Prevalence of obesity and associated risk factors in chinese pre school children aged 6 to 72 months old in singapore 2

2 To compare the variation of overweight and obesity by age groups 3 To evaluate the associations between overweight/obesity with potential risk factors such as birth weight, duration of

(2) To compare the variation of overweight and obesity by age groups

(3) To evaluate the associations between overweight/obesity with potential risk factors such as birth weight, duration of preschool hours per day, physical activities (playing outdoors, leisure activities), sedentary activities (watching television, playing computer/television/hand held video games, reading, drawing and coloring activities), socioeconomic status (father’s education, mother’s education, total combined monthly income), presence of park or garden near to home, breastfeeding, types of breastfeeding, maternal smoking and alcohol consumption during pregnancy

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2.1.3 Hypothesis for Risk Factors

From the literature review, we hypothesized that overweight, obesity or combined overweight and obesity is potentially associated with the following risk factors:

(i) birth weight,

(ii) physical activities (playing outdoors, leisure activities), sedentary

activities (watching television, playing computer/television/hand held video games, reading, drawing and coloring activities),

(iii) socioeconomic status (father’s education, mother’s education, total

combined monthly income),

(iv) breastfeeding, types of breastfeeding, maternal smoking and alcohol

consumption during pregnancy

(v) other factors: duration of preschool hours per day, presence of park or

garden near to home

2.2 Study Design and Study Population

2.2.1 Study Design

It is a cross-sectional study which is part of “A Study on Strabimus, Amblyopia and Refractive Error in Singapore Chinese Preschoolers (STARS)”

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STARS is a population based cross-sectional study to determine the prevalence of eye diseases (mainly myopia, strabismus and refractive error) in 3,000 Chinese children aged 6–72 months in Singapore The STARS study was conducted from February 2006 to November 2008

2.2.2 Study area and Study population

The study areas were South-Western part of Singapore (Bukit Batok, Clementi and Queenstown) and Western parts of Singapore (Jurong East and Jurong West) of Housing Development Board (HDB) apartments These parts of Singapore were chosen because they are close to the Singapore Eye Research Institute and Jurong Medical Centre where the subject assessment and measurements took place Chinese children aged between 6–72 months living in this study area were our study subjects

In Singapore, the total resident population is 3.7 million in which there are 410,107 children (10.8%) aged below 9 years.73 The total resident population in our study areas (South-Western and Western parts of Singapore) is 690,216 and children below 9 years old constitutes 10.9% (75,528).73 Children aged below 1 year constitute 0.9% [n=32,788; boys=16,693 (50.9%), girls=16,095 (49.1%)] in 3.7 million Singapore resident population, compared to our study in which children aged 6 months to below 1 year is 0.03% [n=181; boys=85 (47.0%), girls=96 (53.0%)] Moreover, of which 3.7 million resident population, the proportion of children aged 1 year is 1.0% [n=38,350; boys=19,549 (51.0%),

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girls=18,801 (49.0%), aged 2 years is 1.1% [n=41,562; boys=21,049 (50.6%), girls=20,513 (49.4%)], aged 3 years is 1.1% [n=40,869; boys=20,853 (51.0%), girls=20,016 (49.0%)], aged 4 years is 1.1% [n=40,863; boys=20,746 (50.8%), girls=20,117 (49.2%)] and aged 5 years is 1.1% [n=40,915; boys=20,755 (50.7%), girls=20,160 (49.3%)].73 In our study, aged 1 year constitutes 0.08% [n=527; boys=304 (57.7%), girls=223 (42.3%)], aged 2 years constitutes 0.07% [n=509; boys=257 (50.5%), girls=252 (49.5%)], aged 3 years constitutes 0.08% [n=571; boys=291 (51.0%), girls=280 (49.0%)], aged 4 years constitutes 0.09% [n=601; boys=321 (53.4%), girls=280 (46.6%)] and aged 5 years constitutes 0.08% [n=575; boys=290 (50.4%), girls=285 (49.6%)]

A total of 5,648 preschool children aged 6–72 months were recruited from households in South-Western and Western areas of Singapore and 3,009 (72.2%) children responded

2.2.3 Sampling method

All households located in the South-Western (Bukit Batok, Clementi, and Queenstown) and Western (Jurong East and Jurong West) part of Singapore with Chinese children aged 6–72 months formed the sampling frame Disproportionate stratified random sampling by 6 month age groups was performed To obtain a high response rate and obtain a target sample size of 3,000, total 5,648 children of aged between 6–72 months were recruited

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The approval to conduct the study was obtained from the Institution Review Board (IRB) from Singapore National Eye Centre and Domain Specific Review Board (DSRB) from National Health Group

2.2.4 Inclusion and Exclusion Criteria

Children were eligible if they were aged between 6 months to 6 years and Chinese in which at least one of the parents of the child must be Chinese Exclusion criteria included children aged over 6 years or non-Chinese or children with chronic diseases, children with relevant disabilities or children with congenital abnormalities If the family moved out from this address or the given address was an error, the child was ineligible

Of the 5,648 participants, 4,164 of children were eligible for the study Eligible group was divided into refused, non-contactable and attended groups Children were categorised as refused (n=1,119) if the parents were not interested

to take part in the study, too-busy, had no time or they could not attend because they thought that the clinics were far from their home Non-contactables (n=36) were defined as those who could not be contacted at least 8 times The attended group includes 3,009 participants

Ineligible category includes overage or underage (612 children) 384 children were ineligible because the family moved out Races other than Chinese were also under the ineligible group of “Non-Chinese” subset, and it constituted

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37 children Data error (n=152) was also included in the ineligible group, and

other unknown reason of ineligibility included 299 children

Attended (n=3,009) 72.3%

Non- Chinese (n=37) 2.5%

Others (n=299) 20.2%

Data error (n=152) 10.3%

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2.3.2 Recruitment Process

Brochures of STARS and the invitation letters of both English and Chinese language were sent out to all the households The invitation letter described common eye diseases in preschool Chinese children, the objective of this survey and invitation to participate in this survey Parents who were interested in the survey called back and made an appointment at one of the two clinics For those who did not call back, the door-to-door recruitment process was conducted and guided by recruitment officers

During the home visit, the recruiters explained the objective of STARS and the processes (eye examination after putting eye drops, interview questionnaire about the child’s life style and quality of life) which they will be encountered during the survey The explanation was either in the English or Chinese language depending on the subject’s preference The recruiter also explained about the possible risks of eye drops (mild local allergic reactions, slight temporary difficulty or blurring of vision in reading and mild discomfort while looking at bright lights for 1 to 2 days) which was used to dilate pupils for eye examination If the parents were interested in the study and agreed to bring their child for the survey, the recruiters arranged appointments for them at one of the two clinics

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2.3.3 Clinic Visit

Registration

Taking informed consent

2 Autorefraction (>24months) or Retinomax (<24months)

3 Retinoscopy (if autorefraction or retinomax fails)

4 Fundus photo (>47months)

Give Report and End the survey

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2.3.4 Clinic Visit and Ethics consideration

The children were registered and the qualified optometrist of the survey team explained about the risks and benefits of this survey they participated The parents of the participants were also explained about the confidentiality and autonomy with their child in the whole survey process

If the parents agreed to the survey procedures, they were asked to sign the informed consent form for behalf of their child A copy was given to the parents, and another was kept for the study Even the parents refused to continue participating in the research process, the refusal was respected and the whole entire process of the survey was stopped

2.4 Height and Weight Measurements

Weight was measured in kilograms (kg) to the nearest one decimal point, and height was measured in centimeters (cm) to nearest one decimal point Recruiters who were assigned as examiners in height and weight measurements were trained to perform the same standardized measurement procedures by an experienced general practitioner

The equipments (Seca model 220) used for measuring height and weight for children 2 years old and above, were calibrated once a year

in the pockets, and hair accessories The child was instructed to stand still in the middle of the scale platform, with arms relaxed and hanging down by the side of the body, both feet slightly apart in order to distributed the weight equally

Height was measured using the same machine The child was asked to look straight ahead along the Frankfort Plane The Frankfort plane is the line connecting the superior border of the external auditory meatus with the lower edge of the eye The measuring slide of the telescopic rod was moved in horizontal position till it firmly abut the crown of the head, slightly compressing the hair, without bending the slide The height is noted at the read off mark Accuracy of measurement better than +/- 5 mm can be achieved according to the manufacturer

2.4.2 Measuring Height and Weight of Child less than 2 years

If the child is less than 2 years old, or unable or unwilling to stand unsupported on the scale, the child was measured in the parent’s arms The parent was weighed alone, and then weighed again with child in arms The combined

of the board One examiner brought the child’s head gently to contact with the fixed headboard The second examiner held the child’s feet and toes perpendicular

to the measuring length board, keeping the knees straight and bringing the moveable footboard against the heels If the child was restless, only one leg was positioned for the measurement

2.5 Skinfold Measurements

For child who is 2 years old and above, subcutaneous fat thickness was measured using the Holtain skinfold caliper This caliper was designed to give a constant pressure of 10gms/sq.mm according to manufacturer and marked in divisions of 0.2mm, starting from 0 mm up to 40 mm The dial of the caliper was checked to ensure at zero each time before use Only the triceps site was measured in the study

The right arm was used for this skinfold measurement The child was asked to stand, with back facing the examiner with the arms were relaxed Mid-

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way between tip of acromion and the tip of the olecranon process, a fold of skin, deep enough to get the subcutaneous fat but without picking the triceps muscle was lifted perpendicularly to the surrounding skin with the thumb and forefinger

of the examiner’s left hand The calipers were applied to the fold midway between the crest and the base of the fold, maintaining this fold throughout the measuring process The reading was noted down and the process was repeated another two times to obtain three measurements at the same site An average value was obtained

2.6 Questionnaire

The questionnaire in this study was administered by well-trained interviewers of our research team The questionnaire was adapted and modified from both the SCORM (Singapore Cohort Study of the Risk Factors for Myopia)74 and the quality of life questionnaire of MEPEDS (The Multi-Ethnic Pediatric Eye Disease Study)75

The questionnaire includes family history, birth weight, duration of preschool hours, physical activities, sedentary activities, presence or absence of park or garden near to home, maternal smoking and alcohol consumption history during pregnancy, types of breastfeeding in breastfed mother

Before proceeding with the interview questionnaire to a parent or guardian, the interviewer assured the confidentiality of the information, which was answered by the parent or guardian, and we respected any refusal to answer

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any of the questions if they do not want Informed consents were obtained from the parents or guardians

The questionnaire took about half an hour to complete For those parents

or guardians who are not conversant with the English language, the interviewer used the Chinese language version of the questionnaire

2.6.1 Family History

2.6.1.1 Income

The total income per month of the family were asked for (“What is your total combined monthly household income? [Singapore dollars]”), by interviewing either the father or mother, and classified into four categories: Less than S$1,000, S$1,000–S$2,999, S$3,000–S$4,999, S$5,000 and above There were also ‘Refuse’ and ‘Don’t know’ categories for that question if either father

or mother did not want to answer, or could not estimate the actual the total combined monthly income

2.6.1.2 Education of parents

Educational level of father (“What’s the child father’s completed educational level?”) was classified into seven categories: None, Primary, Secondary, “O”/”N” levels, “A” levels/Polytechnic/Diploma/ITE/Certificate, University education (degree and above, including bachelor, master and PhD) and

The educational level of mother (“What’s the child mother’s completed educational level?”) was also asked as the same way as the father’s education status

2.6.2 Clinic Questionnaire

2.6.2.1 Birth Weight

The parents were asked to bring the child’s health booklet on the appointment day From the health booklet, the information of the child’s birth weight was recorded in grams as an answer to the question “How much did your child weigh at birth?” If the parents cannot remember their child’s birth weight,

‘Don’t know’ category for that question was selected There was also ‘Refuse’ category for those parents did not want to answer that question

2.6.2.2 Preschool Hours

Many children in Singapore attend pre-nursery (3 years old and younger), nursery (4 years old), kindergarten 1st year (5 years old) and kindergarten 2nd year