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Vitamin D Deficiency and Its Predictors in a

Country with Thirteen Months of Sunshine:

the Case of School Children in Central

Ethiopia

NNP related research finding dissemination workshop

Oct. 23-25, 2014

Adama, Ethiopia

Federal Democratic Republic of Ethiopia

Tolassa Wakayo (BSc, MSc)1

Tefera Belachew (Professor)2

Susan J Whiting (Professor)3

Jimma University1, 2, University of Saskatchewan3

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Presentation outline

Introduction

Objective

Hypothesis

Methods

Results

Conclusion

Recommendation

Implication

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Introduction

Micronutrient deficiencies are common world-wide and

adversely affect growth, health, behavioural and cognitive

development in children and adolescents (Khor et al., 2011).

Adolescence is the most critical period in skeletal

development,

– Rapid growth→increase in bone mass

• ↑ need for calcium and vitamin D (Guillemant et al.,

1999, 2001; Fares et al., 2003).

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Introduction…cont’d

Role of vitamin D in human body;

calcium and phosphate absorption and homeostasis

bone health,

non-calcemic functions;

– immune function, cellular differentiation, and

– preventing cancer, multiple sclerosis, DM, and

CVD (Garanty-Bogacka et al., 2011; Grant, 2006;

Neyestani et al., 2011).

Two different forms: vitamin D2 & vitamin D3 .

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Introduction…cont’d

Hands, face and arms – sufficient vitamin D3

– duration of exposure, time of day, season, latitude, skin

pigmentation, solar elevation angle as well as the surface and

atmospheric conditions.

Recommended exposure times must account for skin type and

changes in the radiative regime.

Skin type I, II, III, IV, V, and VI→16, 20, 25, 37, 49, and 83

minutes,

– for adequate vitamin D3 synthesis in their skin (Arabi,

2010; Webb and Engelsen, 2006).

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Introduction…cont’d

Vitamin D deficiency is a public health problem worldwide,

– even in countries with enough sunshine year round to promote

adequate skin synthesis (Andıran et al., 2011; Whiting &

Calvo, 2011).

There are few studies that look at vitamin D status in children

living in sunny climates

– as it is assumed that they receive adequate vitamin D from sun

exposure.

But, no study has been done on vitamin D status among

children living in Ethiopia.

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Research Objective

General objective

To determine vitamin D status and its predictors among

school children in Adama Town and rural kebeles of Adama

Woreda aged 11-18 years.

Specific Objectives

To determine vitamin D status among school children in urban

of Adama Town and surrounding rural kebeles.

To evaluate the difference of vitamin D status between school

children in urban of Adama Town and rural kebeles.

To identify predictors of vitamin D status among study

subjects.

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Research Hypothesis

There is significant proportional difference of vitamin D

status between urban and rural school children in Adama

Town and rural kebeles of Adama Woreda aged 11-18

years.

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Methods and MaterialsStudy Area

Characteristics Adama Town Adama Woreda

Altitude 1,785m(1600m-1970m) 1,852m (1400-2304m)

Latitude 8˚33’ to 8˚36’N 8˚30’ to 8˚45’N

Dry season October to February October to February

Rainy season June to September June to September

Average RF 869.3mm 867mm

Average T° 21.3˚C(7.6˚C to 34.5˚C) 22.5˚C (12˚C to 33˚C )

Average daily

sunshine duration

8.4hrs/day 8.2hrs/day

Total population 220,212 (2007 Census) 155,321 (2007 Census)

Edu. coverage 97% >80%

Health Coverage 100% 100%

Main crops maize, teff, sorghum, wheat, barley, peas, bean and

various types of oil seeds

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Methods….cont’d

Study period

May – June , 2013.

Study design

Institution based cross-sectional study

Population

♦Source population

─All school children in primary and secondary schools in

both Adama Town and rural kebeles of Adama Woreda

aged 11-18 year.

♦Study population

─Selected school children in selected primary and secondary

schools in both Adama Town and rural kebeles of Adama

Woreda aged 11-18 year.

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Methods….cont’d

Sample size determination

Two population proportions (P1-P2);

Where;

P1 (rural school children) = 58% as reported by Sahu et al.

(2009) among rural school children in India.

P2 (urban school children) = 78% (assumed in advance to be

greater than that of rural school children at least by 20% ).

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Methods….cont’d

α = 5%

1- β (power)=80%

n=

Adding 10% non response rate, 89 subjects from each setting.

Thus, a total of 178 subjects were required for achieving an

80% power.

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Methods….cont’d

Exclusion criteria

History of chronic or recent (previous two weeks) illness;

─ known diagnoses of liver, or kidney diseases

History of taking medications like;

─anticonvulsants and steroids

Age less than 11 year or greater than 18 year

Skin hypopigmentation due to major burn or other

dermatological problems

Unwilling to give assent themselves or informed written

consent by their parents/guardians

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Methods….cont’d

Sampling technique

Multi-stage stratified sampling procedure that involved two-

stages of sampling was used.

– Schools were selected randomly and sample sizes (n=89 each)

were distributed to each school using proportional to size

allocation formula.

– Children in each selected school were stratified (sex and age)

and proportional to size allocation formula was used once

again to distribute allocated samples to each stratum.

Finally, children from each stratum were selected using SRS.

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Methods….cont’d

Data collection

♦Data collection methods

*Anthropometric Measurements

Anthropometric data: TANITA electronic scale, portable

stadiometer and Holtain skin caliper.

All height, weight and skin folds were measured 3 times as

per WHO standardized procedure and the means were used

for analysis.

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Methods….cont’d

*SE, BSA and skin color assessment

The SE status and BSA: pretested structured questionnaire.

Skin colors of the subjects were classified into three groups as

• light brown

• dark brown objectively by PI.

• very dark

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Methods….cont’d

*Collection of dried blood spots

Invitation of parents/guardians of the selected children.

Objectives of the study were fully explained in open session.

–informed written consent ─parents/guardians

–verbal assent ─children

blood drops (at least two) taken from finger prick.

air dried for at least 30 minutes.

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Methods….cont’d

Once dried,

– flaps were closed and stored in a sealed Ziploc bag with

• desiccants and moisture indicators.

Oromia Public Health Research, Capacity Building and

Quality Assurance Laboratory , on regular bases.

Stored at ̶ 80˚C→ZRT laboratory, Oregon, USA.

The maximum duration -2 months.

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Methods….cont’d

*Biochemical Analysis

Circulating 25(OH)D was analyzed from DBS in the present

study.

in agreement with determining it from serum and whole

blood samples (Hassan et al., 2013, www.zrtlab.com).

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Methods….cont’d

Study setting

Age of a child

Sex of a child

Religion of a child

BMI of a child

TSF of a child

Skin pigmentation of a child

Duration of SE of a child

BSA exposed to the sunlight

Parental demographic chics

Parental SES

Having TV/computer in the home

Study Variables

Dependent variable

Vitamin D status

Independent variables

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Methods….cont’d

Statistical analysis

Entered in double, checked for missing values and outliers,

and analyzed using SPSS for window version 16.

First, bivariate analyses – candidate variables.

Second, multivariable analyses – predictors.

two-sided and p <0.05 was considered significant.

Odds Ratio and 95% CI.

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Methods….cont’d

Ethical Clearance

– Hawassa University IRB

– University of Saskatchewan Ethics Review Board

– NRERC of the Ethiopian Ministry Science and Technology

Quality Control Measures

– well designed study design

– calibrated data collection instruments

– completeness and consistency of data checked.

– 5 days training was given for data collectors

– DBS samples safety assured

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Results

174 students from both study settings,

urban 89(51.1%) and rural 85(48.9%) –response rate 98%.

Table 1: Socioeconomic and demographic characteristics of the

study subjects in Adama Town and Adama Woreda, Ethiopia,

May, 2013.

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Characteristics

(n=174)

N (%)

Urban (n=89) Rural (n=85)

Gender Male 35 (39.3) 40 (47.1)

Female 54 (60.7) 45 (52.9)

Age groups 11-14 26 (29.2) 51 (60)

15-18 63 (70.8) 34 (40)

Religion Christians 55 (61.8) 84 (98.8)

Muslims 34 (38.2) 1 (1.2)

Educational status (father) No formal education 7 (7.9) 47 (55.3)

Formal education 82 (92.1) 38 (44.7)

Educational status (mother) No formal education 17 (19.1) 60 (70.6)

Formal education 72 (80.9) 25 (29.4)

Occupation (Father) Farmer 11 (12.4) 72 (84.7)

Merchant 24 (27) 4 (4.7)

Employed 54 (60.7) 9 (10.6)

Occupation (Mother) House wife 52 (58.4) 78 (91.8)

Merchant 17 (19.1) 1 (1.2)

Employed 20 (22.5) 6 (7.1)

Socioeconomic index Low 20(22.5) 22 (34.1)

Medium 14 (15.7) 38 (44.7)

High 55 (61.8) 18 (21.2)

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Results …cont’d

Overall prevalence of deficiency (serum 25(OH)D <50

nmol/L) in the entire group was 42%.

The proportion of deficiency being significantly higher;

– 61.8% in urban setting

– 21.2% in rural setting

• Zc=5.6; p <0.001.

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Results …cont’d

Vitamin D status

Variables

(n=174)

Deficient Normal COR (95%CI) AOR (95%CI)

Number (%) Number (%)

Setting

Urban 55 (61.8%) 34 (38.2%) 6.02 (3.07, 11.81) 10.53 (3.94, 28.17)

Rural 18 (21.2%) 67 (78.8%) Reference Reference

Sex

Male 22 (29.3%) 53 (70.7%) Reference Reference

Female 51 (51.5%) 48(48.5%) 2.56(1.34, 4.83) 1.76 (0.81, 3.83)

Table 2: Odds ratios of vitamin D status for demographic, socioeconomic,

study setting, BMI, TSF, sun exposure, body surface area exposed (logistic

regression analysis) for school children in Adama Town and Adama Woreda,

Ethiopia, May, 2013.

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Results …cont’d

Variables

(n=174)

Deficient Normal COR (95%CI) AOR (95%CI)

n(%) n(%)

Age groups

11-14 25 (32.5%) 52 (67.5%) Reference Reference

15-18 48 (49.5%) 49 (50.5%) 2.04 (1.1, 3.79) 1.43 (0.66, 3.09)

Religion

Muslims 24(68.6%) 11 (31.4%) 4.01 (1.81, 8.87) 1.61 (0.6, 4.32)

Christians 49(35.3%) 90(64.7%) Reference Reference

Edu. father

Formal 58 (48.3%) 62 (51.7%) 2.43 (1.21, 4.87) 2.4 (0.96, 5.98)

No formal 15 (27.8%) 39 (72.2%) Reference Reference

Edu. mother

Formal 51 (52.6%) 46 (47.4%) 2.77 (1.47, 5.23) 2.74 (1.23, 6.12)

No formal 22 (28.6%) 55 (71.4%) Reference Reference

Table 2: Continued…

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Results …cont’dTable 2: Continued…

Variables

(n=174)

Deficient Normal COR (95%CI) AOR (95%CI)

n(%) n(%)

BMI Class

≥85th per 9 (75%) 3 (25%) 4.59 (1.2, 17.62) 4.67 (0.7, 31.07)

<85th per 64 (39.5%) 98 (60.5) Reference Reference

TSF Class

≥90th per 14 (77.8%) 4 (22.2%) 5.96(1.81, 18.31) 6.1 (1.24, 28.57)

<90th per 97 (62.2%) 59 (37.8%) Reference Reference

SE-school

days

<30 min 27 (81.8%) 6 (18.2%) 15.43 (5.62, ) 13.92 (4.3, 45.1)

30-60 min 25 (52.1%) 23 (47.9%) 3.79 (1.77, 7.86) 5.58 (2.3, 13.85)

≥60 min 21 (22.6%) 72 (77.4%) Reference Reference

BMI=body mass index; TSF= triceps skin fold thickness; SE= sun exposure

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Results …cont’d

Variables

(n=174)

Deficient Normal COR (95%CI) AOR (95%CI)

n(%) n(%)

BSA-school

days

Face, hands

and feet

36 (78.3%) 10 (21.7%) 8.85 (3.99, 19.67) 13.38 (4.69, 38.21)

More than*

face, hands

and feet

37 (28.9%) 91(71.1%) Reference Reference

SE-week

end days

<30 min 31 (72.1%) 12 (27.9%) 8.07 (3.59, 18.14) 7.25 (2.53, 20.75)

30-60 min 18 (56.2%) 14 (43.8%) 4.02 (1.74, 9.27) 9.41 (3.35, 26.39)

≥60 min 24 (24.2%) 75 (75.8%) Reference Reference

More than*:neck, forearms, upper arms, and legs; BSA=Body Surface Area

exposed; SE=sun exposure

Table 2: Continued…

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Results …cont’d

Table 2: Continued…

Variables

(n=174)

Deficient Normal COR (95%CI) AOR (95%CI)

n(%) n(%)

BSA on week

end days

Face, hands

and feet

25 (80.6%) 6 (19.4%) 8.25 (3.17, 21.46) 19.57 (5.53, 69.21)

More than*

face, hands

and feet

48 (33.6%) 95 (66.4%) Reference Reference

Skin color

Light brown 14 (35.9%) 25 (64.1%) Reference Reference

Dark brown 39 (39.8%) 59 (60.2%) 1.18 (0.55, 2.55) 1.18 (0.46, 3.13)

Very dark 20 (54.1%) 17 (45.9%) 2.10 (0.84, 5.27) 1.26 (0.39, 4.1)

More than*:neck, forearms, upper arms, and legs; BSA=Body Surface Area exposed

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Results …cont’d

Variables

(n=174)

Deficient Normal COR (95%CI) AOR (95%CI)

n(%) n(%)

TV/Comp.

in the home

Yes 54 (58.7%) 38 (41.3%) 4.71 (2.44, 9.12) 7.84 (3.19, 19.27)

No 19 (23.2%) 63 (76.8%) Reference Reference

SES

Low 16 (27.6%) 42 (72.4%) Reference Reference

Medium 17 (32.1%) 36 (67.9%) 1.3 (0.58, 2.93) 1.72 (0.59, 5.03)

High 40 (65.6%) 21 (34.4%) 5.24 (2.4, 11.42) 9.4 (3.19, 27.51)

SES=socioeconomic status, NA=not applicable; TV/comp=television/computer

Table 2: Continued…

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Conclusion

Vitamin D deficiency was prevalent among healthy school children both

in urban and rural settings, with the prevalence being significantly

higher among urban school children.

In general, study setting, maternal education, TSF, SE, BSA, having

TV/computer in the home and SES of parents were significantly

associated with vitamin D status of our study subjects.

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Recommendation

1. Public education (especially those who stay indoors most of the time of

a day such as school children and children living in larger cities)

– about safe sun exposure and its importance in maintaining adequate

serum 25(OH)D levels and thus, bone health.

2. Children and their parents (especially those who are economically

better and have better education) need to be well educated on;

– importance of maintaining their kids healthy weight and healthy eating

habits

– risk of wearing concealing clothes for most time of a day

– risk of greater indoor activities for most time of a day

3. Further study is required to assess the deleterious effect of its

deficiency on bone mineral homeostasis of growing children during

their most critical period of bone development.

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Implication of the studyVitamin D is an essential nutrient for linear growth of bones

and for reaching peak bone mass among children and

adolescents.

The government of Ethiopia has targeted children and

adolescents in the national nutrition program for accelerated

stunting reduction and various interventions are underway.

The high prevalence of vitamin D deficiency demonstrated by

this study in a country where there is ample sunlight

throughout the year calls for arguments to include BCCs on

the importance of exposure to sunlight.

This could be done via inclusion of key messages in the

school curricula in the long term and establishing school

nutrition clubs and other relevant educational strategies in the

short run to curb the long term complications of vitamin D

deficiency.

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Acknowledgement

Hawassa University, SNFST

Hawassa University IRB

University of Saskatchewan ERB

NRERC

Oromia Regional Health Bureau

Oromia Regional laboratory

Adama Town & East Shoa Zone Health Offices

Adama Town & East Shoa Zone Education Offices

Schools

Study subjects and their parents

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Thank you!!