who european childhood obesity surveillance initiative trudy wijnhoven who regional office for...

WHO European Childhood Obesity WHO European Childhood Obesity Surveillance InitiativeSurveillance Initiative

Trudy WijnhovenWHO Regional Office for Europe, Copenhagen

TrainingPorto, Portugal, 13-15 February 2008

Part 1Part 1

Background and objectives of the surveillance system

Introduction to protocol Ethical aspects Confidentiality of the data

Part 2Part 2

Protocol• Review in detail• Questions and answers

Part 3Part 3

Organization of the Country Coordination Team and division of responsibilities

Specific role of examiners Routing of data collection forms Standardization of conditions Support of children with anxieties Prevention of stigmatization and bullying Setting up the measurement session of the children

in a school Interaction with schools, children and parents

PART 1PART 1

Individual growth monitoring & Individual growth monitoring & Nutritional surveillanceNutritional surveillance

Individual growth monitoring• Collection of anthropometric data at the individual level• Asses the need to refer this particular child to improve

growth and health (e.g. nutrition education, breastfeeding support, supplementation, treatment underlying diseases, physical activity education)

• Monitor individual growth pattern over time Surveillance

• Collection of anthropometric data at the population level• Asses the prevalence of both under- and over-nutrition for

purposes of programme planning, implementation and evaluation

• Monitor prevalence trends over time

Nutritional surveillanceNutritional surveillance

Continuous monitoring of the physical status of a population, based on repeated surveys, or on data from child health or growth- monitoring programmes

Information on the prevalence of over- and undernutrition is used to promote, implement and evaluate programmes aimed at improving health and nutritional status

Surveillance ≠ screeningSurveillance ≠ screening

Screening means applying a test to or measuring a defined group of persons in order to identify an early stage, a preliminary stage, a risk factor or a combination of risk factors of a disease – the people who are found are then treated.

A screening system aims to identify a certain disease or risk factor for a disease before the affected person spontaneously seeks treatment, in order to cure the disease or prevent or delay its progression or onset by early intervention.

BackgroundBackground

Overweight in children is an increasing problem in Europe• Associated with risk factors for cardiovascular disease,

diabetes, mental disorders, lower self-esteem• 60% overweight before puberty remain overweight in

early adulthood Prevention is seen as most feasible option 1/3 countries only expand routine growth

monitoring beyond age of 6 years• If countries do individual growth monitoring, often data

are not transferred to a national database

21.4

21.9

21.7

19.5

18.0

14.8

16.6

17.0

15.5

14.8

14.7

16.0

12.6

9.8

4.9

11.7

11.3

9.9

12.3

10.5

7.5

6.9

8.3

6.3

4.4

4.0

3.6

4.2

6.7

11.4

4.4

5.7

20.0

15.2

22.5 7.0

2.0

4.5

3.0

4.0

18.9

7.4

10.3

10.5

6.9

9.1

8.7

15.0

14.0

14.3

12.9

16.0

11.5

15.8

13.3

13.7

16.7

19.9

19.1

5.9

5.4

3.9

2.4

11.2

7.6

4.9

4.0

3.9

3.0

4.1

3.0

5.5

7.0

6.6

4.6

5.8

10.3

10.3

10.1

17.0

40 30 20 10 0 10 20 30 40

Portugal, 2002-2003, 7-9

Spain, 1998-2000, 2-9

Italy: five villages in Milan province, 2000-2002, 6-11

Ireland, 2001-2002, 4-9

United Kingdom: three South Wales localities, 2001-2002, 5

Cyprus, 1999-2000, 6-9

Poland, 2000, 1-9

Germany: Zerbst, Hettstedt and Bitterfeld counties, 1998-1999, 5-10

Sweden, 2003, 8

Iceland, 2004, 9

Switzerland, 2002-2003, 6-9

Norway, 2000, 8-9

France, 2000, 7-9

Sweden, 2003, 4

Slovakia, 2001, 7-9

Italy: Perugia, Terni and Rieti provinces, 1993-2001, 3-9

Greece, 2003, 2-6

Netherlands, 2005, 2-9

Serbia and Montenegro: North Backa region, 1995-2002, 6-10

Cyprus, 2004, 2-6

Germany: Aachen city, 2001-2002, 5-6Su

rvey

cha

ract

eris

tics

: cou

ntry

, yea

r, a

ge r

ange

(y

ears

)

Percentage (%)

Girls Boys

Pre-obese, measured

Obese, measured

Pre-obese, self- or parent-reported

Obese, self- or parent-reported

Overweight, measured

Source: WHO Regional Office for Europe, 2006

Overweight among schoolage children Overweight among schoolage children in the WHO European Regionin the WHO European Region

Limitations to childhood obesity Limitations to childhood obesity surveillance in Europesurveillance in Europe

Only around 25% of Member States have validated national prevalence data on overweight or obesity in children

Measurement tools, calculation and presentation of data are not standardized

Difficult to monitor time trends, make international comparisons and evaluate effectiveness of interventions

Why European childhood obesity Why European childhood obesity surveillance initiative?surveillance initiative?

Key to stimulate adequate political response and policies

Routine data provide most robust information

Monitor progress of achievement of the goals set

What will it be?What will it be?

The childhood obesity surveillance system will be an ongoing, systematic process of collection, analysis, interpretation and dissemination of descriptive information for monitoring excess body weight and for use in programme planning and evaluation.

Country overviewCountry overview

UK, WalesUK, England

Sweden

Spain

Slovenia

Serbia

Portugal

Norway

The NetherlandsMalta Lithuania

Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14

Bosnia & Herzegovina


Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14



Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14


New or integration with existing New or integration with existing surveillance systemssurveillance systems

Although each country is free to develop a system that fits their local circumstances it is imperative that data are collected according to a common agreed protocol and that they contain the stipulated core items.

The system is designed as simple as possible and should not demand a major investment of public resources.

There is no intention to replace existing country’s health, anthropometry and dietary surveillance systems already ongoing or in the planning, on the contrary, the system should if possible be integrated with them.

ProcessProcess

1st Data collectionround

October 2006

October 2005

Brainstorming

1st MS Consultation

Istanbul Conference

1st MeetingSurveillance Initiative

November2006

June2007

December 2007

2nd MeetingSurveillance Initiative

May2008

September2007

ProcessProcess

1st Data collectionround

School year 2007/2008

Spring/Summer 2008

Data reportingPrevalence

Autumn 2008

Data analysis

Summer 2008

Data processing

2nd data collectionround

School year2009/2010 2009/2010 2010 2010

Data reportingPrevalence -Trends


Sweden

Spain

Slovenia

Serbia

Portugal

Norway


Latvia

Italy

Ireland

Hungary

Estonia

The Czech Republic

Cyprus

Bulgaria

Belgium

14


Organization structureOrganization structure

Surveillance Initiative Investigators Team

----------------------------------------WHO/EURO & PIs each country

Country Coordination Team Country Coordination Team Country Coordination Team

Advisory Group

Data clerks Examiners School personnel

Executive Group

PurposePurpose

The system will be aiming to measure routinely (at two-year-intervals) the trends in overweight and obesity in children aged 6.0-9.9 years in order to• have a correct understanding of the progress of the

epidemic in this population in each country• harmonize at the European level and able to make

inter-country comparisons within the WHO European Region

• set the European agenda and report back on trends in 2010 to WHO Regional Committee and EC

Study designStudy design

Semi-longitudinal: each 2 yrs a new cross-sectional sample of the same age group will be drawn.

Optional: longitudinal• To estimate incidence and remission rates of

overweight, which enables identification of target groups for prevention and intervention at local level.

• As children are more likely to become overweight at earlier ages and are more likely to remain overweight as they become older.

Setting and PopulationSetting and Population

Nationally representative sample of primary schools / classes

Sentinel site approach Age groups: 6-, 7-, 8 and/or 9-year-olds Sample size: final effective sample ≈2800

≈124-140 classes (90%-80% response rate)

Why children aged 6-9-year-olds?Why children aged 6-9-year-olds?

They precede puberty and eliminate possible differences between countries that could be attributed to variations in the age of puberty.

At these ages the identification is of value to predict the condition in adulthood.

Prevention effforst towards children before puberty will be important in reducing incidence rates and promoting remission.

At the age of 6 years the adiposity rebound starts;• Onset of 2nd period of rapid growth body fat.

VariablesVariables

Mandatory items• measured weight and height• some school environmental characteristics

Optional items:• waist and hip circumferences• dietary intake patterns• physical activity/inactivity patterns• co-morbidities• family’s socioeconomic characteristics• detailed school environmental characteristics

Examiner’s record form

School return form

Family’s record form

School record form

ImplementationImplementation

In close collaboration with teachers, headmasters and other school personnel

May be done in context of whole school approach to promoting health and well-being

Data collection during 4-8 weeks• Not during first 2 weeks of a new school term

or immediately after a major holiday• Mornings

Ethical considerationsEthical considerations

Parents will be fully informed about all study procedures and their informed consent for the measurements and for data treatment (written in local language) obtained on a voluntary basis prior to the child’s enrolment in the system either through a letter or through a school information meeting.

Prior to the measurement also the child is asked whether s/he agrees with it.

Ethical considerationsEthical considerations

Parents have a right to know their child’s body height and body weight measures. Although these will not be given routinely they will be given if requested.

Children will never be told the measures of other children.

The children’s names will not be included in the electronic data files.

It is vital that examiners work in such a way that stigmatization and bullying are minimized and that they will acknowledge the children’s and parents’ right to withhold consent.

Data confidentialityData confidentiality

Confidentiality of all collected and archived data will be ensured.

Identification numbers to the children will be assigned and each register will only mention those numbers.

Only one person in the school/project will have a full list of ID numbers and corresponding names and addresses of the children sampled.

No information of the subjects will be given to outside people.

Forms will be stored in safe cabinets at the national coordinating centre.

END PART 1END PART 1

Thursday 14 February 2008Thursday 14 February 2008ScheduleSchedule

Part 3 Review forms and administration guidance Instruction in taking the interviewing, recording

answers and checking out forms Instruction in taking the anthropometric

measurements and recording the measures Instruction in calibrating the instruments Instruction in instrument maintenance, storage and

transportation

PART 3PART 3

Country coordination teamCountry coordination team

Principal investigator (PI); responsible for the overall coordination and s/he will be a member of the Surveillance Initiative Investigators Team.

Supervisor(s); responsible for the data collection in each sampled school.

Data manager; responsible for the overall data management.

Country teamCountry team

Examiners; responsible for the administration of the examiner’s record form and taking the anthropometric measurements.

Data clerks; responsible for the data entry into electronic data files.

School personnel responsible for the completion of the school return forms and other relevant possible tasks.

Role of examinersRole of examiners

Administration of examiner’s record form. Takes anthropometric measurements. Takes care of instruments and its calibration. Organizes measurement setting in schools. Gives instructions to teachers where needed. Assists school director or teacher in completing the

school return form. Makes sure that data manager receives the

examiner’s record and school return form.

Role of supervisorsRole of supervisors

Tracking examiner’s progress. Ensuring data collection forms are completed

correctly. Keeping data collection to the specified

timeframe. Handling any issues examiners are

encountering. First contact with schools.

Data flow chartData flow chartmandatory formsmandatory forms

Data collection in primary schools, manual checking of forms

Completion of school return forms

Forms sent to national coordinating centre where they will be archived

Data entry carried out twice

Examiners

School personnel

Data manager national coordinating centre

Data manager national coordinating centre

Data cleaning, validation and back-up

Data clerks

Pooled dataset analysisSurveillance Initiative

Investigators Team

Standardization of conditionsStandardization of conditionsExaminersExaminers

Prior to each data collection round, all examiners should be trained and standardized in taking the measurements as accurately and precisely as possible according to the outlined measurement techniques and examiners’ instructions.

Examiners should ensure the basic principles of confidentiality, privacy and objectivity throughout the process.

Examiners should not mention the words “childhood obesity” or give any indication that this data collection refers to the assessment of the prevalence of overweight and obesity in school children.

Examiners should not calculate the child’s BMI values at the point of measurement.

Children have a right to know their body height and body weight measures. Although examiners should not give them routinely they should be given if requested.

Standardization of conditionsStandardization of conditionsChildrenChildren

Children should wear normal, light, indoor clothing without shoes/socks.

Prior to the measurements, they should be asked to take off her/his shoes and socks as well as all heavy clothing (coats, sweaters, jackets, etc). They should also be asked to remove wallets, cellular phones, key chains, belts or any other objects. Further any hair ornaments or braids should be undone.

Children should be asked to go to the toilet just before the measurements.

Children should never be told the measurements of other children.

Standardization of conditionsStandardization of conditionsInstrumentsInstruments

The same anthropometric measuring instruments should be used across a country.

The weighing scale and the stadiometer should be checked and/or calibrated frequently, ideally on each of the days that measurements are taken place and should then be done early morning beforehand.

The instruments need to be highly accurate and precise.

Standardization of conditionsStandardization of conditionsFormsForms

All original data collection forms and administration instructions will be prepared in English and should be translated to local languages and back-translated to English.

The translated forms should be carefully checked for discrepancies with the original English version.

The re-translation should be carried out independently from the initial translation from English to the country, preferable by a professional translator.

Any of the translated data collection forms and administration instructions should not give an indication that this data collection refers to the assessment of the prevalence of overweight and obesity in school children.

Standardization of conditionsStandardization of conditionsTimeTime

The anthropometric measurements should• be carried out over as short a period as possible,

preferable within four weeks and no longer than eight weeks;

• not take place during the first two weeks of a new school term or immediately after a major holiday;

• be done in the mornings before lunch time.

Standardization of conditionsStandardization of conditionsLocationLocation

The children should be measured in a private room.

The children should not be measured in front of their class mates.

Boys and girls will be measured separately.

Support of children with anxietiesSupport of children with anxieties

Explain that the objectives of the project: e.g. The information that will collected will be used to develop better health programmes for them.

Explain how you are going to take the measurements.

Take weight measurement first: easiest to gain co-operation.

Children should never be forced to take part.

Prevention of stigmatization and Prevention of stigmatization and bullyingbullying

Children can be very sensitive about their own size and those of children around them. Measuring body height and body weight could accentuate these sensitivities and increase the risk of stigmatization and bullying. Examiners should handle the process of measuring in such a way as to minimize any potential for harm

Prevention of stigmatization and Prevention of stigmatization and bullyingbullying

Individual results will not be given to any of the school staff.

BMI will not be calculated at the point of measurement.

Children’s privacy and dignity should be respected at all times.

The height and weight displays on the measurement equipment should not be visible to anyone apart from the person recording measurements.

Setting up measurement session in the Setting up measurement session in the schools: prior to the day of measurementsschools: prior to the day of measurements

Contact schools to arrange a convenient time to go into schools to undertake the measurements.

Liaise with schools to send out the informed consent letter to parents.

Follow up with the schools to check that the letters have been sent out and followed prior to the day of the measurements.

A school information meeting for parents and teachers involved may be organized.

A separate note to instruct parents about the clothes a child should wear on the day of the measurements.

Setting up measurement session in the Setting up measurement session in the schools: prior to the day of measurementsschools: prior to the day of measurements

With the school’s help, locate a private setting to do the measurements. In the exceptional case that a separate room is not available, a screened off area of the classroom can be used. Other pupils in the class must not be able to see or overhear the measurement taking place.

Contact the school a few days before the day that you are visiting to confirm that the weighing and measuring will be taking place and that a separate room will be available for you to use.

Setting up measurement session in the Setting up measurement session in the schools: on day of measurementsschools: on day of measurements

Obtain from the school a list with all the registered children of the sampled class, according with their names, birth dates and residential codes.

Explain the teacher/school director what is expected from him/her.

Provide the school return form and let them complete it after the measurement session. You may need to assist them.

Check the completed form and take it back with you.

Setting up measurement session in the Setting up measurement session in the schools: on day of measurementsschools: on day of measurements

Ensure the height measure is correctly assembled and placed on a firm level surface.

Ensure that weighing scales are placed on a firm level surface with the read out display concealed from the participating child and others.

Explain the measurements to the children plenary. Measurement could be part of a physical education

lesson. Ask the children to go to the toilet before the

measurements.

Interaction with schools, children and Interaction with schools, children and parentsparents

1. What should I do if a parent withdraws their child from the measurement process but the child wishes to participate?

2. What should I do if a parent is happy for their child to participate in the surveillance system but the child wishes to opt out?

3. What should I do if a child or parent specifically requests their height and weight data?

4. Will the results be published by school?5. Should children with special needs be weighed and

measured?6. Why are postcode or residential code being collected?


1. What should I do if a parent withdraws their child from the measurement process but the child wishes to participate?

In view of the age of the children involved surveillance system, you should respect the parent’s wishes, and sensitively explain to the child that their parent or carer has asked for them not to take part.


2. What should I do if a parent is happy for their child to participate in the surveillance system but the child wishes to opt out?

Children’s anxieties about being weighed and measured should be addressed sensitively, and children should be encouraged to take part. However, you should respect the child’s wishes and under no circumstances should an unwilling child be made to participate.


3. What should I do if a child or parent specifically requests their height and weight data?

If a parent or child requests the information, the examiner should provide height and weight data confidentially to the parent.

Only raw height and weight data should be provided to parents, and BMI should not be calculated.


4. Will the results be published by school?

No, school league tables will not be published.


5. Should children with special needs be weighed and measured?

Only children who are able to stand on weighing scales and height measures unaided should be weighed and measured .


6. Why are postcode or residential code being collected?

Postcode is collected to enable richer analysis of trends in obesity by allowing analysis by deprivation. Postcode is not used to identify individual children, and safeguards will be placed to protect against this.

END PART 3END PART 3

MEASUREMENTSMEASUREMENTS

AccuracyAccuracy

An examiner is accurate if, on average, he or she measures real size (with an accurate instrument).

He or she is inaccurate (biased) if he or she has a tendency to record values that are higher (positively biased) or lower (negatively biased) than real size.

AccuracyAccuracy

Lack of accuracy (bias) can be assessed in a test-retest study in which several children are measured by the expert and by the examiner.

Bias is calculated as the average difference between the expert and examiner values.

PrecisionPrecision

An examiner is precise if, when re-measuring the same child (within an interval during which the child has not grown and the instrument not de-calibrated), he or she records values that tend to be close to each other and not widely dispersed.

This is independent of whether their average is close to real size or not and thus independent of accuracy.

PrecisionPrecision

Examiner precision is assessed in a test-retest study in which a series of subjects is measured twice by the examiner, after which the differences between pairs of measurements are analysed.

With perfect precision, the second measurement will always give the same value as the first.

ExampleExample

Examiner Measurement Precision Accuracy (estimate of the mean)

1 2 mean

Expert 110 110 110 precise unbiased

1 108 112 110 imprecise unbiased

2 108 108 108 precise negatively biased

3 112 112 112 precise positively biased

who european childhood obesity surveillance initiative trudy wijnhoven who regional office for...

Documents

data slide

time slide

nutritional status slide

national database slide

national prevalence

routine growth monitoring

presentation of data

schoolage children