MORGAM Manual

Data Transfer Format: Follow-up for Diabetes Form: 84 Version: 1 Date: 13.10.2012

© National Institute for Health and Welfare and the MORGAM Project investigators Last updated: 13 October 2012 For more information, please contact Kari Kuulasmaa (firstname.lastname@thl.fi)

The purpose of this transfer format is to provide an exact and common format for the MORGAM Participating Centres (MPCs) to transfer follow-up data on type II diabetes mellitus (T2DM) to the MORGAM Data Centre (MDC). Data in the format specified here should be submitted to the MDC for every member of those MORGAM cohorts that are followed up for diabetes. The data should be sent through e-mail, not on paper forms.

Diabetes is of particular interest in the MORGAM Biomarker SubStudy and in the CHANCES project for the elderly, which MORGAM is participating.

Contents

• Format specification
• General instructions
• Specific instructions for each item
• Updates

Format specification

General Instructions

The record format is ASCII fixed length and record size is 54 characters. The position of each data item in the record is given in column "COLUMNS" of this data transfer format. There should be one record of data for every member of each MORGAM cohort.

This format corresponds with the layout of the information on the electronic data file which is transferred, and need not correspond with the format of locally used paper forms or electronic files. Instructions for transferring the data are given in section Data communication between the Participating Centres and the MDC. To avoid errors, special attention should be paid in extracting these data items from the local data set.

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

Blank fields are not allowed in the record.

Instructions for making corrections to data that have already been sent to the MDC are given in Section Data communication between the Participating Centres and the MDC.

Please contact the MDC for instructions if you cannot provide information as specified in this document or 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 data transfer from the MPC to the MDC.

Number 84 indicates the "Data transfer format: Follow-up for diabetes".

Enter the version number from the heading of the "Data transfer format: Follow-up for diabetes" which you are using. If the version number of the data transfer format which you are using is not "1", these instructions do not correspond to the format you are using. Check that you are using the valid version of the format.

Items CENTRE...SERIAL

These are key items used for merging the different records of the same individual. Please make sure that the codes are identical with those used for the same person in the "Data transfer format: MONICA survey data".

Code 88 (irrelevant). The purpose of this item is to reserve fixed columns for the key items in all data transfer formats. This is a key item in the event data formats, but irrelevant for the other data transfer formats.

The first two columns are for the month; code 01 - 12, or code 99 if the month is not known. Enter the year of birth, in full four characters, in the last four columns. If the year of birth is not known, which should be very rare, derive the year of birth from an estimate of the age.

This item is the same as item MBIRTH of the "Data transfer format: MONICA survey data", and it will be used for double checking the key items. If you compile the data for this record from various sources, please extract the data for this item from a different source than for the MONICA survey record.

This item is the same as item SEX of the "Data transfer format: MONICA survey data", and it will be used for double checking the key items. If you compile the data for this record from various sources, please extract the data for this item from a different source than for the MONICA survey record.

Items DIAB1_FU...ICDVER: Follow-up using documented clinical diagnosis

Code 1 if follow-up of the cohort was based on medical records, clinical diagnosis or other medical documentation. Examples of such follow-up are:

• systematic validation of self-reported diabetes against medical records; and
• linkage of the cohort to hospitalization registers, possibly complemented by linkage to drug prescription registers.

This code should be used at least by the cohorts which have systematic validation of self-reported diabetes against medical records or linkage of the cohort to hospital discharge records during follow-up. Self-reported diagnosis as the only information source is insufficient during follow-up. However, self-reported information can be used for diabetes diagnosed before the baseline examination (i.e.  before the examination round in which the person entered the study) if other data sources are unavailable.

The following information should be provided, prior to the data transfer, for the cohort description in the MORGAM internal web site:

• the data sources;
• follow-up procedures;
• diagnostic procedures; and
• any information on the coverage of the follow-up and the quality of the diagnosis, including references to validation studies if available.

Code 2 if T2DM was not followed up in the cohort using documented clinical diagnosis.

Code 1 if T2DM was diagnosed in the person before or during follow-up. Self-reported information can be used as the only data source only for diabetes diagnosed before the baseline examination (i.e.  before the examination round in which the person entered the study).

Code 2 if no T2DM was diagnosed in the person or it is not known whether or not the person had T2DM.

Each MPC should decide on the exact definition of T2DM for their cohorts. The definition should be added, prior to data transfer, to the cohort description in the MORGAM internal web site.

When routine clinical and death certificate diagnoses are used for the diagnosis of T2DM, the relevant ICD codes are usually

• ICD-8: 250
• ICD-9: 250
• ICD-10: E11.

When necessary, the MPC should adjust these to the diagnostic practices and possible national adaptations of ICD.

The exit takes place when the earliest one of the following occur:

• T2DM is diagnosed (i.e. DIAB1_STATUS = 1) first time in the person. The date of diagnosis should be coded here even if it takes place before the baseline examination. (However, see instructions for code 99999999 below);
• The person dies;
• The person is alive at and has not had T2DM before the fixed end-date of a follow-up period or the individual end-date of follow-up, such as date of questionnaire return or date of interview;
• The person is lost to follow-up. Most likely reasons are: change of contact information, emigration to another country or refusal to participate in the study any longer.

For persons lost to follow-up right after baseline, or if there is no follow-up data available, code the date of baseline examination (i.e. DEXAM of the first ROUNDS when the person entered the study).

If  T2DM was diagnosed before the baseline examination and nothing else is known about the date of the diagnosis, then DIAB1_EXIT should be coded 99999999. Otherwise missing data are not accepted. If the exact date is not known, provide the best estimate. For example, if only the month of diagnosis is known, code 15 in the first two columns. If the person was lost to follow-up and there is no other evidence about the date when this happened, use the mid point between the day when the person was last known to be under follow-up for non-fatal events and the date when the loss to follow-up was observed.

Note: The principles of coding DIAB1_EXIT differ from that of items EXDATEC and EXDATES for the exit from the follow-up for non-fatal coronary and stroke events. In case of the disease, the date of diagnosis is coded for DIAB1_EXIT whereas in EXDATEC and EXDATES the end of follow-up assuming no disease event is always coded. The more simple coding for DIAB1_EXIT is made possible by the fact that we are interested only of the first diagnosis of T2DM, but we are interested also in recurrent coronary and stroke events.

Items DIAB2_FU...DIAB2_status: Follow-up based on measured glucose or HbA_1c in a cohort re-examination

Code 1 if follow-up for T2DM was based on oral glucose tolerance test or measurement of fasting glucose or glycated haemoglobin (HbA_1c) and on (possibly self-reported) data on medication for diabetes in re-examination(s) of the cohort.

If code 1 is used, the used re-examination measurements and the relevant questionnaire items should be provided in the cohort description in the internal MORGAM web site.

Code 2 if T2DM was not followed up in the cohort using measured glucose or HbA_1c in a re-examination.

Code 1 if at least one of the following was observed in the baseline or a re-examination:

• 2-h plasma glucose ≥ 11.1 mmol/l (200mg/ml) during an oral glucose tolerance test (OGTT). (Ideally, the test should have been performed as described by the World Health Organization, using a glucose load containing the equivalent of 75g anhydrous glucose dissolved in water.)
• Fasting plasma glucose ≥ 7.0 mmol/l (126 mg/dl). Fasting is defined as no caloric intake for at least 8 hrs.
• HbA_1c ≥ 48 mmol/mol (6.5%);

OR

• the person is currently under drug treatment for diabetes.

Code 2 if relevant tests were done but the results did not meet the criteria for T2DM.

If DIAB2_STATUS = 1, code here the date of the first examination where T2DM was diagnosed.

If DIAB2_STATUS = 2, code here the date of the latest examination where a test required for the diagnosis of diabetes was taken.

Missing data are not accepted.

Items DIAB3_FU...DIAB3_status: Follow-up based on self-reported diagnosis

Code 1 if follow-up of the cohort was based on self-reported diagnosis, without further validation.

This code can be used by the cohorts which have these data available and do not have data with reasonable coverage for DIAB1_FU or DIAB2_FU. The question used for the self-reported diagnosis should be provided, prior to the data transfer, for the cohort description in the MORGAM internal web site. The question is usually the same as for data item HIST2DM2 of Form 32. If this is not available, data item HISDIAB of Form 21 can be used. However, gestational diabetes should be excluded from DIAB3_FU whenever possible.

Code 2 if T2DM was not followed up in the cohort using documented clinical diagnosis.

Code 1 if at T2DM was reported at baseline or during follow-up.

Code 2 if the question was asked but T2DM was not reported during follow-up.

If DIAB3_STATUS = 1, code here the date when T2DM was diagnosed. If the date was not asked or is otherwise not available, code the date when diabetes was self-reported.

If DIAB3_STATUS = 2, code here the date of the latest examination where diabetes was asked.

Missing data are not accepted.

Updates