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A Secondary Analysis of the Cross-Sectional Data Available in the ‘Welsh Health Survey for Children’ to Identify Risk Factors Associated with Childhood Obesity in Wales.

Presented by :Claire BeynonSupervisor :Professor David Fone, Cardiff University

Claire Beynon

Why is childhood obesity a problem?• Prevalence of childhood obesity in Wales 12%.• Impacts on both quality and quantity of life.• Immediate effects:

low self esteem; bullying; depression; type II diabetes.

• Long term effects:Premature mortality; adult morbidity.

• Obesity costs £73 million per annum in Wales.

Claire Beynon

Why is childhood obesity a problem?

Lobstein and Jackson Leach in Foresight Report, UK Government Office for Science, 2007.

Claire Beynon

The Data Choice in the UK

• Childhood Measurement Programme• Millennium Cohort Study• Welsh Health Survey• English Health Survey• Collecting new data

Claire Beynon

Welsh Health Survey

• Adult Survey• Children's Survey• Geography• Question development• Sampling frame• Sampling technique• Response rate

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Research Question• What are the important risk factors for childhood

obesity for children aged 4 to 15 years in Wales?

Research Objectives• Identify and quantify cross-sectional associations

between obesity in children in Wales aged 4-15 years and the risk factors available in the Welsh Health Survey.

• Make recommendations for policy where appropriate.

Claire Beynon

1032 records excluded on basis of non-English; not relevant; not in age range;

incorrect outcome; data not collected in WHS

1086 titles and abstracts screened using inclusion criteria

41 full-text articles excluded on basis of non-English; not relevant; not in age range; incorrect outcome; data not

collected in WHS

13 articles included in review of the literature

54 full-text articles assessed for eligibility using inclusion criteria

Total of 1086 records identified using ‘Childhood Obesity’ and

‘Risk Factors’ from four electronic databases

754 records identified through EMBASE electronic

database

281 records identified through MEDLINE

electronic database

41 records identified through PSYCHINFO electronic database

10 records identified through Cochrane

Library

Literature review

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Study Design

• Secondary Analysis of Data from the WHS.

• Dataset included n=11,279 children (aged 4-15 years) between 2008 and 2011.

• Descriptive statistics, and logistic regression.

Claire Beynon

Risk Factors• Socio-demographic/socioeconomic variables:

Sex, age, National Statistics Social Classification (NSSEC), housing tenure and Welsh Index of Multiple Deprivation (WIMD).

• Lifestyle variables: Unhealthy food consumption; sugar sweetened beverages; physical activity (PA) levels

• Illness: Currently treated illnesses.

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Results

Year of Survey

No response to BMI (%)

Normal Weight Number (%)

Over Weight

Number (%)

Obese Number (%)

TOTAL Number (%)

2008 661 (32.9%) 878 (43.7%) 234 (11.6%) 238 (11.8%) 2,011 (100%) 2009 652 (27.2%) 1,127 (46.9%) 282 (11.8%) 337 (14.1%) 2,398 (100%) 2010 583 (25.3%) 1,086 (47.1%) 286 (12.4%) 351 (15.2%) 2,306 (100%) 2011 609 (25.6%) 1,144 (48.1%) 281 (11.8%) 345 (14.5%) 2,379 (100%) 2012 696 (31.9%) 951 (43.5%) 227 (10.4%) 311 (14.2%) 2,185 (100%) TOTAL 3,201 (28.4%) 5,186 (46.0%) 1,310 (11.6%) 1,582(14.0%) 11,279 (100%)

Body Mass Index classifications for children by year of WHS

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ResultsBody Mass Index classifications for children’s age group

Age Group No response to BMI

Normal Weight

Number (%)

Over Weight

Number (%)

Obese Number (%)

TOTAL Number (%)

4-6 638 (23.1%) 1,460 (53.0%) 345 (12.5%) 314 (11.4%) 2,757 (100%) 7-9 658 (24.7%) 1,320 (49.6%) 294 (11.0%) 392 (14.7%) 2,664 (100%) 10-12 818 (29.2%) 1,188 (42.3%) 347 (12.4%) 453 (16.1%) 2,806 (100%) 13-15 1,087 (35.6%) 1,218 (39.9%) 324 (10.6%) 423 (13.9%) 3,052 (100%) TOTAL 3,201 (28.4%) 5,186 (46.0%) 1,310 (11.6%) 1,582 (14.0%) 11,279 (100%)

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Odds RatiosHow to calculate:OR = Odds of exposure in cases

Odds of exposure in control

How to interpret: • OR>1 increased risk• OR=1 no difference• OR<1 decreased risk• Confidence intervals, if they cross 1 not significant

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Results

Risk Factor Odds Ratio 95% CI P value

Sex Male Reference

Female 0.79 0.70 to 0.89 p<0.001*

Age 4-6 Reference

7-9 1.42 1.19 to 1.70 p<0.001*

10-12 1.65 1.39 to 1.97 p<0.001*

13-15 1.44 1.20 to 1.73 p<0.001*

Significant association between childhood obesity and the following factors denoted with *

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ResultsRisk Factor OR 95% CI P value

NSSEC 3 Professional/ Managerial Reference

Intermediate 1.17 0.98 to 1.38 0.08

Routine/ Manual 1.32 1.14 to 1.54 p<0.001*

WIMD Lowest Reference

Low 1.08 1.19 to 1.70 p=0.44

Mid 1.23 1.01 to 1.50 p=0.04*

High 1.33 1.09 to 1.62 p=0.005*

Highest 1.23 0.99 to 1.53 p=0.06

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ResultsRisk Factor OR 95% CI P value

Illness No illness Reference

One illness 1.20 1.05 to 1.38 p=0.008*

Two or more illnesses 1.50 1.22 to 1.85 p<0.001*

Physical Activity

Meets recommendation Reference

Does not meet recommendation

1.33 1.17 to 1.52 p<0.001*

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Results

Risk Factor OR 95% CI P value

Fruit & Vegetables Not daily Reference

Both daily 0.96 0. 85 to 1.09 p=0.82

Sugar sweetened beverages

Not daily Reference

Daily 1.02 0.83 to 1.27 p=0.82

Crisps, chips or sweets Not daily Reference

Daily 0.89 0.79 to 1.01 p=0.08

No significant association between childhood obesity and the following factors:

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Differences from CMP data

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Strengths of the study

• WHS uses stratified random sampling.• Results for 3000 children achieved per annum.• Good response rate at 75%.• Known confounding accounted for by use of multivariable

analysis.• Provides new insights into existing data.• Information from Wales on which to base Welsh policy.

Claire Beynon

Limitations of the study

• Risk of bias, e.g. recall bias; reporting of food consumption and physical activity reporting. Non response bias.

• Reverse causality possible due to study design.• Selection bias, private homes surveyed (not

institutions).• Unknown confounding possible (not all risk factors

measured).• Interactions not explored.

Claire Beynon

Conclusions• Some risk factors associated with childhood obesity

are not modifiable (e.g. sex and age of the child). • Some risk factors are not easily modifiable in the short

term, e.g. the circumstances of the family (NS-SEC classification of the parent and housing tenure).

• Two findings are potentially more easily modifiable:

– the association between childhood obesity and not meeting the PA recommendations

– the NHS response to the care planning of children with a long term condition.

Claire Beynon

Recommendations• Increase physical activity in schools to an hour a day,

so all children have levels of PA that protect them from obesity without increasing inequalities in health.

• Utilise the CMP feedback to provide advice on relevant physical activity options that are affordable and accessible e.g. green spaces; walks; free swimming.

• Ensure all children with a long term condition get help to avoid or manage obesity through an holistic care package.