dead or in cardiac arrest when first seen by a doctor.

Code 5 (other medical consultation without bed rest, in hospital or at home) where the patient was seen in the event by a doctor but, because death occurred too rapidly or because the event was not diagnosed at the time or because recognition occurred some time after onset, no decision was made to admit the patient for bed rest or to order rest at home, or the patient died in transit.

Code 9 (insufficient data) if information is inadequate to allocate another code.

Item 11

11 SURVIV Survival at 28 days
1 = yes
2 = no
9 = insufficient data
|__| 35

The 28 days' survival period starts from the day when the symptoms started. The 28-day period is calculated form the date of onset of symptoms, (DONSET). The day of onset is day zero.

In cases where one or more reinfarctions occur during the 28 days' period the counting of the 28 days' survival period must start from the date of onset of the first suspected event.

Code 1 (yes) if the survival period is 28 days, that is if the person is alive at the midnight between the 27th and 28th day after the day of onset. Thus the event is fatal if DDEATH - DONSET < 28, and the event is non-fatal if the difference is 28 or more.

Code 2 (no) if the survival period is 27 days or less.

Code 9 (insufficient data) in cases where survival at 28 days is not known. This will occur if the patient is lost to follow-up or there is difficulty in defining the date of onset, DONSET or the date of death, DDEATH or both. To avoid the latter problem measure survival from the date of start of hospital or medical care in cases with an indistinct onset. Try to record an estimate of survival time in all fatal cases, if it is possible.

Item 12

12 SYMPT Symptoms of a coronary event
1 = typical
2 = atypical
3 = other
4 = none
5 = inadequately described
9 = insufficient data
|__| 36

The patient may have one or more episodes of symptoms in the 28 days' survival period following the onset (see item 9).

Code 1 (typical symptoms) when chest pain is present and characterised by:

  1. duration of more than 20 minutes, and
  2. no definite non-cardiac, or cardiac non-atherosclerotic cause.

Any synonym for pain is acceptable such as "pressure", "discomfort", "ache".

If a patient has an onset of acute symptoms that are not typical but subsequently (during the 28 days' survival period) has a recurrence of acute symptoms that are typical, then code the symptoms as 1 (typical). In such cases the date of onset, DONSET, should be that of the first acute symptoms that led to medical consultation.

If a patient has symptoms that are typical, additional symptoms such as a shock, syncope and left ventricular failure will not make those symptoms atypical.

If symptoms are otherwise typical but the duration is not stated, then code 5 (inadequately described). The duration can be assumed to be 20 minutes and the symptoms considered as typical if there are statements in the history implying that the pain lasted while something else was going on, or until something else happened (such as arrival at hospital,  fatal collapse, administration of analgesic by medical attendant) or if the pain is described using words like "protracted" or "continuous", or if the pain continued despite self-administration of drugs.

Code 2 (atypical) means pain that was not typical but there was

  1. one or more of the following conditions present

AND

  1. the absence of cardiac disease other than ischaemic heart disease

AND

  1. no definite non-cardiac cause.

Atypical pain would be pain recorded as of short duration or intermittent with each bout lasting for less than 20 minutes, or pain at an unusual site (upper abdomen, arms, jaw, neck).

Fatal collapse should not be considered as syncope. Syncope should be reversible. Typical chest pain leading to syncope should be coded as typical (see above).

Code 3 (other symptoms) when symptoms are well described but do not satisfy the criteria for typical or atypical. Symptoms due to a definite non-cardiac cause or to a definite non-atherosclerotic cardiac cause (such as pericarditis) should be coded 3.

Code 4 (no symptoms) in non-fatal cases if the patient reported no symptoms in the attack, and in fatal cases if the eyewitnesses of the fatal collapse state that the individual was completely normal and uncomplaining before the moment of death.

Code 5 (inadequately described symptoms) for cases otherwise satisfying criteria for typical pain, but in which the duration of the pain is not described, so that it is not possible to classify the symptoms as typical.

Code 9 (insufficient data) if information on the presence or character of symptoms is inadequate to allocate another code.

Item 13

13 ECG ECG findings
1 = definite
2 = probable
3 = ischaemic
4 = other
5 = uncodable
9 = insufficient data
|__| 37

Because of their length and complexity, coding rules for this item are given separately in 4.3.3, reproduced from MONICA Memo 30.

Item 14

14 ENZ Serum enzymes
1 = abnormal
2 = equivocal
3 = non-specific
4 = normal
5 = incomplete
9 = insufficient data
|__| 38

Each MCC should find out and define, with the help of their local hospital laboratories, (a) the cardiac enzyme tests employed, and (b) the upper limit of normal for each test in each laboratory. Use the HOSPITAL ENZYME USE REPORTING FORM at least once a year to update this information.

For quality control, record the actual enzyme test values on the coronary event forms of your MCC, although those values are not transmitted to the Data Centre.

Code 1 (abnormal) if at least one reading is more than twice the upper limit of normal when measured within 72 hours or within 3 calendar days of onset of symptoms, admission to hospital, or of any recurrence of acute symptoms during the 28-day follow-up period from the original date of onset.

Code 2 (equivocal) when serum enzyme levels are raised but to less than twice the upper limit of normal, when measured within the relevant time period.

Code 3 (non-specific) if serum enzyme levels are raised to more than twice the upper limit of normal, but there are probable explanations other than myocardial infarction, such as liver disease, infections, defibrillation or surgery.

Code 4 (normal) when the enzyme tests are done within the relevant time period and reported adequately and the levels are within the limits of normal.

Code 5 (incomplete) where tests are done but not within 72 hours of onset of acute symptoms or any recurrence.

Code 9 (insufficient data) when serum enzyme tests have not been done or are unavailable.

Note: MCCs differ in the coding of serum enzyme results which are more than twice the limit of normal although taken more than 72 hours or three calendar days from the onset. Some centres code these as 5 (incomplete). Others, because of the difficulty of ascertaining recurrence of symptoms, and because some cardiac enzymes may remain elevated for this time or longer, code them 1 (abnormal). They reserve code 5 (incomplete) for tests done out of time that were either within normal limits or below twice the upper limit of normal. This is a rare problem and centres should make their own rules explicit and stick to them.

Item 15

15 NECSUM Necropsy findings summary
1 = definite
2 = equivocal
4 = negative
8 = alive at 28 days, or no necropsy performed
9 = insufficient data
|__| 39

The results of necropsy recorded also in items 27, 28, 29 (NECD1, 2 and 3) provide the information for this summary.

Code 1 (definite) if, recorded at necropsy there was, visible to the naked eye

  1. myocardial infarction:
    (so that item NECD1, NECD2, or NECD3 = 4101)

and/or

  1. recent occlusion of a coronary artery (from antemortem thrombus or haemorrhage into an atheromatous plaque or embolism):
    (so that item NECD1, NECD2, or NECD3 = 4102)

Code 2 (equivocal) when the necropsy record does not show definite evidence (as above) nor does it record any non-cardiac or cardiac, non-atherosclerotic disease causing death but there is

  1. old myocardial infarction (scar):
    (so that item NECD1, NECD2 or NECD3 = 4120

and/or

  1. occlusion or severe stenosis (greater than 50% reduction of lumen) by atheroma of one or more coronary arteries:
    (so that item NECD1, NECD2 or NECD3 = 4142 or 4143)

Code 4 (negative) when there is recorded at necropsy

  1. no definite evidence as described above,

and

  1. evidence of non-cardiac or cardiac non-atherosclerotic disease causing death.

Code 8 (not relevant) if the patient is still alive at the end of the 28 days survival period or if necropsy was not done.

Code 9 (insufficient data) when the results of the necropsy were not obtained.

Item 16

16 DIACAT Diagnostic category
1 = definite
2 = possible
3 = ischaemic cardiac arrest
4 = none
9 = insufficient data
|__| 40

Note that codes 1,2 and 4 can apply to fatal and non-fatal cases, code 3 to non- fatal cases only and 9 to fatal cases only. Because of their length, coding rules for item 16 are not given here but are stated in Section 4.3.3, based on the  MONICA Protocol 1983 and MONICA Memos 30 and 40, updated.

Item 17

17 IATRO Possible iatrogenic event
1 = yes
2 = no
9 = insufficient data
|__| 41

Fatal or non-fatal events are considered as possible iatrogenic events if they occur less than 3 days after the following procedures:

  1. surgery requiring anaesthesia,

or

  1. intravascular manipulations involving the target organs such as:
    1. angiography,
    2. angioplasty or
    3. intra-arterial thrombolytic treatment

This designation implies a temporal relationship to the procedure but not necessarily a causal one. Note that other medical procedures that may precede the onset of the event should not be coded as 1 (yes) however suspicious the circumstances. The duration of the 3-day period is calculated by subtracting the date of the procedure from the date of onset of the event.

Code 1 if the coronary event occurred 0, 1 or 2 days after a procedure defined above.

Code 2 if no such medical procedure preceded the coronary event, or if it occurred 3 or more days beforehand.

Code 9 if data are insufficient

Item 18

18 NUMECG Number of ECGs
0 = none
1 = 1
2 = 2
3 = 3
4 = 4 or more
9 = insufficient data
|__| 42

The number of ECGs is the number of multiple lead electrocardiographic records made in or just before (that is, less than 28 days before) the coronary event that were available for coding by the MCC staff. Records missing from the medical record and rhythm strips should not therefore be counted.

Item 19 to 21

19-21 Clinical or death certificate diagnosis
19 CLIND1 Main clinical condition or underlying cause of death |__|__|__|__| 43 to 46
20 CLIND2 Other clinical condition or other cause of death (if different from item 19) |__|__|__|__| 47 to 50
21 CLIND3 Other clinical condition or other or secondary cause of death |__|__|__|__| 51 to 54

Code these items according to the International Classification of Diseases, Injuries and Causes of Death (ICD) 9th Revision, or 8th in those few MCCs where the 8th is still in use. Do not code Procedures or Operations as the codes for these are often indistinguishable from entirely different diseases. Code the full 4-digit code or if there is only a 3-digit code, left justify the coding and insert a 9 in the fourth (final) column. If there are fewer than three disease codes, enter 9999 in the unused CLIND fields.

For fatal events where both clinical diagnoses (e.g. hospital discharge diagnoses) and death certificate diagnoses are available, the death certificate diagnosis should take precedence.

In the case of death certificate diagnoses, the coding should follow the sequence shown in option a) below if this is at all possible. This will enable the MCC to compare the MONICA registration diagnoses with the routinely reported mortality figures, based on the underlying causes of death. Some MCCs may have to follow other and less satisfactory rules for coding different diagnoses. Each MCC should follow its own rules and follow them consistently while coding the results for deaths in any calendar year, and should not change them without considering the effects of such a change on any subsequent analysis of trends.

  1. Where the underlying cause of death has been coded, or can be coded according to national coding practice, code this underlying cause of death first in CLIND1. Code the other diagnoses on the death certificate in CLIND2 and CLIND3. If there are four or more diagnoses on the death certificate, and the diagnosis that led to registration appears as the fourth or an associated cause of death, then code that diagnosis in CLIND3 to make sure that it is not left off the record.

Where the MCC has a copy of the death certificate, either without the ICD codes coded according to national coding practices, or the ICD codes are present, but national coding routines cannot be followed to find what the underlying cause of death would be, then the alternatives are:

  1. code the diagnoses according to the sequence in which they appear on the death certificate, which is preferred to-
  2. code first the diagnosis that led to registration of the event.

For non-fatal events record the clinical diagnoses here. Ordinarily these will be the major hospital discharge codes, but if none is available such as when a patient is managed at home, or discharge coding has not been done, the MCC should assign up to three ICD codes to the clinical diagnoses of the attending doctors. In general, code the clinical diagnoses in the sequence in which they appear on the discharge or other documents. However, make sure that the major reason for hospital admission appears first. If there are more than three diagnoses recorded, and the diagnosis that led to registration is not among the first three, then ensure that this diagnosis is coded in CLIND3.

Item 22

22 PREMI Previous myocardial infarction event
(optional codes - use with caution)
(1 = yes, definite, previous record reviewed)
(2 = yes, possible, previous record reviewed)
3 = yes, previous record availabe, not categorised
(4 = yes, from ECG)
5 = yes, undocumented
6 = no, documented, complete medical records available
7 = no, undocumented
9 = insufficient data
|__| 55

MCCs should establish procedures for ensuring that the information, on whether persons whose coronary events are being registered have a history of previous myocardial infarction or not, is as good as possible; but it should be free from the possibility of a biased trend over the 10-year period of registration. This item is important in deciding on the ratio of event rates for first versus recurrent events and special analyses will be made of trends in this. A previous history of infarction is also important in allocating MONICA diagnostic categories to fatal cases. MCCs should try to keep the proportion of coronary events with this item coded 9 (insufficient data) to a minimum, (with the possible exception of non-fatal cases with DIACAT = 4 (none) where it is less important). Special efforts may be needed in fatal cases and other cases where a medical history may not be provided with the record of the current event. However, in order to avoid biases in trends, MONICA registration records held by the MCC must not be used to obtain this information, as there will be no such records at the beginning of the study and 10 years of records at the end. Electrocardiograms from population screening or health checks should also not be used unless these are likely to be equally available throughout the study. Previous history should be decided on the basis of routine records used consistently throughout the study such as:

  1. records present in the hospital treating the current attack and
  2. a defined number of sources in fatal cases.

The date of onset of any previous myocardial infarction should be 28 days before the event being registered or the latter will be part of the earlier event. Five codes, (3,5,6,7,9) are now considered to be core codes, while the others, (1,2,4) are local options, to be used with great caution. If the only available sources of information about previous coronary events are the medical records referring to the current event, then the previous medical history is "undocumented" and the only codes possible are 5,7 and 9. If records of previous medical care or admissions to hospital are filed with the records of the current coronary event or are routinely reviewed then previous coronary events may be "documented" and the codes 1,2,3,4 and 6 are possible. Codes 1,2 and 4 may be used optionally by MCCs which wish to do so, but these categories will be amalgamated with the others for purposes of analysis. They should be used with extreme caution because of the risk of introducing bias over the 10-year period of the study.

Code 1 (optional, yes definite, previous record reviewed) if medical records seen for the current event include records for previous event(s) and one or more of these satisfies the MONICA diagnostic category "definite". Note that MCC registration records for the event must not be used for this purpose.

Code 2 (optional, yes possible, previous record reviewed) if medical records seen for the current event include records for previous event(s) and these do not satisfy the MONICA criteria for "definite" but do do so for the "possible" category. Note that MCC registration records for the event must not be used for this purpose, for the reasons explained above.

Code 3 (yes, previous record reviewed, not categorised) if medical records seen for the current event include older records and they show that the patient previously had a coronary event. The previous coronary event may be definite, possible or ischaemic cardiac arrest, or a suspected but unconfirmed event involving medical care and diagnosis, but not chronic angina pectoris alone. "Not categorised" means that the full MONICA diagnostic evaluation is not done by the MCC to decide whether the event was definite or possible, or the evidence in the record is inadequate for such a categorisation.

Code 4 (optional, yes, ECG) is used when old medical records were not seen, but there is available for review an electrocardiogram dating from before the onset of the current event which shows Q-waves codable in the Minnesota code as 1-1 or 1-2 (except 1-2-6). Electrocardiograms from the current event may not be used for this code. (MCCs using this code will need to satisfy themselves that the possibility of introducing bias can be averted. This could be done if code 4 was used only in the absence of codes 1,2,3,5 and 7. A decision could then be postponed as to whether this code should be amalgamated with the positive or negative codes in any subsequent grouping).

Code 5 (yes, undocumented) if there are no previous medical records seen with those for the current event, but recorded in the medical history of this event is a statement that the patient had already had a definite, possible or suspected myocardial infarction of ischaemic cardiac arrest more than 28 days before the onset of the current event.

Code 6 (no, documented) when continuous or complete medical records are available at the time of registration and these show, in a complete review, that there is no history of a coronary event before the current episode.

Code 7 (no, undocumented) if there are no continuous medical records seen with those for the current episode, or any previous record of a coronary event and the current history states or implies that there is no previous history of a coronary event. These criteria are met by any one of the following statements in the current coronary event or medico-legal records:

  1. that there is no previous history of myocardial infarction or no previous history of coronary heart disease (or synonyms such as heart trouble)
  2. that the patient has never had symptoms like those of the present event
  3. that the patient has had no serious illnesses, or has never been in hospital, or has been previously healthy
  4. that the patient has had certain illnesses or operations without any mention of myocardial infarction among them

Code 9 (insufficient data) if there are no data in the record of the current event which refer positively or negatively to a previous medical history, and there are no other records available which are useable for this purpose.

Item 23

23 DDEATH Date of death (day, month, year) |__|__||__|__||__|__| 56 to 61

Enter the exact date of death using the same format as for DREG. If the patient did not die during the 28 days' survival period, code this item 888888. Note that in legal terms a person is not dead until this has been certified by a doctor. The date and time when this happens may be a long time after the person suffered cardiac arrest and became lifeless, either because the death was not witnessed, or because it took some time for a doctor to be called or for the body to be taken to the hospital. Do not accept the time of death as recorded on medico-legal documents, but estimate the time and date at which the fatal collapse occurred. Note also that unsuccessful attempts at resuscitation do not postpone the time of death for this purpose. Death should be considered as the time at which the irreversible cardiac arrest first occurred, even if the medical attendants or bystanders initiated and continued resuscitation attempts in the hope that it was reversible. Where a person is found dead, use circumstantial evidence to estimate the most likely time (and therefore date as they may be overnight) of death. If the person has not been seen for some time, and is found dead, with no circumstantial evidence of when the fatal event occurred, then estimate the time and date of death as half-way between the time the person was last seen and the time the body was found.

Item 24

24 ESTST Apparent survival time in attack
1 = < 1 hour (known)
2 = 1-23 hours 59 minutes (known)
3 = > = 24 hours (known)
4 = not known, probably < 24 hours
5 = not known, probably > = 24 hours
8 = alive at 28 days
9 = insufficient data
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The apparent survival time in the attack is the time elapsed between the time of onset (see item 9, DONSET) and the apparent time of death (see item 23, DDEATH). Note that estimates are preferable to coding 9 (insufficient data). Note also that the apparent time of death, not the legally certified time of death, should be used. The apparent time of death should not be timed to the end of unsuccessful attempts at resuscitation but to the time of the collapse that initiated them. Fatal collapse is not always witnessed and some degree of interpolation and interpretation of the history is permissible. For example, if the body was found in a situation that suggested that the person was carrying out everyday activities normally until death occurred, it would be reasonable to assume that death had occurred very rapidly after onset. For those found dead in bed it is not possible to assume that no illness symptoms had occurred first, but it may be possible to eliminate survival longer than 24 hours from circumstantial evidence.

Code 1, 2 or 3 if the survival time is known with the required precision to separate these three codes from each other.

Code 4 (probably less than 24 hours) if the time is not precisely known but there is reason to believe that the event lasted less than one day from the onset.

Code 5 (probably more than or equal to 24 hours) if the time is not precisely known but there is reason to believe that the patient probably survived for 24 hours or more.

Code 8 (alive at 28 days) if the patient did not die during the event.

Code 9 (insufficient data) if the survival time is not known at all in fatal cases or if survival status at 28 days is not known. The use of this code should be avoided.

Item 25

25 ACCST Accurate survival time in attack: days |__|__| 63 to 64
hours |__|__| 65 to 66
mins |__|__| 67 to 68

This item is optional and any MCC which does not use it for any of its cases should fill this field with 88 88 88. The field should also be filled with 88 88 88 by all centres for cases alive at 28 days. If this item is being coded by a MCC but there are insufficient data in a particular case, or there was an indistinct onset then complete this item with 99 99 99. This will be true of cases in which Item 24 ESTST has been coded 4, 5 or 9.

Code days (0-27) in the first two columns, hours (0-23) in the third and fourth columns and minutes (0-59) in the fifth and sixth columns. Where death was apparently instantaneous enter 00 00 00. Hours and minutes can be coded with 99 if they are insufficiently known, or the longer time intervals can be rounded to whole numbers of days or hours.

Item 26

26 NECP Necropsy performed
1= yes, routine
2= yes, medico-legal
4= no
8= alive at 28 days
9= insufficient data
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Code 1 if a routine necropsy was performed for medical purposes only (e.g. in a teaching hospital or at the request of the attending doctor).

Code 2 if the necropsy was performed at the request of, or to fulfill the requirements of the medico-legal authority (e.g. police, coroner, etc.).

Code 4 if no necropsy was performed.

Code 8 if the patient did not die within 28 days.

Code 9 if it is not known whether the patient was alive or dead at 28 days, or if it is not known whether or not necropsy was performed.

Item 27 to 29

27-29 Necropsy diagnoses
27 NECD1 Direct cause of death |__|__|__|__| 70 to 73
28 NECD2 Other disease or condition |__|__|__|__| 74 to 77
29 NECD3 Other disease or condition |__|__|__|__| 78 to 81

Code as many diagnoses as you can up to three from the necropsy report. If any of the following findings are present, code them in this order of priority.

ICD-9 ICD-8
(a) Recent myocardial infarction 4101 4101
(b) Recent coronary occlusion 4102 4102
(c) Recent subarachnoid haemorrhage 4301 4301
(d) Recent occlusion of precerebral arteries 4331 4321
(e) Recent cerebrovascular lesion 4311 4311
(f) Recent cerebral arterial occlusion 4342 4332 or 4342
(g) Old myocardial infarction or scar 4120 4120
(h) Chronic occulsion of a coronary artery 4143 4143
(i) Coronary stenosis greater than 50% 4142 4142
(j) Old cerebrovascular lesion 4381 --

Code any other competing cause of death using the ICD code.

If only one diagnosis is given, code it in NECD1, and 9999 in NECD2 and NECD3; if two diagnoses, code them in NECD1 and NECD2, with 9999 in NECD3. If the necropsy was done but it was not possible to review the necropsy report code 9999 in NECD1, 2 and 3. If the patient did not die or if no necropsy was performed although the patient died during the 28 days' survival period, code NECD1, 2 and 3 8888.

If the ICD codes for the necropsy findings are 3-digit codes these should be left-justified in the first three spaces with 9 as the fourth digit.

Item 30

30 HISIHD History of chronic ischaemic heart disease prior to present attack
1= yes
2= no
8= not relevant, (optional code for non-fatal cases)
9= insufficient data
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Code 1 (yes) if the patient had a history of chronic ischaemic heart disease such as:

  1. definite or possible myocardial infarction, that is Item 22, PREMI = 1, 2, 3, 4, 5.
  2. coronary insufficiency or angina pectoris decided on the basis of a review of medical records, in the absence of a firm diagnosis of valvular heart disease or cardiomyopathy.

If a necropsy was done and findings indicate chronic ischaemic heart disease, that alone is not sufficient to code 1.

Code 2 (no) if review of the records gives good reason to presume that the patient did not have clinical manifestations of chronic ischaemic heart disease before the event being registered. In such cases PREMI cannot be coded as 1, 2, 3, 4 or 5.

Code 8 (not relevant, optional code for non-fatal cases) is a code for those MCCs not coding Item 30 on survivors at 28 days. However, MCCs are urged to code Item 30, HISIHD, on all cases, and not to use this code therefore.

Code 9 (insufficient data) when data are insufficient to decide whether there was a history of chronic ischaemic heart disease or not. Code 9 is therefore incompatible with the coding of Item 22 PREMI as 1, 2, 3, 4 or 5 in the same case.

Item 31

31 ICDVER Version of International Classification of Diseases used for diagnoses
1= ICD Eight Revision
2= ICD Ninth Revision
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