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FIN-EAS and FIN-WES: Eastern and south-western Finland/FINRISK Study Contributors from the MPC: Veikko Salomaa and Anne Juolevi

© National Institute for Health and Welfare and the MORGAM Project investigators Last updated: 13 February 2009 For more information, please contact Kari Kuulasmaa (firstname.lastname@thl.fi)

Contents

• Cohort identification
• Cohort recruitment and the baseline examination
• End-points followed up
• End of follow-up period
• Follow-up procedures
• Diagnostic procedures
  • at baseline
  • during follow-up
• References
• Updates

Cohort identification

• Country: Finland
• MPC: 20 - FINRISK
  • Administrative centre: Department of Health Promotion and Chronic Disease Prevention, National Public Health Institute, Helsinki, Finland
  • Key personnel: Veikko Salomaa (Principal Investigator), Anne Juolevi, Erkki Vartiainen, Pekka Jousilahti
• RUs:
  • 02 - North Karelia. Former province of North Karelia in eastern Finland (excluding the commune of Kesälahti)
  • 03 - Kuopio Province. Former province of Kuopio in eastern Finland
  • 05 - Helsinki. Town of Helsinki, the capital of Finland and the adjacent town of Vantaa
  • 06 - Turku /Loimaa. Town of Turku and Loimaa district in south-western Finland
  • 07 - Oulu Province. A province covering an area from the Gulf of Botnia to the Russian border in the narrowest part of the country.
• RUAs:
  • FIN-EASa - consisting of RUs 02 and 03
  • FIN-EASb - consisting of RUs 02, 03 and 07
  • FIN-WESa - consisting of RU 06
  • FIN-WESb - consisting of RUs 05 and 06
• Cohorts:
  • Cohorts 01 - Respondents of representative samples of 25-64 years old men and women of RUs 02, 03 and 06. The baseline survey was carried out in 1982.
  • Cohorts 02 - Respondents of representative samples of 25-64 years old men and women of RUs 02, 03 and 06. The baseline survey was carried out in 1987.
  • Cohorts 03 - Respondents of representative samples of 25-64 years old men and women of RUs 02, 03, 05 and 06. The baseline survey was carried out in 1992.
  • Cohorts 24 - Respondents of representative samples of men and women of RUs 02, 03, 05, 06 and 07. The age group considered was 25-64 years in RUs 03, 06 and 07, and 25-74 years in RUs 02 and 05. The baseline survey was carried out in 1997.
  • Cohorts 34 - Complement of Cohorts 24, including the persons of the 1997 survey who were excluded from Cohorts 24 because they were already included in Cohorts 01, 02 or 03. Cohorts 34 can be pooled with Cohorts 24 in analyses which do not involve Cohorts 10, 02 or 03.

Cohort recruitment and the baseline examination

The cohorts were formed by the respondents of representative sample surveys of the RUs. The Nationwide Central Population Register (see Population Information System of the Population Register Centre) was used as sampling frame for the single stage sampling, which was stratified by sex and 10-year age group. The baseline examinations of Cohorts 01, 02 and 03 of RUs 02, 03 and 06 were carried out as part of the WHO MONICA Project, where they were recognised by the codes FIN-NKA (RU 02), FIN-KUO (RU 03) and FIN-TUL (RU 06). The MONICA procedures were used also in the other Cohorts.

The size of the MORGAM cohorts and response rates of the population surveys from which cohorts were derived are:

DNA are available for the members of Cohorts 03 and 24.

End-points followed up

• Deaths: yes
• Non-fatal acute MI: yes
• Unstable angina pectoris: yes, only hospitalized events
• Silent MI: no
• Cardiac revascularization: yes
• Stable angina pectoris: no
• Non-fatal stroke events: yes
• Thromboembolic events: yes, only hospitalized events for Cohorts 03, 24 and 34

End of follow-up period

• Cohorts 01, 02 and 03:
  • Fatal events:
    • 31 December 1998
    • In year 2001 the follow-up was extended to 31 December 2000
    • In year 2003 the follow-up was extended to 31 December 2001
    • In year 2007 the follow-up was extended to 31 December 2005
    • In year 2009 the follow-up was extended to 31 December 2007
  • Non-fatal events:
    • 31 December 1998
    • In year 2001 the follow-up was extended to 31 December 2000
    • In year 2003 the follow-up was extended to 31 December 2001
    • In year 2007 the follow-up was extended to 31 December 2005
    • In year 2009 the follow-up was extended to 31 December 2007
• Cohorts 24 and 34:
  • Fatal events:
    • 31 December 2003
    • In year 2006 the follow-up was extended to 31 December 2004
    • In year 2007 the follow-up was extended to 31 December 2005
    • In year 2009 the follow-up was extended to 31 December 2007
  • Non-fatal events:
    • 31 December 2003
    • In year 2006 the follow-up was extended to 31 December 2004
    • In year 2007 the follow-up was extended to 31 December 2005
    • In year 2009 the follow-up was extended to 31 December 2007

Follow-up procedures

Sources of data

• Register of Causes of Death: Statistics Finland maintains a register of causes of death. The register covers all deaths in Finland or abroad of persons who were residents of Finland at the time of death, regardless of their citizenship. The sources of data for the register are the death certificates and the Population Information System of the Population Register Centre. A death certificate, issued by a physician, is obtained for almost every death. The death certificate follows the international format for death certifications issued by the World Health Organization (WHO). The death certificate data are checked against the data in the Population Information System. Statistics Finland compiles the underlying cause of death using the information on the death certificate and the rules of the International Classification of Diseases (ICD) of the WHO. When necessary, the certifying doctor is consulted. The eighth revision of ICD was used up to 1986, ninth revision from 1987 to 1995 and the tenth revision since 1996.
• Hospital Discharge Register: The National Research and Development Centre for Welfare and Health keeps a national register of all hospitalizations. Among other things, it includes the dates of the hospitalizations and ICD codes of the clinical diagnoses assigned to the patients by the treating doctors. Assessments of the validity of the clinical diagnoses for coronary and stroke events can be found in references [1], [2] and [3]. 
• FINMONICA coronary event and stroke registers: These were population based registers taking part in the WHO MONICA Project. The coronary event register covered RUs 02, 03 and 06 in years 1983-1992. Its upper age limit was 64 years [4]. The coverage of the stroke register was:

  RU	Year	Age group
  02	1982-91	<75
  03	1983-89	<75
  	1990-92	no age limit
  05	not covered
  06	1983-92	no age limit in Turku
  		<75 in Loimaa district
  07	not covered

  For more information on the stroke register see [5].

• FINAMI and FINSTROKE register: The FINMONICA registers were followed by the FINAMI and FINSTROKE registers, which also used the MONICA Procedures. They covered only subsets of the RU areas but had higher upper age limits:

  FINAMI coronary event register
  RU	Year	Age group	Area
  02	1993-94	<75	Joensuu, Ilomantsi, Juuka and Lieksa
  	1995-97	no age limit	Joensuu, Ilomantsi, Juuka and Lieksa
  	1998-2002	no age limit	Joensuu
  03	1993-97, 1999-2002	no age limit	Kuopio
  05	not covered
  06	1993-94	<75	Turku
  	1995-97	no age limit	Turku
  	1998, 2000-2002	after the age of 74, the register covers only those who were born on the odd day of the month	Turku
  07	1993, 1997-2002	no age limit	Oulu

   

  FINSTROKE stroke register
  RU	Year	Age group	Area
  03	1993-97	no age limit	Kuopio, Varkaus, Kiuruvesi, Siilinjärvi
  06	1993-95	<75	Turku
  	1996-98	no age limit	Turku
  02, 05, 07	not covered

• FINMONICA-FINAMI register of cardiac revascularizations: FINMONICA coronary event register aimed to collect all cardiac revascularizations of the residents of  the FINMONICA areas up to the end of the year 1993. Local registration nurses reviewed all available sources for cardiac revascularizations, including patient records, hospital discharge lists and outpatient department visit lists. The computerized Hospital Discharge Register was searched. It included the codes of operations and since 1986 also the codes of invasive procedures like angioplasty. After the year 1994 the notification of revascularizations was done only by the linkage of the MORGAM Cohorts to the Hospital Discharge Register. Since 1994 the Hospital Discharge Register collected information on cardiac revascularizations using a specific data collection form. Local Finnish codes of procedures and operations were used until 1996, and the Nordic NOMESCO Classification of Surgical Procedures since 1997.

Procedures

Everyone in Finland has an unique personal identification code issued by the Local Register Office in collaboration with the Population Register Centre. The cohorts were linked to the FINMONICA, FINAMI, FINSTROKE, Hospital Discharge Register and the Register of Causes of Death using the personal identification code.

Diagnostic procedures

At baseline:

• History of MI:
  • Documented: The cohorts were linked to the FINMONICA coronary event register and the FINAMI register (data since 1983) and to the Hospital Discharge Register (data since 1969). Persons with ICD-8 codes 410 or 411 or with ICD-9 codes 410 or 411 or with ICD-10 codes I20.0, I21 or I22 were considered having a documented history of MI or unstable angina pectoris.
  • Self-reported: An affirmative answer to the question "Have you had a myocardial infarction or heart attack confirmed by a doctor?" was considered as self-reported history of MI.
  • ECG: data not available
  • Rose questionnaire: As specified in item HISMI4 of MORGAM Form 21. This was available for Cohorts 01 and 02 only.
• History of cardiac revascularisation:
  • Documented: The cohorts were linked to the FINMONICA-FINAMI register of cardiac revascularizations (data since 1983).
  • Self-reported: data not available
• History of angina pectoris:
  • Documented: Cohorts 02, 03, 24 and 34 were linked to the computerized national drug reimbursement register maintained by the National Social Insurance Institution. This covers the coronary heart disease cases (angina pectoris, myocardial infarction, ischemic heart disease) since 1986, whose drug reimbursement applications were approved by the National Social Insurance Institution. The data are not available for Cohort 01.
  • Rose questionnaire: data not available
  • Self-reported: For Cohorts 01 and 02, an affirmative answer to an option "Angina pectoris" under the question "Have you during the last year had any of the following diseases confirmed or treated by a doctor?" was considered as self-reported history of angina pectoris. For Cohorts 03, 24 and 34, an affirmative answer to an option "Chest pain in effort (Angina pectoris)" under the question "Have you during the last year had any of the following diseases confirmed or treated by a doctor?" was considered as self-reported history of angina pectoris.
• History of coronary heart disease, type unspecified: not relevant because type-specific information was available.
• History of stroke:
  • Documented: The cohorts were linked to the FINMONICA stroke event register and the FINSTROKE register (data since 1983) and to the Hospital Discharge Register (data since 1969). Persons with ICD-8 codes 430, 431 (excluding codes 431.01, 431.91 of the Finnish adaptation of ICD-8*), 432, 433, 434 or with ICD-9 codes 430, 431, 433 (excluding codes 4330X, 4331X, 4339X of the Finnish adaptation of ICD-9*), 434 (excluding code 4349X of the Finnish adaptation of ICD-9*), 436, 437, 438  or with ICD-10 codes I60, I61, I63, I64 or I69 were considered having a documented history of stroke.
  • Self-reported: An affirmative answer to the question "Have you had a stroke, brain haemorrhage or brain infarction confirmed by a doctor?" was considered as self-reported history of stroke.
• History of Diabetes: For Cohort 01 an affirmative answer to any of three options "Yes, I take insulin injections", "Yes, I take oral hypoglycaemic agents", "Yes, only dietary care" under the question "Do you have diabetes confirmed by a doctor?" was considered as history of diabetes. For Cohorts 02, 03, 24 and 34 an affirmative answer to either of the options "Latent diabetes" or "Diabetes" under the question "Has a doctor sometimes told you that you have diabetes or latent diabetes?" was considered as history of diabetes.

During follow-up:

• Deaths: Final official cause of death codes from the Register of Causes of Death were used for the relevant items of MORGAM Form 25.
• CHD events: For events found in the FINMONICA or FINAMI register, two different diagnostic procedures were used:
  • For the events up to year 1996, the MONICA diagnostic category was used. However, if the MONICA diagnostic category was "no MI", but there was a  clinical diagnosis 411 of ICD-8 or 9 or I20.0 of ICD-10, then the event was coded as unstable angina.
  • For the events since 1997, the AHA/WHF/ESC/CDC/NHLBI definition from year 2003 was used [6]. This is, in essence, an update of the WHO MONICA MONICA definition, extending it to the new biomarkers. The MORGAM diagnostic category was derived from this classification according to the following table:

    AHA/WHF/ESC/CDC/NHLBI 2003 category	MORGAM DGNCAT
    I. Nonfatal events:
    A. Definite MI	1
    B. Probable MI	2
    C. Possible MI	2
    D. Unrecognized MI (not used in FINRISK)
    E. Medical procedure-related event	3
    F. Unstable angina pectoris	4
    G. Stable angina pectoris	7
    Events not qualifying to any of the above	7
    II. Fatal events (hospitalized patients):
    A. Definite MI	1
    B. Probable MI	2
    C. Possible fatal coronary event	2
    Events not qualifying to any of the above	7
    Out-of-Hospital Deaths:
    I. Definite fatal MI	1
    II. Definite fatal IHD	3
    III. Possible fatal IHD	2
    IV. Cardiac death	5
    V. Non-IHD death	7
    VI. Unclassifiable	5

    For the events which were validated using the AHA/WHF/ESC/CDC/NHLBI definition, the source of validation of the diagnosis of acute coronary event was coded for MORGAM as "Other systematic review of diagnostic data".

  For events which were found in the Hospital Discharge Register or the Register of Causes of Death but not in the FINMONICA or FINAMI register, the diagnostic classification was done using the ICD-codes:
  

  Hospital discharge code			MORGAM DGNCAT
  ICD-8	ICD-9	ICD-10
  410	410	I21, I22	3
  411	411	I20.0	4
  other			7
  Official underlying, antecedent or direct cause of death code
  410-414	410-414	I21-I25	3
  795	798	I46, R96, R98, R99	5
  other			7

  Coronary events occurring within 28 days of each other were considered as one event. For events found both in the Hospital Discharge register and the Register of Causes of Death, a coronary event diagnosis was given if it was found in either of them. If several diagnoses were given during a 28-days period the most severe event was used for the classification.

  Unstable angina following a MI was not recorded for MORGAM. The same concerns a non-fatal possible MI following a possible or definite MI and a non-fatal definite MI following a definite MI.

  A separate search of the Hospital Discharge Register was done for cardiac revascularization. When revascularization was done within 28 days of a coronary event, it was recorded as acute event with revascularization. Otherwise it was recorded as revascularization.

• Stroke events, Cohorts 01, 02, 03 (since 1998), 24 and 34: For events found in the FINMONICA or FINSTROKE registers, the MONICA diagnostic category was used. For events which were found in the Hospital Discharge Register or the Register of Causes of Death but not in the FINMONICA or FINSTROKE register, the diagnostic classification was done using the ICD-codes:

  Hospital discharge code or official underlying, antecedent or direct cause of death code			MORGAM DGNCAT
  ICD-8	ICD-9	ICD-10
  430, 431 (excluding codes 431.01, 431.91 of the Finnish adaptation of ICD-8*), 432, 433, 434	430, 431, 433, 434, 436, but excluding codes 4330X, 4331X, 4339X, 4349X of the Finnish adaptation of ICD-9*	I60, I61, I63, I64, I69**	9
  other			4

  Stroke events occurring within 28 days of each other were considered as one event. For events found both in the Hospital Discharge register and the Register of Causes of Death, a stroke diagnosis was given if it was found in either of them.

  Cohorts 03 (up to 1998): The hospital records were reviewed and the MONICA diagnostic classification was done for all events which had ICD-8 or ICD-9 code 430-438 or ICD-10 code I60-I69 in the Hospital Discharge Register or the Register of Causes of Death.

• Thrombo-embolic events: For events found in the Register of Causes of Death or in the Hospital Discharge Register, the diagnostic classification was based on their ICD-codes:

  Hospital discharge code or underlying, antecedent or direct cause of death code			Type of venous thromboembolic event in MORGAM
  ICD-8	ICD-9	ICD-10
  450, 673.9	415, 673.2	I26, O88.2	Pulmonary embolism
  451, 671	451 (excluding 451.0), 671.3, 671.4	I80 (excluding I80.0), O87.1	Deep vein thrombosis
  other			not recorded as thromboembolic event in MORGAM

  Events occurring within 28 days of each other were considered as one event.

* The specification of stroke diagnoses refers to the following codes identifiable in the Finnish adaptation of ICD-8 and ICD-9:

• 431.01: Nontraumatic subdural haemorrhage with hypertension
• 431.91: Nontraumatic subdural haemorrhage without hypertension
• 4330X: Occlusion and stenosis of vertebral and basilar artery without cerebral infarction
• 4331X: Occlusion and stenosis of carotid artery without cerebral infarction
• 4339X: Occlusion and stenosis of other precerebral artery without cerebral infarction
• 4349X: Occlusion and stenosis of cerebral artery without cerebral infarction

** I69 is accepted only if it is the cause of death.

References

1. Rapola JM, Virtamo J, Korhonen P, Haapakoski J, Hartman AM, Edwards BK, Heinonen OP. Validity of diagnoses of major coronary events in national registers of hospital diagnoses and deaths in Finland. Eur J Epidemiol. 1997;13(2):133-8.
2. Leppala JM, Virtamo J, Heinonen OP. Validation of stroke diagnosis in the National Hospital Discharge Register and the Register of Causes of Death in Finland. Eur J Epidemiol. 1999;15(2):155-60.
3. Pajunen P, Koukkunen H, Ketonen M, Jerkkola T, Immonen-Räihä P, Kärjä-Koskenkari P, Mähönen M, Niemelä M, Kuulasmaa K, Palomäki P, Mustonen J, Lehtonen A, Arstila M, Vuorenmaa T, Lehto S, Miettinen H, Torppa J, Tuomilehto J, Kesäniemi YA, Pyörälä K, Salomaa V. The validity of the Finnish hospital discharge register and causes of death register data on coronary heart disease. Eur J Cardiovasc Prev Rehabil. 2005;12:132-137.
4. Salomaa V, Miettinen H, Kuulasmaa K, Niemela M, Ketonen M, Vuorenmaa T, Lehto S, Palomaki P, Mahonen M, Immonen-Raiha P, Arstila M, Kaarsalo E, Mustaniemi H, Torppa J, Tuomilehto J, Puska P, Pyorala K. Decline of coronary heart disease mortality in Finland during 1983 to 1992: roles of incidence, recurrence, and case-fatality. The FINMONICA MI Register Study. Circulation. 1996;94(12):3130-7.
5. Tuomilehto J, Rastenyte D, Sivenius J, Sarti C, Immonen-Raiha P, Kaarsalo E, Kuulasmaa K, Narva EV, Salomaa V, Salmi K, Torppa J. Ten-year trends in stroke incidence and mortality in the FINMONICA Stroke Study. Stroke. 1996;27(5):825-32.
6. Luepker RV, Apple FS, Christenson RH, Crow RS, Fortmann SP, Goff D, et al. Case Definitions for Acute Coronary Heart Disease in Epidemiology and Clinical Research Studies: A Statement From the AHA Council on Epidemiology and Prevention; AHA Statistics Committee; World Heart Federation Council on Epidemiology and Prevention;. Circulation 2003; 108(20):2543-49. [Circulation free full text]

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