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Research
Iron deficiency in Australian-born children of Arabic background in
central Sydney
Margaret A Karr, Michael Mira,
Garth Alperstein, Samia Labib
Boyd H Webster, Ahti T Lammi and
Patricia Beal
MJA 2001; 174: 165-168
For editorial comment, see Couper and Simmer
Abstract -
Methods -
Results -
Discussion -
Acknowledgements -
References -
Authors' details
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More articles on Public and environmental health
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Objectives: To determine the prevalence of iron
depletion and deficiency, and iron-deficiency anaemia, along with
risk factors for iron depletion, in Australian-born children aged
12-36 months of Arabic-speaking background.
Design: Community-based survey.
Setting: Central Sydney Area Health Service (CSAHS),
NSW, April to August, 1997.
Participants: All children born at five Sydney hospitals
between 1 May 1994 and 30 April 1996, whose mothers gave an
Arabic-speaking country of birth and resided in the area served by the
CSAHS.
Main outcome measures: Full blood count (haemoglobin,
mean corpuscular haemoglobin, mean corpuscular volume), plasma
ferritin concentration, haemoglobin electrophoresis, potential
risk factors for iron depletion.
Results: Families of 641 of the 1161 eligible children
were able to be contacted, and 403 agreed to testing (response rate,
62.9% among those contacted). Overall, 6% of children had
iron-deficiency anaemia, another 9% were iron deficient without
anaemia, and 23% were iron depleted. Multiple logistic regression
analysis showed three significant independent risk factors for iron
depletion: < 37 weeks' gestation (odds ratio [OR], 5.88, P =
0.001); mother resident in Australia for less than the median time
of 8.5 years (OR, 1.96, P = 0.016); and daily intake of > 600
mL cows' milk (OR, 3.89, P = < 0.001).
Conclusion: Impaired iron status is common among
children of Arabic background, and targeted screening is
recommended for this group.
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Numerous studies have documented the adverse health effects of iron
deficiency in infants and preschool children, including growth
retardation,1,2 gastrointestinal
changes,3 impaired immune
function,4 impaired behavioural and
mental development5,6 and decline in
psychomotor development.7,8 In 1992-1994, a study of
Sydney children aged 9-62 months found that 1.1% had iron-deficiency
anaemia, while 2.8% were iron deficient without anaemia and another
10.5% were iron depleted.9 The prevalence of
iron-deficiency anaemia appeared to be higher among children of
Arabic-speaking background, but the small number of these children
prevented firm conclusions, and the reasons for any difference were
not clear.
The most important determinants of iron status in infants are growth
rate relative to iron endowment at birth, dietary iron content and
bioavailability and gastrointestinal blood loss.10 Risk factors
for iron deficiency in infancy and childhood include prematurity,
low birth weight,11,12 exclusive
breastfeeding beyond six months of age,13 introduction of whole
cows' milk before 12 months of age,14 and high intake of cows'
milk.15
We examined the prevalence of impaired iron status in a large group of
Australian-born children of Arabic-speaking background and
evaluated their risk factors for iron depletion.
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The study was a community-based survey undertaken between April and
August 1997.
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Participants |
Children were identified from the medical records of five Sydney
hospitals, which, according to the Midwives Data Base, account for
92% of deliveries to mothers born in an Arabic-speaking country and
residing in the area served by the Central Sydney Area Health Service
(CSAHS).16 Eligibility criteria
were:
- birthdate between 1 May 1994 and 30 April 1996;
- mother gave an Arabic-speaking country of birth on admission;
- postcode of mother's place of residence was in the area served by the
CSAHS.
Hospitals were asked to exclude stillbirths and neonatal deaths.
Contact details were obtained from the medical records.
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Survey |
Parents of all eligible children were sent a letter about the study in both Arabic and English. Five days later, they were telephoned
to discuss queries and to invite their child's participation. If they
agreed, an appointment was made at a convenient early childhood
health centre, or a home visit was arranged. Parents were asked to
bring the child's Personal Health Record for assessment of birth
weight and gestation.
Demographic data were obtained using a structured questionnaire
administered by an Arabic-speaking research assistant (S L).
Questions were also asked about the child's feeding habits since
birth and whether the child had had a fever in the two weeks before the
blood test, as fever can elevate plasma ferritin
concentration.17 |
Investigations | |
About 0.75 mL of blood was collected by fingerprick and tested at the
Royal Alexandra Hospital for Children (RAHC), Sydney, NSW.
Haematological investigations (using a Coulter S+IV, Fullerton, Cal, USA) included
measurement of haemoglobin and red cell indices. Plasma ferritin
concentration was measured by immunoradiometric assay (Biorad,
Hercules, Cal, USA). Haemoglobin electrophoresis was performed on
all samples to detect haemoglobinopathies. Definitions of impaired
iron status are shown in Box 1.
All parents were notified of their children's results. Children with
poor iron status or haemoglobinopathy were referred to their general
practitioners (GPs). A copy of the laboratory report was sent to the GP
and to the parents, if they so requested.
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Statistical analyses | |
Children found to have a haemoglobinopathy were excluded from the
analyses, which were performed using Stata (version 5).21 Statistical
tests were performed after adjustment for possible cluster effects
both within hospitals and within families (as some families
contributed more than one child to the study). Confidence
intervals were similarly adjusted. Adjusted χ2 tests were used
to examine relationships between iron depletion and demographic and
risk factors. Variables found to be significantly
associated with iron depletion were then entered into a multivariate
logistic regression model.
Prevalence of impaired iron status was compared with prevalence in
children from the general population of central Sydney assessed in
1992-1994.9 Data from that study were
re-examined for children aged 12-38 months, using a ferritin level
< 10 µg/L to define iron depletion.
To test the representativeness of our sample group, demographic
characteristics of the mothers were compared with those of all women
who in the 1996 census gave an Arabic-speaking country of birth,
resided in the area served by the CSAHS, were aged 15-45 years and had
children aged 12-38 months. These data were obtained from the
Australian Bureau of Statistics.
Ethical approval for all components of this study was obtained from
the CSAHS Ethics Review Committee. All participating parents gave
informed written consent.
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| Results |
We were able to contact families of 641 of the 1161 eligible children
and tested 403 of these children (63% response rate among those able to
be contacted). Haematological testing identified a
haemoglobinopathy in 21 children, who were therefore excluded from
analysis, although two had other haematological parameters
consistent with iron depletion. This left 382 children with a plasma
ferritin result, and 315 with complete haematological results
(blood volume was insufficient for a complete examination in the
other 67).
Median age of the 382 children at the time of data collection was 25
months (range, 12-38 months). Age distribution was 12-23 months (149
children), 24-35 months (204), and 36-38 months (29). Just over half
the children (53%) were male.
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Prevalence of impaired iron status | |
Prevalence of impaired iron status is shown in Box 2. Overall, 38% of
children with an Arabic background had impaired iron status,
comprising 6% with iron-deficiency anaemia, a further 9% with iron
deficiency without anaemia and a further 23% with iron depletion. The
Box also shows prevalences found in 1992-1994 among children the same
age in the general population of central Sydney.9 The proportion
of children with impaired iron status was substantially higher among
Australian-born children of Arabic-speaking background in 1997
than among children of the same age in the general community in
1992-1994.
Among the children of Arabic background, those who were reported as
having a fever in the two weeks before the blood test were
statistically less likely to fulfil the criteria for iron depletion
(19/122 versus 68/260; F1,339 = 5.07; P =
0.025). However, they did not differ significantly in rates of
iron deficiency (11/108 versus 16/207; F1,282 =
0.49; P = 0.48) or iron-deficiency anaemia (8/108 versus
12/207; F1,282 = 0.31; P = 0.58). The rate
of iron depletion among the 260 children reported not to have had a
fever in the two weeks before the blood test was 26% (95% CI, 21%-32%).
There were no significant differences in iron status between the
sexes or between age groups.
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Risk-factor analysis | |
Potential risk factors among the 382 children are shown in Box 3.
Univariate analysis revealed that prematurity, mother resident in
Australia less than the median time of 8.5 years, mother born in a
country other than Lebanon, and daily intake of more than 600 mL of
cows' milk were significantly associated with iron depletion (Box
4). None of the other variables tested, including age of introduction
of cows' milk, were significantly associated with iron depletion.
Multivariate logistic regression analysis determined that
prematurity, mother resident in Australia less than the median time
of 8.5 years, and daily intake of more than 600 mL of cows' milk, but not
mother born in a country other than Lebanon, were independently
associated with iron depletion (Box 4). Children who had been born
prematurely were almost six times more likely to be iron depleted,
while those who drank more than 600 mL cows' milk per day were almost
four times as likely and those whose mothers had been in Australia less
than the median time (8.5 years) were almost twice as likely.
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Representativeness of sample | |
We compared post-secondary education and time in Australia between
the sample group and all women who in the 1996 census gave an
Arabic-speaking country of birth, resided in the area served by the
CSAHS, were aged 15-45 years and had children aged 12-38 months. In the
sample group, 29% (116/403) had post-secondary qualifications (95%
CI, 24%-33%), compared with 30.2% in the census group (421/1392).
Similarly, 30% (121/401) of our sample had been in Australia for six to
10 years (95% CI, 26%-35%), while the corresponding figure for the
census group was 26.4% (368/1392).
The 238 parents who declined a blood test for their child were
questioned by telephone about the age and sex of the child and the
volume of cows' milk consumed daily; 180 parents (76%) responded.
There were no significant differences between their children and
those who had blood tests in age (P = 0.7), sex (P = 0.6)
or reported volume of cows' milk consumed daily (P = 0.17).
Among the 382 children tested for iron depletion, 67 had moved place of
residence since birth and 315 had not moved. The proportion with iron
depletion did not differ between these two groups (OR, 1.31; 95% CI,
0.73-2.36). Nor did it differ between the 67 children who had only
ferritin level estimated and the 315 who gave sufficient blood for a
full haematological examination (OR, 1.03; 95% CI, 0.53-2.01).
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These results indicate a public health problem in Australian-born
children of Arabic-speaking background in central Sydney that could
indicate a nationwide problem. More than a third of these children had
impaired iron status, including 6% with iron-deficiency anaemia and
another 9% with iron deficiency without anaemia. These
prevalences are higher than those found in children the same age in the
general population of central Sydney in 1992-1994.9 There are several potential sources of bias in this study. The first
was the use of retrospective records and consequent failure to
contact about 45% of mothers. This is a common problem in such
retrospective studies.22,23 However, the mothers
of the children studied did not differ significantly from all women in
the 1996 census who were aged 15-45 years with children in the target
age range, gave an Arabic-speaking country of birth and resided in the
CSAHS, while prevalence of iron depletion did not differ between
children who had moved residence since birth and those who had not. It
is unlikely that our sample differed substantially from the total
study population.
A second potential source of bias was non-response. However,
children whose parents refused a blood test did not differ
significantly from those who had a blood test in age, sex and
proportion who drank more than 600 mL cows' milk daily. Finally,
children whose blood samples were insufficient for full
haematological assessment did not differ significantly in
prevalence of iron depletion from those who had a full assessment.
In the group of children reported to have had a fever in the two weeks
before the blood test, a significantly lower proportion fulfilled
the criteria for iron depletion. Therefore, the rate of iron
depletion reported may be an underestimate.
The definition of iron deficiency used in this study was particularly
stringent, requiring abnormal values for three laboratory
indicators of iron status. Criteria used by the United States Third
National Health and Nutrition Examination Survey were less
stringent: individuals were diagnosed as iron-deficient if they had
abnormal values for two of three laboratory indicators (serum
ferritin, free erythrocyte protoporphyrin or transferrin
saturation).18 Nevertheless, that
survey found rates of iron deficiency and iron-deficiency
anaemia among children aged one to two years less than half the rates
found in our study (3% versus 6% in our study). The US rate was similar to
the rate found in children in the general population of central Sydney
in 1992-1994.
Risk of iron depletion in our study was greater in children whose
mothers had been in Australia for less than the median time of 8.5
years. About 79% of these mothers spoke Arabic, or mainly Arabic, in
the home. Early childhood health centres in central Sydney have
specific days on which an Arabic interpreter is present, but
anecdotal reports suggest that many mothers do not avail themselves
of this service. Newly arrived mothers should be targeted in
hospital, immediately postpartum, and given information as to which
days an Arabic interpreter will be at their local centre and strongly
encouraged to attend on a regular basis.
Prematurity is well documented as a risk factor for iron deficiency,
and this should be kept in mind by GPs and other healthcare providers.
Of particular interest is the risk associated with the volume of cows'
milk consumed daily. The National Health and Medical Research
Council recommends that children aged under 12 months should not
receive cows' milk as the main source of milk, while those aged over 12
months should not receive more than 600 mL per day.24 In the
multiple logistic regression model, children who consumed more than
600 mL per day were almost four times as likely to have iron depletion,
and targeted screening is strongly indicated based on this dietary
history. Cows' milk is a poor source of iron, displaces foods with
greater available iron and may also increase gastrointestinal
occult blood loss. GPs should be aware of the importance of a dietary
history for children of Arabic-speaking background and should
enquire particularly about the volume of cows' milk consumed per day
after 12 months of age.
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Acknowledgements | |
We wish to thank the parents and children who participated in this
study, the haematology laboratory staff at the Royal Alexandra
Hospital for Children, Sydney, and the nurses of the participating
Early Childhood Health Centres. The blood collection skills of Mrs
Rhonda Dryden were invaluable to this study. The study was funded by
the National Health and Medical Research Council Public Health
Research Development Committee, Grant No: 97-417-7.
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| References |
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Prasad AN, Prasad C. Iron deficiency; non-hematological
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Berant M, Khourie M, Menzies IS. Effect of iron deficiency on small
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Thibault H, Galtn P, Selz F, et al. The immune response in
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Oski FA, Honig AS, Helu B, Howanitz P. Effect of iron therapy on
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Lozoff B, Jiminez E, Wolf AW. Long-term developmental outcome of
infants with iron deficiency. N Engl J Med 1991; 325: 687-694.
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Williams J, Wolff A, Daly A, et al. Iron supplemented formula milk
related to reduction in psychomotor decline in infants from inner
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Walter T, De Andraca I, Chadud P, Perales CG. Iron deficiency
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Karr M, Alperstein G, Causer J, et al. Iron status and anaemia in
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Dallman PR, Siimes MA, Stekel A. Iron deficiency in infancy and
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Gorten MK, Cross ER. Iron metabolism in premature infants: 2.
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Friel JK, Andrews WL, Matthew JD, et al. Iron status of
very-low-birth-weight infants during the first 15 months of
infancy. CMAJ 1990; 143: 733-737.
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Calvo EB, Galindo AC, Aspres NB. Iron status in exclusively
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Penrod JC, Anderson K, Acosta PB. Impact on iron status of
introducing cow's milk in the second six months of life. J Pediatr
Gastroenterol Nutr 1990; 10: 462-467.
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Mills AF. Surveillance for anaemia: risk factors in patterns of
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NSW Department of Health, NSW Midwives Data Collection, 1994.
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Elin RJ, Wolff SM, Finch CA. Effect of induced fever on serum iron
and ferritin concentrations in man. Blood 1977; 49: 147-153.
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Looker AC, Dallman PR, Carroll MD, et al. Prevalence of iron
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Dallman PR, Siimes MA. Percentile curves for hemoglobin and red
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Dallman PR, Looker AC, Johnson CL, Carroll M. Influence of age on
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iron deficiency in infants and children. In: Hallberg L, Asp N-G,
editors. Iron nutrition in health and disease. London: J Libbey,
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Stata statistical software release 5.0 [computer program].
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McBride WG, Black BP, English BJ. Blood lead levels and behaviour
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Ranmuthugala G, Karr M, Mira M, et al. Opportunistic sampling from
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(Received 2 Mar, accepted 1 Sep, 2000)
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Central Sydney Area Health Service, Sydney, NSW.
Margaret A Karr, MPH, MSc(Med), Senior Research Officer,
Division of General Practice;
Michael Mira, MB BS, PhD,
Clinical Professor, Department of General Practice, University of
Sydney;
Garth Alperstein, FRACP, Paediatrician and
Clinical Senior Lecturer, University of Sydney, and Conjoint Senior
Lecturer, University of New South Wales, Sydney, NSW;
Samia
Labib, BA, MEd(Health), Senior Interpreter, Health
Interpreter Service.
Department of Haematology, Royal Alexandra Hospital for Children,
Sydney, NSW.
Boyd H Webster, FRCPA, Senior Staff Specialist;
Ahti T
Lammi, FRACP, FRCPA, Senior Staff Specialist;
Patricia
Beal, MSc, Senior Hospital Scientist.
Reprints will not be available from the authors.
Correspondence:
Professor M Mira, General Practice Casualty, Balmain Hospital,
Booth Street, Balmain, NSW 2041.
michaelmira_auATyahoo.co.uk
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| 2: Prevalence of impaired iron status among
children aged 12-38 months of Arabic background in central Sydney in 1997 |
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Arabic background |
General population9 |
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| Iron status* |
Number |
% (95% CI) |
Number |
% (95% CI) |
|
Iron depletion
Iron deficiency
Iron-deficiency anaemia |
87/382
27/315
20/315 |
23% (19%-27%)
9% (5%-12%)
6% (4%-9%) |
36/381
14/329
5/329 |
9% (7%-12%)
4% (2%-7%)
2% (0-3%) |
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| *Definitions of iron status in
children of Arabic background are shown in Box 1. The same definitions were
used for children in the general population, except that iron deficiency
was defined as iron depletion plus mean corpuscular volume < 70fL (age, 12-23
months) or < 73fL (age, 24-38 months), or red cell zinc protoporphyrin level
> 80µmol/mol haem. |
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| 3: Potential risk factors for iron depletion
among 382 children aged 12-38 months of Arabic background in central Sydney,
1997 |
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Children with |
Children without |
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| Potential risk factors |
iron depletion |
iron depletion |
P* |
|
| Born before 37 weeks' gestation |
12/87 (14%) |
10/295 (3%) |
0.001 |
| Birth weight |
7/86 (8%) |
8/293 (3%) |
0.05 |
| Breastfed initially |
70/87 (81%) |
245/295 (83%) |
0.59 |
| Breastfed at time of data collection |
4/87 (5%) |
9/295 (3%) |
0.49 |
Cows' milk introduced before age of
12 months |
32/87 (37%) |
76/295 (26%) |
0.06 |
Cows' milk introduced before age of
9 months |
15/87 (17%) |
36/295 (12%) |
0.20 |
Consume >600mL cows' milk
per day |
54/83 (65%) |
109/287 (38%) |
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| Consume ≥1L cows' milk per day |
23/83 (28%) |
30/287 (11%) |
|
| Iron-fortified cereal as first solid |
38/87 (44%) |
149/295 (51%) |
0.27 |
| Consume meat |
42/87 (48%) |
122/295 (41%) |
0.26 |
| Receiving vitamin supplement |
3/87 (3%) |
11/295 (4%) |
0.90 |
Receiving iron-containing
supplement |
1/87 (1%) |
4/295 (1%) |
0.88 |
| Mother not born in Lebanon |
26/87 (30%) |
49/295 (17%) |
0.01 |
Arabic or mainly Arabic spoken
at home |
58/87 (67%) |
180/293 (61%) |
0.39 |
Mother resident in Australia less
than median
time (8.5 years) |
53/86 (62%) |
137/294 (47%) |
0.02 |
|
| *By adjusted χ2
test. |
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