WWW-publications from the WHO MONICA Project
June 1999
Vivan Lundberg1, Hanna Tolonen2 and Kari Kuulasmaa2 for the WHO MONICA Project3
1 Department of Internal Medicine, Kalix Hospital, Sweden
2 MONICA Data Centre, National Public Health Institute, Helsinki, Finland
3 Annex: Sites and key personnel of the WHO MONICA
Project
Thanks are due to Alun Evans and Annette Dobson who commented on the text.
The MONICA Centres are funded predominantly by regional and national governments, research councils, and research charities. Coordination is the responsibility of the World Health Organization (WHO), assisted by local fund raising for congresses and workshops. WHO also supports the MONICA Data Centre (MDC) in Helsinki. Not covered by this general description is the ongoing generous support of the MDC by the National Public Health Institute of Finland, and a contribution to WHO from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA for support of the MDC. The completion of the MONICA Project is generously assisted through a Concerted Action Grant from the European Community. Likewise appreciated are grants from ASTRA Hässle AB, Sweden, Hoechst AG, Germany, Hoffmann-La Roche AG, Switzerland, the Institute de Recherches Internationales Servier (IRIS), France, and Merck & Co. Inc., New Jersey, USA, to support data analysis and preparation of publications.
In the WHO MONICA Project (1), three independent cross-sectional population surveys were carried out in a large number of populations in the 1980s and early 1990s to measure the classical risk factors for cardiovascular diseases. Specific questions for women were introduced in the November 1990 version of the MONICA Manual (2). Since most of the MONICA Collaborating Centres (MCCs) had already started and many had even finished their middle population surveys by that time, these new questions were considered optional measurements in that survey. As a result, less than half of the MCCs had these questions in their middle surveys. In the final survey, the questions were asked in most of the MCCs.
The MONICA Project has a standard format for data transfer to the MONICA Data Centre (MDC). To facilitate this it is necessary to collect the information in such a format that the data required for the data transfer can be extracted. The four questions for women in the MONICA Manual (2) are:
MENOP "Are you still having monthly periods?"
1 = yes, as usual
2 = yes, but irregularly
3 = no
8 = not relevant (men and known pregnant women)
9 = insufficient dataAGEM "How old were you when your periods stopped completely?
88 = not relevant (MENOP = 1, 2 or 8)
99 = insufficient dataHORM "Are you taking (in the last month) sex hormones (estrogens) for menopausal symptoms?"
1 = yes
2 = no
8 = not relevant (MENOP = 1 or 8)
9 = insufficient dataPILL "Are you taking (in the last two months) contraceptive pills or injections?"
1 = yes
2 = no
8 = not relevant (MENOP = 3 or 8)
9 = insufficient data
Some MCCs had already before included similar questions, but with a different wording, which could lead to discrepancies and difficulties in interpretation.
The main purposes of this quality assessment report are:
The results of this document are reported by Reporting Unit Aggregates (RUAs) which are foreseen as potential candidates for units of analysis of the MONICA data. The RUAs are identified by an abbreviation and a version letter. The RUAs, their abbreviations and Reporting Units as well as the number of subjects in the surveys are listed in Table 1. Altogether 40 RUAs are considered for the middle survey and 39 for the final.
The originals in the local language and/or the English translations of the survey questionnaires used in the surveys were available in the MDC for all RUAs (Table 2). In 1991 a questionnaire on the MONICA Population Survey Procedures (Form VI), including a question on whether the questionnaire was self-administered or completed during an interview, was sent to all MCCs. The questionnaire was completed again in 1995 in relation to the final survey.
The survey data on the items for women were transferred to the MDC using the MONICA core data transfer format (Form 04, versions 6 and 7) (2). The items on women in the data transfer format remained unchanged throughout the middle and final surveys.
For the quality analyses only data for women are used. All observations within the age group 25-64 are included, except in FRA-LIL in the final survey and in AUS-NEW, FRA-STR, FRA-TOU, LTU-KAU, POL-TAR, POL-WAR, RUS-MOC, RUS-MOI, and SWI-TIC where the age range studied was 35-64. Age was defined as age in full years on the date of examination (see DEF1 in reference 3). No weighting was applied to the data.
Findings
Table 3 shows a comparison of the MONICA standard question on MENOP and questions actually used in the RUAs. In the data transfer format the question was "Are you still having monthly periods?".
In the middle survey 11 out of 40 RUAs used question identical to the MONICA format, 23 RUAs did not include the question at all. Remaining 6 RUAs had included the question, but incorrectly phrased, or without all required alternatives:
In the final survey 27 out of 39 RUAs used a question identical to the standard MONICA format, 5 RUAs did not include the question at all. In the remaining 7 RUAs the question was incorrectly formulated or the alternatives did not accord with the MONICA standard:
Discussion
In the middle survey the question was worded differently in DEN-GLO and USA-STA, which may cause problems in interpreting the alternatives. In AUS-NEW, GER-BRE, and POL-TAR the question was worded differently, but the meaning is the same. AUS-NEW, DEN-GLO, GER-BRE, and USA-STA had only the alternatives "yes" and "no" which makes it difficult to classify pregnant women and women with regular or irregular menstruation. POL-TAR omitted the alternative "not relevant".
In the final survey AUS-PER and USA-STA worded the question differently from the MONICA standard and the alternatives therefore will have a different meaning. CAN-HAL, DEN-GLO, GER-BRE, NEZ-AUC, and USA-STA had only alternatives "yes" and "no" (alternatives "yes, but irregularly", "not relevant" and "insufficient data" missing). In LTU-KAU the alternative "not relevant" was missing.
Findings
Table 3 shows a comparison of the MONICA standard question on AGEM and those used in the RUAs. In the data transfer format the question was "How old were you when your periods stopped completely?".
In the middle survey 11 out of 40 RUAs used a question identical to the standard MONICA format, 26 RUAs did not include the question at all. In the remaining 3 RUAs the question was incorrectly formulated or the alternatives did not accord with the MONICA standard:
In the final survey 29 out of 39 RUAs used a question identical to the standard MONICA format, 7 RUAs did not include the question at all. In the remaining 3 RUAs the question was incorrectly formulated or the alternatives did not accord with the MONICA standard:
In many RUAs the alternative "not relevant" was extracted from the MENOP question.
Discussion
In the middle survey in ITA-BRI age of complete stopping of menstrual periods can be calculated from the date of birth, but it is not known what the alternatives were used for pregnant women and women still menstruating. In UNK-BEL the age of complete stopping of menstrual periods can be calculated from the date of last periods.
Most RUAs had the "not relevant" alternative documented in the MENOP question or as a separate question. The "insufficient data" alternative can be inferred from those who did not reply to the question.
In the final survey in AUS-PER and NEZ-AUC the question was worded differently, but the meaning is the same and the questions should be accepted.
In AUS-PER, NEZ-AUC and UNK-GLA the alternative "not relevant" was missing. Most RUAs had the "not relevant" alternative documented in the MENOP question or as a separate question. The "insufficient data" alternative can be collected from those, who did not reply to the question.
Findings
Table 3 shows a comparison of the MONICA standard question on HORM and those used in the RUAs. In the data transfer format the question was "Are you taking (in the last month) sex hormones (estrogens) for menopausal problems?".
In the middle survey 3 out of 40 RUAs used a question identical to the standard MONICA format, 31 RUAs did not include the question at all. In the remaining 6 RUAs the question was incorrectly formulated or the alternatives did not accord with the MONICA standard:
In the final survey 21 out of 39 RUAs used a question identical to the standard MONICA format, 7 RUAs did not include the question at all. In the remaining 11 RUAs the question was incorrectly formulated or the alternatives did not accord with the MONICA standard:
Discussion
In the middle survey the question did not stress hormonal use in the last month in ITA-BRI, UNK-BEL and UNK-GLA. The question should still be accepted as women usually used hormones for long periods, and those on hormones now have probably used them for the last month. The DEN-GLO question is difficult to fit into the MONICA format as it merely indicates if the woman has ever been on hormone treatment.
In the final survey CAN-HAL, UNK-GLA asked if the women were using hormones now. This can be accepted as women on hormones now most likely had been using them for the last month. AUS-PER asked if the women had ever used hormones. This cannot be accepted, as the women may have not been using hormones for the last month. NEZ-AUC asked if the women had used hormones for the last 12 months, which also cannot be accepted as it does not reveal if the women have been using hormones in the last month.
RUAs which do not have the alternative "not relevant" can derive it from MENOP. The alternative "insufficient data" can be taken from respondents who have not replied to the question on HORM.
Findings
Table 3 shows a comparison of the MONICA standard question on PILL and those used in the RUAs. In the data transfer format the question was "Are you taking (in the last 2 months) contraceptive pills or injections?".
In the middle survey 3 out of 40 RUAs used a question identical to the standard MONICA format, 23 RUAs did not include the question at all. In the remaining 14 RUAs the question was incorrectly formulated or the alternatives did not accord with the MONICA standard:
In the final survey 20 out of 39 RUAs used a question identical to the standard MONICA format, 6 RUAs did not include the question at all. In the remaining 13 RUAs the question was incorrectly formulated or the alternatives did not accord with the MONICA standard.
Discussion
In the middle survey AUS-NEW, AUS-PER, ITA-FRI, UNK-BEL and UNK-GLA have asked about current oral contraceptive use. This could be accepted as most women on the pill will have been on them longer than two months. DEN-GLO asked if the women had ever taken oral contraceptives. This would be difficult to fit into the MONICA model as it does not tell if they are using the pill in the last month. GER-BER, GER-COT, GER-EGE, GER-ERF, GER-HAC, GER-KMS asked if the woman had been using oral contraceptives in the last 6 weeks. This could be accepted, as few women probably started using the pill between 6 weeks and 2 months age. Centres who are missing the "not relevant" alternative can derive it from MENOP. The alternative "insufficient data" can be taken from participants, who have not replied to the question on PILL.
In the final survey AUS-PER, CAN-HAL, FIN-KUO, FIN-NKA, FIN-TUL, GER-BRE, ITA-BRI, NEZ-AUC and UNK-GLA have asked if the women are on the oral contraceptives now. This might be accepted, as women usually are on the pill for a long period of time, and most women who are using the pill now, probably have used them for the last 2 months. In GER-BRE no alternatives were given. Centres who are missing the alternative "not relevant" can derive it from MENOP. The alternative "insufficient data" can be taken from participants, who have not answered the question.
When the survey core data were received in MDC, the data were checked routinely for the following constraints:
All violations of these constraints were reported to the MCCs for their correction or elucidation. Data values outside the limits were acceptable by the MDC once the MCC had checked the values and vouched for their correctness. If this assurance was not forthcoming, MCCs were asked to supply the correct values. The MCCs were asked to correct values only if they were incorrect. The current unresolved constraint violations are shown in Appendix 1.
There are only a few unresolved constraint violations in the middle surveys, for BEL-CHA, GER-BER, GER-COT, GER-HAC, GER-KMS and UNK-BEL and none in the final survey.
Table 4 presents the availability of data on MENOP in each RUA, in the middle and final survey. The availability is summarized in Table A.:
| No data | < 50% | 50% - 90% | > 90% | Number of RUAs | |
|---|---|---|---|---|---|
| Middle | 23 | 1 | 3 | 13 | 40 |
| Final | 7 | 0 | 0 | 32 | 39 |
Table 5 presents the distribution of MENOP. In the middle survey only 6 and in the final survey 21 RUAs have MENOP coded in the standard MONICA way. In most cases either ‘Yes, but irregular’ or ‘Not relevant’ is missing or both.
In 15 RUAs the question was not asked in the middle survey but was asked in the final survey. In DEN-GLO and SWE-GOT data are available for the middle survey but not for the final survey. In AUS-PER in the middle survey only 3% had some information on MENOP and all those were coded as "Not relevant"; In the final survey 100% had information on MENOP.
In BEL-CHA and BEL-GHE in the middle survey there is 45% and 30% missing data, respectively.
In the middle survey in AUS-NEW, AUS-PER, POL-TAR and POL-WAR there is 0% for "Not relevant" (pregnant) even though there is a question relating to the pregnancy in the local questionnaire.
In the final survey in FRA-LIL, FRA-STR, FRA-TOU, ITA-FRI, SWI-TIC there is 0% for "Not relevant" (pregnant) even though there is a question relating to the pregnancy in the local questionnaire.
In the middle survey in AUS-PER, BEL-CHA, and BEL-GHE there is no question related to menopausal status in the local questionnaire but the MDC has data for item MENOP. In GER-EGE, and GER-ERF there is question about menopausal status in the local questionnaire but the MDC does not have data for item MENOP.
In the final survey in RUS-NOC there is no question related to menopausal status in the local questionnaire but the MDC has data for the item MENOP. In DEN-GLO, NEZ-AUC, and SWE-GOT there is a question about menopausal status in the questionnaire but the MDC does not have any data for the item MENOP.
Table 4 presents the availability of data on AGEM in each RUA in the middle and final surveys. The availability is summarized in Table B.:
| No data | < 50% | 50% - 90% | > 90% | Number of RUAs | |
|---|---|---|---|---|---|
| Middle | 27 | 2 | 4 | 7 | 40 |
| Final | 8 | 1 | 2 | 28 | 39 |
In 7 RUAs data are available for both the middle and final survey. In 6 RUAs there are no data for the middle or final survey. In 19 RUAs where there are no data for the middle survey, data are available for the final survey.
In the middle survey in BEL-CHA and BEL-GHE there is no question related to the age when periods stopped in the local questionnaire but the MDC has data for the item AGEM. In GER-EGE, GER-ERF, ITA-BRI and POL-WAR there is a question about the age when periods stopped but MDC does not have any data for the item AGEM.
In DEN-GLO and SWE-GOT data were available for middle survey but not for the final survey. In the final survey in DEN-GLO and SWE-GOT there is a question about the age when periods stopped but MDC does not have any data for the item AGEM.
Table 4 presents the availability of data on HORM in each RUA in the middle and final survey. The availability is summarized in Table C.:
| No data | < 50% | 50% - 90% | > 90% | Number of RUAs | |
|---|---|---|---|---|---|
| Middle | 31 | 1 | 1 | 7 | 40 |
| Final | 9 | 0 | 3 | 27 | 39 |
In 8 RUAs data are available for both the middle and final survey. In 7 RUAs there are no data for the middle nor final survey. In 18 RUAs where there are no data for the middle survey, data are available for the final survey.
Table 6 presents the distribution of HORM. In the middle survey there were 31 RUAs with 100% insufficient data, in the final survey 8 RUAs. In 4 RUAs in the middle survey and in 28 in the final survey data for HORM are coded according to the standard MONICA format.
CHN-BEI and RUS-MOI in the final survey have coded the HORM correctly, but for alternative "yes", there are no observations. It seems unlikely that no one is using hormones.
In the middle survey in AUS-PER and USA-STA there is no question relating to the use of hormone replacement therapy but the MDC has data for the item HORM. In DEN-GLO, and ITA-BRI there is a question about the use of hormone replacement therapy but MDC does not have any data for the item HORM.
In the final survey in USA-STA there is no question relating to the use of hormone replacement therapy but the MDC has data for the item HORM. In DEN-GLO, NEZ-AUC, and SWE-GOT there is a question about hormone replacement therapy but the MDC does not have any data for the item HORM.
Table 4 presents the availability of data on PILL in each RUA in the middle and final survey. The availability is summarized in Table D.:
| No data | < 50% | 50% - 90% | > 90% | Number of RUAs | |
|---|---|---|---|---|---|
| Middle | 24 | 0 | 1 | 15 | 40 |
| Final | 10 | 1 | 1 | 27 | 39 |
In 10 RUAs data are available for both the middle and final surveys. In 8 RUAs there are no data for the middle or final surveys. In 14 RUAs where there are no data for the middle survey, data are available for the final survey.
Table 7 presents the distribution of PILL. In 12 RUAs in the middle survey and in 27 in the final survey data for PILL are coded according to standard MONICA format. In the middle survey there are 24 RUAs with 100% insufficient data, and in the final survey 9.
POL-TAR middle and final survey the proportion of the alternative "yes" is zero, even though they are coded correctly otherwise. MCC has confirmed that the result is correct.
In the middle survey in USA-STA there is no question related to the use of oral contraceptives in the local questionnaire but the MDC has data for the item PILL. In DEN-GLO and ITA-BRI there is a question about the use of oral contraceptives but the MDC does not have any data for the item PILL.
In the final survey in USA-STA there is no question related to the use of oral contraceptives in the local questionnaire but the MDC has data for the item PILL. In DEN-GLO, FIN-KUO, FIN-NKA, FIN-TUL and SWE-GOT there is a question about the use of oral contraceptives but the MDC does not have any data for the item PILL.
Tables 8, 9 and 10 give the overall scores for the quality of data for the items MENOP, HORM and PILL in each RUA. The scores were defined as follows:
a) Questionnaire compliance score:
| Score = | 0 | if no questionnaire available at the MDC, no MENOP/HORM/PILL question in the questionnaire, or the formulation of the question is significantly different from the standard format; |
| 1 | if an alternative formulation of the question was used, but it is considered to have only minor or no effect on prevalence estimates; | |
| 2 | for all other RUAs. |
b) Insufficient data score:
| Score = | 0 | if proportion of "insufficient" > 10%; |
| 1 | if proportion of "insufficient" is 5-10%; | |
| 2 | for all other RUAs. |
c) Summary score:
| Score = | 2 | if the sum of Questionnaire compliance score and Insufficient data score is 3 or 4; |
| 1 | if the Questionnaire compliance score and Insufficient data score both are 1; | |
| 0 | if the Questionnaire compliance score or Insufficient data score is 0. |
Even though it is unlikely that the data on MENOP, HORM or PILL will be used for 5-year trend analysis, the trend score is introduced.
d) Trend score:
| Score = | 2 | if the sum of Summary score for middle and final survey is 3 or 4; |
| 1 | if Summary score for middle and final survey is 1; | |
| 0 | if Summary score for middle or final survey is missing or 0. |
The questions for women only were not included from the beginning of the MONICA Project, and therefore are absent from the initial survey. A number of RUAs had included such questions in the initial survey, but they were often worded differently from the MONICA questions. The women's questions were introduced at a time when most MCCs had already completed their middle survey, but had not yet transferred the data to the MDC. If the MCCs had collected data on the women's questions, they had a chance to transfer them to the MSC. It is, however, understandable that the details of the local questions differed from the MONICA standard questions. In the final survey the use of the women's questions by all MCCs was highly recommended. Most MCCs used them, but many changed the wording of the question MENOP to correspond to the MONICA standard, leaving the questions AGEM, HORM, and PILL unchanged.
Although the data on the women's questions are sparse in the middle surveys, their availability and quality are reasonably good in the final surveys.
The following list includes only RUAs with specific findings or exceptional background information relevant for the use of data, and the RUAs for which additional clarification is expected.
AUS-NEW
AUS-PER
BEL-CHA and BEL-GHE
CAN-HAL
CHN-BEI
CZE-CZE
DEN-GLO
FIN-KUO, FIN-NKA and FIN-TUL
FRA-LIL
FRA-STR
FRA-TOU
GER-AUR and GER-AUU
GER-BER
GER-BRE
GER-COT
GER-EGE
GER-ERF
GER-HAC
GER-KMS
HUN-BUD
HUN-PEC
ICE-ICE
ITA-BRI
ITA-FRI
LTU-KAU
NEZ-AUC
POL-TAR
POL-WAR
RUS-MOC
RUS-MOI
RUS-NOC
RUS-NOI
SWE-GOT
SWE-NSW
SWI-TIC
SWI-VAF
UNK-BEL
UNK-GLA
USA-STA
YUG-NOS