/. biosoc. Sci. (1975) 7, 445^62
PHYSICAL GROWTH OF JAMAICAN SCHOOL CHILDREN WHO WERE SEVERELY MALNOURISHED BEFORE 2 YEARS OF AGE STEPHEN A. RICHARDSON Albert Einstein College of Medicine, New York (Received 2nd May 1975) Summary. A study is reported of physical growth of Jamaican schoolboys who had been admitted to hospital with severe malnutrition during infancy (index cases). Height, weight and head circumference of the index cases was - compared with that of male siblings close in age (siblings), with unrelated classmates or neighbours matched for sex and age (comparisons) and with Jamaican or US growth standards. Index boys were significantly smaller in height and head circumference than comparisons and significantly smaller than sibs only in head circumference. Sibs were intermediate in stature to the index and comparison boys. When the boys were divided into three age groups there was evidence of complete catch-up in height and weight after 7 years of age, but catch-up was incomplete for head circumference in the oldest group. No significant differences in stature at follow-up of the index boys were found in relation to age when admitted to hospital. Introduction
The purpose of this paper is to determine (1) whether Jamaican boys who were admitted to hospital with marasmus and kwashiorkor in the first 2 years of life are later stunted in growth and to what extent there is evidence of 'catch-up' in growth, and (2) to investigate whether there are critical periods during infancy when severe malnutrition has more serious consequences for later growth than at other ages. Previous studies have differed as to whether the children used for comparison at follow-up were or were not siblings of the malnourished children. Three studies have used siblings as comparisons (Keet et ah, 1971; Graham, 1972; Garrow & Pike, 1967). The rationale is that apart from the period in hospital due to severe malnutrition, siblings are more likely than non-siblings to have experienced similar biological and social histories including general level of nutrition. In general these studies do not show the children who were severely malnourished in infancy to be smaller than their siblings; the one exception (Keet et al., 1971) was for girls to be shorter. 445
446
Stephen A. Richardson
A large number of studies have used non-siblings as comparisons (Hoorweg & Stanfield, 1972; Krueger, 1969; Chase & Martin, 1970; Stoch & Smythe, 1967; Champakam, Srikantia & Gopalan, 1968; Cabak & Najdanvik, 1965). Only Champakam et al. (1968) and Cabak & Najdanvik (1965) did not show that the malnourished children were significantly smaller than the comparisons. The design of these studies makes it difficult to interpret what role severe malnutrition played in the growth of the children. The authors used the term 'controls' for the comparisons who were not admitted to hospital for severe malnutrition. These 'controls' were matched with the malnourished children on variables such as age, sex, socio-economic status, community and class at school. It is most unlikely that this matching does control on all factors which may affect growth, such as overall nutritional histories, infections, infestations, genetic factors, birth order, disturbances in the mother-child relationship, social and emotional disturbances associated with an infant's failure to thrive and inadequate physical stimulation. Chronic malnutrition may lead to depressed physical activity, apathy and loss of curiosity and reduced demands of the infant on the mother. If the malnutrition is inter-generational, the mother may have experienced stunting of growth and may have provided a poor intrauterine environment for the fetal growth of her children. A stay in hospital involves social and biological changes which may have long-term consequences; these may be beneficial or harmful, depending on the general ecology of the hospital as compared with the home. The extent to which each of these factors in various combinations affects growth is still largely unknown but they are not controlled for in any of the studies reviewed, nor have they been considered from a multivariate or ecological viewpoint. The widespread use of the term 'controls' and the loose experimental designs have led to the research issue being posed as, 'Does severe malnutrition in infancy cause stunting in growth and functional impairment ?' Perhaps the more meaningful research issue, is 'Under what circumstances and conditions do different forms of malnutrition have differing effects on physical growth and functional development ?' In the studies referred to, statistical criteria have been used to judge the significance of differences in stature between the children who were and were not admitted to hospital with severe malnutrition. Where differences were found, there has been little discussion of whether these differences have biological, functional or social significance for the children. The following tentative generalizations may be drawn from previous research: First, where the histories of the severely malnourished child and the comparison child suggest a similar level of nutrition over their life histories, except for the presence or absence of an acute episode requiring a stay in hospital, and where both sets of children have experienced similar general social, physical and biological environments, the children with the acute episode of malnutrition will not be smaller in somatic measures than their comparisons.
Malnutrition and physical growth
447
Second, where the children with an early acute episode of malnutrition are more disadvantaged than their comparisons in their overall histories of nutrition, social, physical and biological environments, then the malnourished children, at school age, will be smaller in somatic growth than their comparisons. 'Catch-up1 after severe malnutrition Whether or not full catch-up occurs during the years following marasmus or kwashiorkor in infancy, it is important to know the rates of catch-up at different ages. This information is needed for interpreting the results of follow-up studies done at different age levels and for suggesting times when the nutritional needs of the child require special attention. After an episode of severe malnutrition, rapid catch-up in growth occurs during the convalescent period if the calorific intake is sufficiently high and then slower recovery continues for a year or two (Garrow & Pike, 1967; Ashworth et al, 1968; Ashworth, 1969; Suckling & Campbell, 1957; McWilliam & Dean, 1965). For older children of school age there is no clear evidence of continued catch-up. Age at time of severe malnutrition It has been suggested that when severe malnutrition occurs during the time of most rapid brain growth, central nervous system damage is more likely to occur than if malnutrition is experienced during the period of life when the brain is growing less rapidly (Davison & Dobbing, 1966; Dobbing, 1964; Winick & Noble, 1966; Winick, 1968). Brain growth in humans, as measured by increments in fresh weight, occurs most rapidly during the first 6 months of life (Dobbing, 1968). The suggestion has been made that the programme for somatic growth is located in the brain. If severe malnutrition during the period of maximum brain growth impairs this programme then children who were severely malnourished in the first 6 months of life may later be smaller than those where malnutrition occurred after the first 6 months. Studies which have followed-up children over 4 years of age who were in hospital at different ages have not found significant differences in height, weight or head circumference (Keet et ah, 1971; Hoorweg & Stanfield, 1972; Chase & Martin, 1970). Study design and methods
The malnourished children selected for study are 74 boys (index cases) who had been admitted to hospital with a primary diagnosis of marasmus or kwashiorkor during their first 2 years of life. They had been treated in the metabolic ward of the Tropical Metabolism Research Unit (TMRU), of the Medical Research Council or the paediatric ward of the University of the West Indies, Mona, Kingston, Jamaica. They were selected for the study so that the ages at which they were admitted to hospital were distributed from less than 6 months to 24
448
Stephen A. Richardson
months. They received an average of 8 weeks of hospital care, and were followed-up as outpatients by social workers and public health nurses for 2 years. At the time of the present follow-up study the boys ranged in age from 6 to 11 years. Only males were used in the study because boys were predominantly selected for treatment at the TMRU. Approximately half of the index boys lived in the environs of the City of Kingston and the remainder in other smaller towns, villages and rural areas. Only two of the children from the TMRU could not be traced. Two other children were traced but not included in the study because one had Down's syndrome and the other had infantile hemiplegia, probably of perinatal origin. To study the physical growth of the index boys and of peers who had not been in hospital for severe malnutrition, three comparisons were made. A sibling of each index case was selected if the following criteria were met: male, between 6 and 12 years of age, with no history of treatment in hospital for severe malnutrition. If more than one sibling met the requirements, the boy closest in age to the index boy was chosen. Because of the widely varying patterns of family composition in Jamaica, a sib was defined as a child having the same biological mother as the index child and having shared the home residence with the index child for most of his life. Fifty-one per cent of the index boys had such sibs and these were all studied. Because of the age criterion used, sibs tended to be older than index cases. Non-sib comparisons were also made. For those index children attending school, two classmates of the same sex and within 6 months of age of the index child were selected. If the comparison nearer in age was not available for examination, the second comparison was used. Some of the index boys, though of school age, were not attending school and some attended small schools where no classmate met the study requirements. For these cases, a comparison was chosen by finding the nearest boy in the neighbourhood of the index boy's home who was not a relative and who was within 6 months of age of the index boy. Appropriate non-sib comparisons could not be found for three of the malnourished boys. Of the 71 comparison cases, 58 were classmates and thirteen were neighbours (all hereafter called comparisons). Of the index-comparison matched pairs the ages were within 1 month for 36 pairs, the index boys were older for eighteen pairs, and younger for seventeen pairs. The boys were predominantly of African descent. A more detailed statement of the study population and its selection is given by Hertzig et al. (1972). The third comparison examined the index boys in relation to Jamaican and American standards. The heights, weights and head circumferences of the index, sibs and comparisons were measured at the TMRU at the time of the follow-up study. Measurements were made by physicians who followed a standardized procedure; they were not told to which group the subjects belonged. Height was obtained in a standing position without shoes against a vertical measuring rod. Boys were weighed in trousers alone on a balance calibrated to an accuracy of 1 oz. Head circumference was measured by tape using standard reference points
Malnutrition and physical growth
449
of occiput and glabella. (One index boy was not measured for head circumference.) Heights and weights were also obtained by public health nurses. Correlations between the doctor and nurse sets of independent measurements range from 0-88 to 0-97. In reporting results, the physician measures are used. Actual measures are used when comparing index boys and their comparisons because of the close matching for age. Measurements were converted to standard scores for comparing index boys and their siblings because of age differences. Standard scores for heights and weights were based on standards developed for Jamaican primary school boys 7 years and older (Ashcroft & Lovell, 1966) and for rural Jamaican boys under 7 years (Ashcroft, Lovell & Williams, 1965). These standards were derived from boys living mostly in lower income families. Head circumference standard scores were based on the standards for boys in the US (Vickers & Stuart, 1943), as no standards for this measure were available for Jamaica. In all cases for standard scores the mean is zero and the standard deviation one. Results The index boys are smaller than their matched comparisons on height, weight and head circumference (Table 1). The differences are statistically significant for height and head circumference, but not for weight. To show the individual measures on height and weight all 74 index boys and the 71 comparisons are plotted by age on graphs (Text-figs. 1 and 2) which include the 10th, 50th and 90th percentiles derived from the surveys of Jamaican boys by Ashcroft and his co-workers (1965, Table 1. Differences between index boys and matched comparisons in height, weight and head circumference*
Somatic measure Height (in.) Indexf Comparison! Weight (lb) Indext Comparison! Head circumference (cm) Indexf Comparisonf
Mean
Matched t
One-tail level of probability
47-41 48-53
307
PHYSICAL GROWTH OF JAMAICAN SCHOOL CHILDREN WHO WERE SEVERELY MALNOURISHED BEFORE 2 YEARS OF AGE STEPHEN A. RICHARDSON Albert Einstein College of Medicine, New York (Received 2nd May 1975) Summary. A study is reported of physical growth of Jamaican schoolboys who had been admitted to hospital with severe malnutrition during infancy (index cases). Height, weight and head circumference of the index cases was - compared with that of male siblings close in age (siblings), with unrelated classmates or neighbours matched for sex and age (comparisons) and with Jamaican or US growth standards. Index boys were significantly smaller in height and head circumference than comparisons and significantly smaller than sibs only in head circumference. Sibs were intermediate in stature to the index and comparison boys. When the boys were divided into three age groups there was evidence of complete catch-up in height and weight after 7 years of age, but catch-up was incomplete for head circumference in the oldest group. No significant differences in stature at follow-up of the index boys were found in relation to age when admitted to hospital. Introduction
The purpose of this paper is to determine (1) whether Jamaican boys who were admitted to hospital with marasmus and kwashiorkor in the first 2 years of life are later stunted in growth and to what extent there is evidence of 'catch-up' in growth, and (2) to investigate whether there are critical periods during infancy when severe malnutrition has more serious consequences for later growth than at other ages. Previous studies have differed as to whether the children used for comparison at follow-up were or were not siblings of the malnourished children. Three studies have used siblings as comparisons (Keet et ah, 1971; Graham, 1972; Garrow & Pike, 1967). The rationale is that apart from the period in hospital due to severe malnutrition, siblings are more likely than non-siblings to have experienced similar biological and social histories including general level of nutrition. In general these studies do not show the children who were severely malnourished in infancy to be smaller than their siblings; the one exception (Keet et al., 1971) was for girls to be shorter. 445
446
Stephen A. Richardson
A large number of studies have used non-siblings as comparisons (Hoorweg & Stanfield, 1972; Krueger, 1969; Chase & Martin, 1970; Stoch & Smythe, 1967; Champakam, Srikantia & Gopalan, 1968; Cabak & Najdanvik, 1965). Only Champakam et al. (1968) and Cabak & Najdanvik (1965) did not show that the malnourished children were significantly smaller than the comparisons. The design of these studies makes it difficult to interpret what role severe malnutrition played in the growth of the children. The authors used the term 'controls' for the comparisons who were not admitted to hospital for severe malnutrition. These 'controls' were matched with the malnourished children on variables such as age, sex, socio-economic status, community and class at school. It is most unlikely that this matching does control on all factors which may affect growth, such as overall nutritional histories, infections, infestations, genetic factors, birth order, disturbances in the mother-child relationship, social and emotional disturbances associated with an infant's failure to thrive and inadequate physical stimulation. Chronic malnutrition may lead to depressed physical activity, apathy and loss of curiosity and reduced demands of the infant on the mother. If the malnutrition is inter-generational, the mother may have experienced stunting of growth and may have provided a poor intrauterine environment for the fetal growth of her children. A stay in hospital involves social and biological changes which may have long-term consequences; these may be beneficial or harmful, depending on the general ecology of the hospital as compared with the home. The extent to which each of these factors in various combinations affects growth is still largely unknown but they are not controlled for in any of the studies reviewed, nor have they been considered from a multivariate or ecological viewpoint. The widespread use of the term 'controls' and the loose experimental designs have led to the research issue being posed as, 'Does severe malnutrition in infancy cause stunting in growth and functional impairment ?' Perhaps the more meaningful research issue, is 'Under what circumstances and conditions do different forms of malnutrition have differing effects on physical growth and functional development ?' In the studies referred to, statistical criteria have been used to judge the significance of differences in stature between the children who were and were not admitted to hospital with severe malnutrition. Where differences were found, there has been little discussion of whether these differences have biological, functional or social significance for the children. The following tentative generalizations may be drawn from previous research: First, where the histories of the severely malnourished child and the comparison child suggest a similar level of nutrition over their life histories, except for the presence or absence of an acute episode requiring a stay in hospital, and where both sets of children have experienced similar general social, physical and biological environments, the children with the acute episode of malnutrition will not be smaller in somatic measures than their comparisons.
Malnutrition and physical growth
447
Second, where the children with an early acute episode of malnutrition are more disadvantaged than their comparisons in their overall histories of nutrition, social, physical and biological environments, then the malnourished children, at school age, will be smaller in somatic growth than their comparisons. 'Catch-up1 after severe malnutrition Whether or not full catch-up occurs during the years following marasmus or kwashiorkor in infancy, it is important to know the rates of catch-up at different ages. This information is needed for interpreting the results of follow-up studies done at different age levels and for suggesting times when the nutritional needs of the child require special attention. After an episode of severe malnutrition, rapid catch-up in growth occurs during the convalescent period if the calorific intake is sufficiently high and then slower recovery continues for a year or two (Garrow & Pike, 1967; Ashworth et al, 1968; Ashworth, 1969; Suckling & Campbell, 1957; McWilliam & Dean, 1965). For older children of school age there is no clear evidence of continued catch-up. Age at time of severe malnutrition It has been suggested that when severe malnutrition occurs during the time of most rapid brain growth, central nervous system damage is more likely to occur than if malnutrition is experienced during the period of life when the brain is growing less rapidly (Davison & Dobbing, 1966; Dobbing, 1964; Winick & Noble, 1966; Winick, 1968). Brain growth in humans, as measured by increments in fresh weight, occurs most rapidly during the first 6 months of life (Dobbing, 1968). The suggestion has been made that the programme for somatic growth is located in the brain. If severe malnutrition during the period of maximum brain growth impairs this programme then children who were severely malnourished in the first 6 months of life may later be smaller than those where malnutrition occurred after the first 6 months. Studies which have followed-up children over 4 years of age who were in hospital at different ages have not found significant differences in height, weight or head circumference (Keet et ah, 1971; Hoorweg & Stanfield, 1972; Chase & Martin, 1970). Study design and methods
The malnourished children selected for study are 74 boys (index cases) who had been admitted to hospital with a primary diagnosis of marasmus or kwashiorkor during their first 2 years of life. They had been treated in the metabolic ward of the Tropical Metabolism Research Unit (TMRU), of the Medical Research Council or the paediatric ward of the University of the West Indies, Mona, Kingston, Jamaica. They were selected for the study so that the ages at which they were admitted to hospital were distributed from less than 6 months to 24
448
Stephen A. Richardson
months. They received an average of 8 weeks of hospital care, and were followed-up as outpatients by social workers and public health nurses for 2 years. At the time of the present follow-up study the boys ranged in age from 6 to 11 years. Only males were used in the study because boys were predominantly selected for treatment at the TMRU. Approximately half of the index boys lived in the environs of the City of Kingston and the remainder in other smaller towns, villages and rural areas. Only two of the children from the TMRU could not be traced. Two other children were traced but not included in the study because one had Down's syndrome and the other had infantile hemiplegia, probably of perinatal origin. To study the physical growth of the index boys and of peers who had not been in hospital for severe malnutrition, three comparisons were made. A sibling of each index case was selected if the following criteria were met: male, between 6 and 12 years of age, with no history of treatment in hospital for severe malnutrition. If more than one sibling met the requirements, the boy closest in age to the index boy was chosen. Because of the widely varying patterns of family composition in Jamaica, a sib was defined as a child having the same biological mother as the index child and having shared the home residence with the index child for most of his life. Fifty-one per cent of the index boys had such sibs and these were all studied. Because of the age criterion used, sibs tended to be older than index cases. Non-sib comparisons were also made. For those index children attending school, two classmates of the same sex and within 6 months of age of the index child were selected. If the comparison nearer in age was not available for examination, the second comparison was used. Some of the index boys, though of school age, were not attending school and some attended small schools where no classmate met the study requirements. For these cases, a comparison was chosen by finding the nearest boy in the neighbourhood of the index boy's home who was not a relative and who was within 6 months of age of the index boy. Appropriate non-sib comparisons could not be found for three of the malnourished boys. Of the 71 comparison cases, 58 were classmates and thirteen were neighbours (all hereafter called comparisons). Of the index-comparison matched pairs the ages were within 1 month for 36 pairs, the index boys were older for eighteen pairs, and younger for seventeen pairs. The boys were predominantly of African descent. A more detailed statement of the study population and its selection is given by Hertzig et al. (1972). The third comparison examined the index boys in relation to Jamaican and American standards. The heights, weights and head circumferences of the index, sibs and comparisons were measured at the TMRU at the time of the follow-up study. Measurements were made by physicians who followed a standardized procedure; they were not told to which group the subjects belonged. Height was obtained in a standing position without shoes against a vertical measuring rod. Boys were weighed in trousers alone on a balance calibrated to an accuracy of 1 oz. Head circumference was measured by tape using standard reference points
Malnutrition and physical growth
449
of occiput and glabella. (One index boy was not measured for head circumference.) Heights and weights were also obtained by public health nurses. Correlations between the doctor and nurse sets of independent measurements range from 0-88 to 0-97. In reporting results, the physician measures are used. Actual measures are used when comparing index boys and their comparisons because of the close matching for age. Measurements were converted to standard scores for comparing index boys and their siblings because of age differences. Standard scores for heights and weights were based on standards developed for Jamaican primary school boys 7 years and older (Ashcroft & Lovell, 1966) and for rural Jamaican boys under 7 years (Ashcroft, Lovell & Williams, 1965). These standards were derived from boys living mostly in lower income families. Head circumference standard scores were based on the standards for boys in the US (Vickers & Stuart, 1943), as no standards for this measure were available for Jamaica. In all cases for standard scores the mean is zero and the standard deviation one. Results The index boys are smaller than their matched comparisons on height, weight and head circumference (Table 1). The differences are statistically significant for height and head circumference, but not for weight. To show the individual measures on height and weight all 74 index boys and the 71 comparisons are plotted by age on graphs (Text-figs. 1 and 2) which include the 10th, 50th and 90th percentiles derived from the surveys of Jamaican boys by Ashcroft and his co-workers (1965, Table 1. Differences between index boys and matched comparisons in height, weight and head circumference*
Somatic measure Height (in.) Indexf Comparison! Weight (lb) Indext Comparison! Head circumference (cm) Indexf Comparisonf
Mean
Matched t
One-tail level of probability
47-41 48-53
307
