Prevalence and associated risk factors of anemia in children and adolescents with intellectual disabilities
Jin-Ding Lin
a,*, Pei-Ying Lin
a, Lan-Ping Lin
b, Shang-Wei Hsu
c,
Ching-Hui Loh
d, Chia-Feng Yen
b, Wen-Hui Fang
d, Wu-Chien Chien
a, Chi-Chieh Tang
e, Chia-Ling Wu
faSchool of Public Health, National Defense Medical Center, No. 161, Min-Chun East Road, Section 6, Nei-Hu, Taipei 114, Taiwan
bGraduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
cGraduate Institute of Healthcare Administration, Asia University, Taichung, Taiwan
dDepartment of Family and Community Medicine, Tri-Service General Hospital, Taipei, Taiwan
eDepartment of Early Childhood Care & Education, Pingtung Education University, Pingtung, Taiwan
fResearch Center for Intellectual Disabilities Taiwan, Chung-Hua Foundation for Persons with Intellectual Disabilities, Taipei County, Taiwan
A R T I C L E I N F O
Article history:
Received 25 July 2009 Accepted 25 July 2009
Keywords:
Anemia Hemoglobin (Hb) Intellectual disability
A B S T R A C T
Anemia is known to be a significant public health problem in many countries. Most of the available information is incomplete or limited to special groups such as people with intellectual disability.
The present study aims to provide the information of anemia prevalence and associated risk factors of children and adolescents with intellectual disability in Taiwan. We analyzed physical examination charts of 937 children and adolescents with intellec- tual disability at the age of 6–18 years from three special schools.
We collected information on their demographic characteristics (age and gender), disability condition (type and level), BMI (weight and height) and measured blood hemoglobin concentration (Hb). There were 11.6% of children and adolescents with intellectual disability with anemia (boy <13 g/dl, girl <12 g/dl), and the factors of gender, age, disability level and BMI are significantly correlated to anemia in bivariant analyses in the study. In the logistic regression analysis, the model revealed that the factors of gender (OR = 0.63, 95%
CI = 0.41–0.95), and age (OR = 3.21, 95% CI = 1.77–5.82) were vari- ables that could significantly predict the anemia occurrence of the participants. The study highlights the anemia prevalence in children and adolescents with ID is a mild public health problem
* Corresponding author. Tel.: +886 2 87923100x18447; fax: +886 2 87923147.
E-mail address:a530706@ndmctsgh.edu.tw(J.-D. Lin).
Contents lists available atScienceDirect
Research in Developmental Disabilities
0891-4222/$ – see front matter ß 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.ridd.2009.07.017
1. Introduction
Anemia is a global public health problem affecting populations in both rich and poor countries with major consequences for human health as well as social and economic development (de Benoist, McLean, Egli, & Cogswell, 2008). The definition of anemia has attracted considerable interest recently because of epidemiologic studies that suggest that anemia may be associated with poorer outcomes in a variety of disorders (Beutler & Waalen, 2006). In many studies the definition of anemia used is that suggested by a WHO expert committee nearly 40 years ago. However, there is a general lack of accurate data on its prevalence throughout the world (Blanc et al., 1968).
In the US, the prevalence of anemia is usually defined in terms of the percentage of individuals with hemoglobin (Hb) values below a 95% reference range (Dallman, Yip, & Johnson, 1984). Measuring Hb concentration is relatively easy and inexpensive, and this measurement is frequently used as a proxy indicator of iron deficiency anemia (de Benoist et al., 2008). Using these reference standards, the prevalence of anemia among the US 15,093 individuals with complete laboratory results was highest in infants (5.7%), teenage girls (5.9%), young women (5.8%), and elderly men (4.4%).
Although hematological complications associated with ID are rare in the previous studies (Pavithran & Raji, 2003). However, the individuals with ID form one of the most vulnerable groups of the disabled population, being more likely to have poorer health status and accompanied with comorbidity, require more medical resources and experience greater difficulty with healthcare accessibility than the general population (Hsu et al., 2009; Lin et al., 2009a; Lin, Lin, Yen, Loh, & Chwo, 2009; Lin et al., 2007, 2006; Lin, Wu, & Lee, 2004; Lin, Yen, Li, & Wu, 2005; Yen, Lin, Loh, Shi, & Hsu, 2009).Hurtado, Claussen, & Scott (1999)conducted a population-based study in the US and found that an increased likelihood of mild or moderate ID was associated with anemia. For each decrement in Hb concentration, the risk of mild or moderate retardation increased (1.28) after several potential confounders were controlled for. Birth weight, maternal education, sex, and age of the mother also predicted anemia, but the odds ratio in each of these cases was >1.28 in a logistic regression model.
Ohwada, Nakayama, Nara, Tomono, and Yamanaka (2006)analyzed from a health checkup data of a public facility for people with ID (N = 477), they found that the prevalence of anemia (Hb value 13.4 g/
dl for males and 11.2 g/dl for females) among male participants was higher than in female participants for each disability category (ID, 41.1%, 4.2%; cerebral palsy, 37.5%, 4.8%; Down’s syndrome, 15.0%, 0%; severe motor and ID, 61.9%, 16.7%).
Anemia is an indicator of both poor nutrition and poor health (de Benoist et al., 2008). Many studies have indicated that severe anemia affects mental and physical development in children (Lozoff, 1989;
Lozoff et al., 1987; Lozoff, Jimenez, & Wolf, 1991). Although there were many studies that assessed the anemia provision for the general children in Taiwan (Shaou, Yi, & Pan, 1998; Wang & Shaou, 2006), the special group - people with ID, the anemia prevalence is unknown and associated risk factors have not been sufficiently studies. To provide the evidence-based information for assessing anemia is to inform stakeholders on the type of measures to be taken to prevent and control anemia, the present study aims to provide the information of anemia prevalence and its determinants of children and adolescents with ID in Taiwan.
2. Methods
A cross-sectional physical examination chart review was conducted in three special schools for children and adolescents with ID in 2008. The school age students accepted physical examination as they enrolled into schools at the first year, the examination includes body physical exam, biochemical among people with intellectual disabilities, but to prevent the problems become worst; the health authority should include providing children and adolescents with adequate nutrition and appropriate health protections during early childhood.
ß2009 Elsevier Ltd. All rights reserved.
(blood, urine and stool specimen) and X-ray checkup. The study was designed to include all eligible aged 6–18 years children and adolescents with ID from all three special schools. Ethics approval was received from all the study special schools.
There were 937 children and adolescents with ID who participated. We collected information on their demographic characteristics (age and gender), disability condition (type and level), BMI (weight and height) and measured blood hemoglobin concentration (Hb). Hb-the red, iron-containing chromoprotein within a circulating mature red blood cell that has the primary physiologic function of oxygen transport and also plays a role in carbon dioxide transport. Measurement of hemoglobin itself is a direct means of determining the presence of anemia, which is most frequently associated with iron deficiency (Hollowell et al., 2005). When iron-deficient erythropoiesis occurs, hemoglobin concentrations are reduced to below-optimal levels. As individual hemoglobin levels are below two standard deviations ( 2SD) of the distribution mean for hemoglobin in a normal population anemia is considered to be present (WHO, 2001). Anemia in the study was defined as Hb level below 13.0 g/dl in men, and 12.0 g/dl in women according to World Health Organization standards (Blanc et al., 1968). Data were analyzed with SPSS, version 14.0, a data analysis program. The number, percentage and chi-square method were used to describe the participant characteristics and analyzed their association with anemia. Multivariate analysis of logistic regression method, odds ratio (OR) and 95% confidence interval (95% CI) were used to evaluate the potential risk factors associated with anemia.
3. Results
The characteristics of study participants are reported in Table 1. Of the 937 children and adolescents with ID in this study, 559 were boys and 378 were girls, and the average age was 15.7
Table 1
Characteristics of study subjects.
Characteristics N % Mean SD (range)
Gender (N = 937)
Boys 559 59.7
Girls 378 40.3
Age (N = 937) 15.70 0.75 (6.0–18.0)
6–12 82 8.8
13–18 855 91.2
Disability type (N = 936)
ID 614 65.5
Multiplea 323 34.5
Disability level (N = 936)
Mild 81 8.7
Moderate 452 48.3
Severe 313 33.4
Profound 90 9.6
Height (N = 918) 155.30 14.21 (90.00–185.00)
Boys 548 159.74 13.31 (104.00–185.00)
Girls 371 148.76 12.92 (90.00–176.00)
Weight (N = 918) 53.04 18.06 (8.70–121.50)
Boys 548 56.04 18.77 (13.00–121.50)
Girls 371 48.62 15.99 (8.70–108.00)
BMI (kg/m2) (N = 916) 21.57 5.72 (8.67–50.41)
Underweight 274 29.9
Normal 314 34.3
Overweight 119 13.0
Obesity 209 22.8
aID accompanied with other disabilities.
years. 65.5% of the study participants were ID solely while 34.5% were ID accompanied with other disabilities (multiple disabilities) as well. In terms of disability level, most of the persons with ID in this study belonged to the moderate and severe level of disability (48.3% and 33.4%, respectively).
With regard to the physical figure of the participants, the results of a body mass index (BMI) analysis indicated that 34.3% were normal, 13.0% were overweight, 22.8% were obese and 29.9% were underweight.
Table 2 summarized the average Hb concentrations distribution of the study subjects. The Hb mean SD (g/dl) of the study participants was 14.06 1.58 (range = 6.00–18.70). Boys and girls were 14.85 1.21 (range = 7.70–18.70), 13.13 1.56 (range = 6.00–17.90), respectively. There were 11.6%
of children and adolescents with ID, who were anemic (boy <13 g/dl, girl <12 g/dl) in the study.
The Hb values were significantly increased by age in boys (p < 0.001), but were not increased in the girls (Fig. 1).
Table 3 analyzed Chi-square correlation between anemia and subject’s characteristics in the bivariant analysis. Gender, age, disability level and BMI are significantly correlated to anemia (p < 0.05). Girls (prevalence = 14.3%) were more inclining to be anemic than boys with ID (prevalence = 9.8%), and children of age 6–12 years (prevalence = 28.0%) were nearly three times more likely to be anemic than 13–18 year olds (prevalence = 10.1%). With regards to the disability level, we found the more severe the disability level is the more the possibility to be anemic in the study subjects. Finally, the body figure analyzed found different BMI will vary significantly on anemia prevalence in those children and adolescents with ID. Those underweight subjects were of significant higher prevalence in anemia than those subjects were normal, overweight or obese. The factor of disability type, ID solely or multiple disabilities was not significantly related to anemia prevalence in the subjects (p > 0.05).
The logistic regression model which evaluated the associated risk factors will determine the anemia occurrence by controlling the interaction of factors.Table 4shows that the factors of gender (OR = 0.63, 95% CI = 0.41–0.95), and age (OR = 3.21, 95% CI = 1.77–5.82) were the variables that can significantly predict whether they were anemic or not. Those children and adolescents with ID were Table 2
Hemoglobin concentration level of the study subjects (N = 937).
Characteristics N % Mean SD (range)
Hb concentration 14.06 1.58 (6.00–18.70)
Boys 559 59.7 14.85 1.21 (7.70–18.70)
Girls 378 40.3 13.13 1.56 (6.00–17.90)
Normala 828 88.4
Abnormalb 109 11.6
a Normal (non-anemia): boy >13g/dl, girl >12g/dl.
b Abnormal (anemia): boy 13g/dl, girl 12g/dl.
Fig. 1. Hemoglobin concentration at different age.
girls and those who were of younger age (6–12 years) were more likely to be anemic after controlling factors of disability type, disability level and BMI in the study.
4. Discussions
Anemia is known to be a significant public health problem in many countries. Iron deficiency anemia affects a significant part, and often a majority, of the population in nearly every country in the world (WHO, 2001). The present study found that the Hb concentration of the children and Table 3
Chi-square correlation between hemoglobin concentration and subject’s characteristics.
Characteristics N Hemoglobin concentration x2
Normal N (%) Abnormal N (%) (p-Value)
Gender 937 4.34
Boys 504 (90.2) 55 (9.8) (0.037)
Girls 324 (85.7) 54 (14.3)
Age 937 23.56
6–12 59 (72.0) 23 (28.0) (<0.001)
13–18 769 (89.9) 86 (10.1)
Disability type 937 2.53
ID 550 (89.6) 64 (10.4) (0.111)
Multiple 278 (86.1) 45 (13.9)
Disability level 936 5.19
Mild + moderate 482 (90.4) 51 (9.6) (0.023)
Severe + profound 345 (85.6) 58 (14.4)
BMI 916 6.74
Underweight 232 (84.7) 42 (15.3) (0.034)
Normal 278 (88.5) 36 (11.5)
Overweight/Obesity 300 (91.5) 28 (8.5)
Table 4
Logistic regression model for the association between anemia and subject’s characteristics (N = 915).
Variables b S.E. OR 95% CI p-Value
Constant 2.00 0.23 0.14 <0.001
Gender
Girls 1
Boys 0.47 0.21 0.63 0.41–0.95 0.027
Age
13–18 1
6–12 1.17 0.30 3.21 1.77–5.82 <0.001
Disability type
ID 1
Multiple 0.05 0.26 0.95 0.58–1.58 0.85
Disability level
Mild + moderate 1
Severe + profound 0.22 0.25 1.24 0.76–2.03 0.39
BMI
Normala 1
Underweight 0.27 0.25 1.30 0.80–2.14 0.29
Overweight/obesityb 0.28 0.27 0.76 0.45–1.28 0.30
aNormal (non-anemia): boy >13g/dl, girl >12g/dl.
b Abnormal (anemia): boy 13g/dl, girl 12g/dl.
adolescents with ID (6–18 years) was 14.06 g/dl, for boys and girls were 14.85 g/dl and 13.13 g/dl, respectively. According to the Taiwan Nutrition and Health Survey 1993–1996 we found that the mean of Hb in 7–12 years was 13.1 g/dl in boys and 12.7 g/dl in girls, and in those of 13–18 years was 14.5 g/dl in boys and 12.8 g/dl in girls (Shaou et al., 1998). The National Nutrition and Health of Primary School Students 2001–2002 (Wang & Shaou, 2006) found that the mean Hb values of children aged 6–12 years were 13.1 g/dl in boys and 13.0 g/dl in girls. It is difficult to assess the difference due to the difference in age groups among those studies. Comparing to the third National Health and Nutrition Examination Survey in US (NHANESIII) inTable 5, the mean Hb value in children and adolescents with ID was not significantly different from the general population of 6–14 years (Hollowell et al., 2005).
In total, 11.6% of children and adolescents with ID were anemic (boy <13 g/dl, girl <12 g/dl), and the gender, age, disability level and BMI are significantly correlated to anemia in bivariant analyses in the study. Comparing to national data in Taiwan,Wang and Shaou (2006)found that the prevalence of anemia Hb <11 g/dl for 6 years old and Hb <12 g/dl for 7–12 years old children was 11.4% in boys and 13.2% in girls in Taiwan. According toWHO (2001)suggested, in a normal population, 2.5% of the population would be expected to be below the 2SD thresholds. Hence, iron deficiency anemia would be considered a public health problem only when the prevalence of Hb concentration exceeds 5.0% of the population. It is needed to pay attention for the anemia prevalence of children and adolescents with ID in Taiwan.
Other studies, such as the overall anemia prevalence in school-aged children (5–15 years) was 13.6% in India, the boys (12.0%) had lower prevalence than girls (15.3%) (Muthayya et al., 2007).Wang, Ma, Xu, and Zou (2003)also found anemic prevalence among female high-school graduates was 11.3%, much higher than 1.5% of males in China.Wen et al. (2008)conducted a survey based on a standard medical screening programme and found that the anemia prevalence (Hb <13 g/dl in men and Hb
<12 g/dl in women) was 7.3% in adult population in Taiwan.Liu, Chang, and Lee (1994)who analyzed 2518 elderly people found that the age adjusted prevalence of anemia (Hb <12.5 g/dl in men and 11.5%
in women) was 6.5% in men and 8.3% in women. Prevalence rates increased significantly with age in women.
The present study also reveals that the factors of gender and age were significantly correlated to the occurrence of anemia in logistical regression model. In Japan, one study based on health checkup data found that factors related to an increase in anemia among adults with ID included gender (male), BMI, use of anticonvulsants or major tranquilizers, and a high zinc sulfate turbidity test value in a multivariate analysis (Ohwada et al., 2006). Not all demographic factors were associated with anemia.
A possible explanation for this observation is that the cut-off for hemoglobin values is based on WHO standards instead of ID individuals. The prevalence of anemia in a population is therefore a statistical Table 5
Mean hemoglobin by gender and age between the present study and the third National Health and Nutrition Examination Survey in US (NHANESIII)a.
Age Our data NHANESIII Test
N Mean (g/dl) SD N Mean (g/l)b SD t-Value
Boys 559
6–8 16 12.50 0.89 709 128.8 8.0 1.74
9–11 8 13.03 0.80 773 132.8 8.4 0.91
12–14 36 13.80 1.05 540 141.4 10.8 1.97
15–18 499 14.85 1.28 836c 150.7 10.3 4.03*
Girls 378
6–8 21 13.10 1.25 675 128.2 7.7 1.03
9–11 7 13.06 0.70 734 131.0 7.8 0.16
12–14 25 13.00 1.03 621 132.9 10.0 1.45
15–18 325 13.13 1.56 950c 131.5 10.0 0.27
a Hollowell et al. (2005).
b g/l=g/dl 10.
cAge group: 15–19.
* p< 0.001.
rather than a physiological concept (WHO, 2001). Most of the available information is incomplete or limited to special groups. Therefore, it is necessary to collect local data to evaluate the norms of Hb in the general population to assess the prevalence of anemia in the special groups.
The study highlights that the prevalence of anemia was 11.6% in children and adolescents with ID in Taiwan is regarded as a mild public health problem according to WHO standards (WHO, 2001). The efforts to prevent the problems become worst; the health authority should include providing children with adequate nutrition and appropriate health protections during early childhood.
Acknowledgements
This research was financially supported by the Bureau of Health Promotion, Ministry of Health, Taiwan (DOH97-HP-1601). We would also like to thank all the staff in the three special schools who support this study.
References
Beutler, E., & Waalen, J. (2006). The definition of anemia: What is the lower limit of normal of the blood hemoglobin concentration?
Blood, 107, 1747–1750.
Blanc, B., Finch, C. A., Hallberg, L., Lawkowicz, W., Layrisse, M., Mollin, D. L., et al. (1968). Nutritional anaemias. Report of a WHO Scientific Group. WHO Technical Report Series (vol. 405). pp. 1–40.
Dallman, P. R., Yip, R., & Johnson, C. (1984). Prevalence and causes of anemia in the United States, 1976–1980. The American Journal of Clinical Nutrition, 39, 437–445.
de Benoist, B., McLean, E., Egli, I., & Cogswell, M. (2008). Worldwide prevalence of anaemia 1993–2005: WHO global database on anaemia. Geneva: World Health Organization.
Hsu, S. W., Lin, Y. W., Chwo, M. J., Huang, H. C., Yen, C. F., Lin, L. P., et al. (2009). Emergency department utilization and determinants of use by 0 to 6-year-old children with disabilities in Taipei. Research in Developmental Disabilities, 30, 774–781.
Hollowell, J. G., Van Assendelft, O. W., Gunter, E. W., Lewis, B. G., Najjar, M., & Pfeiffer, C. (2005). Hematological and iron-related analytes—Reference data for persons aged 1 year and over: United States, 1988–1994. National Center for Health Statistics. Vital and Health Statistics, 11, 1–15.
Hurtado, E. K., Claussen, A. H., & Scott, K. G. (1999). Early childhood anemia and mild or moderate mental retardation. The American Journal of Clinical Nutrition, 69, 115–119.
Lin, J. D., Lee, T. N., Loh, C. H., Yen, C. F., Hsu, S. W., Wu, J. L., et al. (2009). Physical and mental health status of staff working for people with intellectual disabilities in Taiwan: Measurement with the 36-Item Short-Form (SF-36) health survey. Research in Developmental Disabilities, 30, 538–546.
Lin, J. D., Lin, Y. W., Yen, C. F., Loh, C. H., & Chwo, M. J. (2009). Received, understanding and satisfaction of National Health Insurance Premium Subsidy Scheme by families of children with disabilities: A census study in Taipei city. Research in Developmental Disabilities, 30, 275–283.
Lin, J. D., Loh, C. H., Choi, I. C., Yen, C. F., Hsu, S. W., Wu, J. L., et al. (2007). High outpatient visits among people with intellectual disabilities caring in a disability institution in Taipei: A 4-year survey. Research in Developmental Disabilities, 28, 84–93.
Lin, J. D., Wu, J. L., & Lee, P. N. (2004). Utilization of inpatient care and its determinants among persons with intellectual disabilities in day care institutions in Taiwan. Journal of Intellectual Disability Research, 48, 655–662.
Lin, J. D., Yen, C. F., Li, C. W., & Wu, J. L. (2005). Health, healthcare utilization and psychiatric disorder in people with intellectual disability in Taiwan. Journal of Intellectual Disability Research, 49, 86–94.
Lin, J. D., Yen, C. F., Loh, C. H., Hsu, S. W., Haung, H. C., Tang, C. C., et al. (2006). A cross-sectional study on the characteristics and determinants of emergency care utilization among people with intellectual disabilities in Taiwan. Research in Developmental Disabilities, 27, 657–667.
Liu, H. W., Chang, C. J., & Lee, J. Y. (1994). Epidemiological study in the elderly aged over 65 years in Taiwan. Kaohsiung Journal of Medical Science, 10, 683–688.
Lozoff, B. (1989). Methodologic issues in studying behavioral effects of infant iron-deficiency anemia. American Journal of Clinical Nutrition, 50(Suppl.), 641–654.
Lozoff, B., Brittenham, G. M., Wolf, A. W., McClish, D. K., Kuhnert, P. M., Jimenez, E., et al. (1987). Iron-deficiency anemia and iron therapy effects on infant developmental test performance. Pediatrics, 79, 981–995.
Lozoff, B., Jimenez, E., & Wolf, A. W. (1991). Long-term developmental outcome of infants with iron-deficiency. New England Journal of Medicine, 325, 687–694.
Muthayya, S., Thankachan, P., Zimmermann, M. B., Andersson, M., Eilander, A., Misquith, D., et al. (2007). Low anemia prevalence in school-aged children in Bangalore, South India: Possible effect of school health initiatives. European Journal of Clinical Nutrition, 61, 865–869.
Ohwada, H., Nakayama, T., Nara, N., Tomono, Y., & Yamanaka, K. (2006). An epidemiological study on anemia among institutionalized people with intellectual and/or motor disability with special reference to its frequency, severity and predictors. BMC Public Health, 6, 85–95.
Pavithran, K., & Raji, N. L. (2003). Aplastic anemia in Down’s syndrome. American Journal of Hematology, 73, 213.
Shaou, N. S., Yi, W. T., & Pan, W. H. (1998). Taiwan Nutrition and Health Survey, 1993–1996.http://food.doh.gov.tw/foodnew/Files/
Research/1993%20-%201996/12.pdf.
Wang, Z., Ma, A., Xu, D., & Zou, J. (2003). Comparison of hemoglobin level and anemia prevalence between female and male post- adolescent high school graduates. Journal of Hygiene Research, 32, 144–146 (in Chinese).
Wang, R. L., & Shaou, N. S. (2006). The national nutrition & health of primary school students, 2001–2002.http://food.doh.gov.tw/
foodnew/Files/Research/2001%20-%202002/I.pdf.
Wen, C. P., Cheng, T. Y. D., Tsai, M. K., Chang, Y. C., Chan, H. T., Tsai, S. P., et al. (2008). All-cause mortality attributable to chronic kidney disease: A prospective cohort study based on 462,293 adults in Taiwan. Lancet, 371, 2173–2182.
WHO. (2001). Iron deficiency anaemia assessment, prevention and control: A guide for programme managers. Geneva: World Health Organization. Series No.WHO/NHD/01.3.
Yen, C. F., Lin, J. D., Loh, C. H., Shi, L., & Hsu, S. W. (2009). Determinants of prescription drug use by adolescents with intellectual disabilities in Taiwan. Research in Developmental Disabilities, 30, 1354–1366.
