Elementary school performance of children with congenital hypothyroidism N e w England C o n g e n i t a l Hypothyroidism C o l l a b o r a t i v e * Hanover, New Hampshire The aim of this study was to determine whether hypothyroid children treated early as a result of diagnosis after n e o n a t a l screening progressed normally in school. The New England Congenital Hypothyroidism Collaborative studied 72 of its patients at the ages of 9 or 10 years after they had c o m p l e t e d 3 years of schooling b e y o n d kindergarten. Control subjects were 96 classmates of the same sex and a g e as the patients and 32 siblings of appropriate a g e for the testing. Intelligence quotients (IQs) were measured by the Wechsler Intelligence Scale for Children-Revised a b b r e v i a t e d to five items, and school a c h i e v e m e n t by the Peabody Individual A c h i e v e m e n t Test. In addition, a series of neuropsyc h o l o g i c tests was administered to both patients and control subjects. Educational histories were o b t a i n e d from the parents for 74 patients, 87 of their siblings, 96 classmates, a n d 96 siblings of the classmates. The IQ of the control subjects (mean _+ SEM) was 109 +_ 1.2 versus 106 _+ 1.4 for the patients. The mean overall a c h i e v e m e n t score was 109 _+ 0.93 for the control subjects and 108 _ 1.3 for the patients. These differences are not statistically significant. The regression lines relating overall P e a b o d y Individual A c h i e v e m e n t Test scores or subtests thereof to IQ did not differ a m o n g the patients and the control groups. Within the groups the regression lines for IQ and the different subtests of school a c h i e v e m e n t were also identical. The p e r c e n t a g e s of children repeating a grade, n e e d i n g extra tutoring, or in special classes were the same for patients and control groups. We c o n c l u d e that children with hypothyroidism have no a p p a r e n t specific impediments to learning unrelated to intelligence. (J PEDIATR1990;116:27-32)
We report the results of the third phase of a follow-up study of patients with infantile hypothyroidism diagnosed by neonatal hypothyroidism screening in New England. The first phase demonstrated that children who received early Supported by National Institute of Child Health and Human Development grant No. 2R01 HD 1959-06. Submitted for publication Feb. 28, 1989; accepted June 30, 1989. Reprint requests: Robert Z. Klein, MD, New England Congenital Hypothyroidism Collaborative, Department of Maternal and Child Health, Dartmouth Medical School, Hanover, NH 03756. *Members of the collaborative are M. B. Arnold, V. Bapat, Y. Baumgartner, A. Bennett, S. T. Biggs, H. H. Bode, S. Brink, J. Brown, R. Brown, D. Carey, T. Carpenter, C. Crawford, J. D. Crawford, J. E. Crigler, M. Danon, D. Frederick, M. Genel, P. Gruppuso, J. E. Haddow, J. Holmes, P. R. Larsen, J. Ma6Cracken, E. Man, M. L. Mitchell, J. M. Orson, L. A. Page, S. Ratzan, E. Reiter, W. Russell, A. Sadeghi-Nejad, B. Senior, W. Tamborlane, S. Waisbren, and R. Z. Klein (Coordinatoi'). 9/20/15040
treatment (at an average of 24 days of age) made possible by screening had normal Stanford-Binet intelligence quotient scores at 3 to 5 years of age. 1, 2 The mean and standard deviation for both patients and control subjects was 105 + 15, and the distribution of the individual scores was
ANOVA IQ PlAT T4 WISC-R
Analysis of variance Intelligence quotient Peabody Individual Achievement Test ThyrQxine Wechsler Intelligence Scale for ChildrenRevised
normal. The only factor relating significantly to IQ of the patients on multiple stepwise regression analyses was adequacy of treatment. The second phase showed that the mean Wechsler Intelligence Scale for Children-Revised ( W l S C R) score of the 57 oldest patients at 6 years of age was
27
28
Klein et al.
109 + 13; that of 59 control subjects was 110 _+ 13. 3 At that time a battery of neuropsychologic tests was administered and the patients differed from the control subjects in only one respect: their development of motor speed of small hand movements was slower. A few measurements in 7-year-old patients suggested that by that age the patients had caught up in speed in this test. The third phase was initiated to determine whether the patients progressed normally in school. The literature is replete with statements that even hypothyroid children with normal IQs cannot learn normally in school and that their progress in school is impeded by specific learning deficits or attention disorders. 47 We decided to study the children after at least 3 years of schooling beyond kindergarten. We believe that this period is a reasonable compromise because the later the testing is done, the more important environmental and psychologic factors are in determining school performance. Conversely, the earlier the testing, the less reliable are the measurement of school performance and the more influenced by social maturity. METHODS
The original patient cohort consisted of 144 infants with permanent hypothyroidism diagnosed in New England as a result of neonatal screening between January I, 1976, and December 31, 1980. During the first phase of the study five patients were excluded because of other conditions limiting testing or intelligence. Two had Down syndrome, one had Williams syndrome, and two had severe cerebral palsy with spastic quadriplegia. One child could not be tested because her family spoke only Spanish and she went to a school where Spanish was spoken. Three children who went to public schools were included, however, although their families spoke only Portuguese or Spanish. Two families refused permission for their children to be studied, and 12 families left the region or could not be found. When the testing at 6 years of age began, the Connecticut State Health Department removed 34 patients in that state from the study. By the third phase of the study, three more families could not be traced. One was found too late for the testing. Four families did not want their children to participate further. Of the remaining 83 patients, 11 had been born after October 1979 and were too young to have had 3 years of schooling beyond kindergarten. Thus 72 patients were studied with the tests listed below. In chi-square analyses these patients did not differ significantly from the original cohort in type of hypothyroidism (55% vs 43% with ectopic glandular tissue, 16% vs 22% with dyshormonogenesis, and 29% vs 35% with atrophic glands). There were also no differences in thyroxine concentration at the time of diagnosis (mean _ SEM 3.1 + 0.22 #g/dl [40 ___ 2.8 nmol/L] vs 3.1 + 0.29 #g/dl [40 _+ 3.7 nmol/L]) nor in the percentage of infants with bone age less than gestational age (53% vs
The Journal of Pediatrics January 1990
60%). The mean + SD Stanford-Binet IQ at 3 to 5 years of age'of patients in the third phase was 106 __+ 14 and that of the original cohort 105 + 15; the mean WISC-R IQ at 6 years of age was 109 _ 13 for the third-phase patients and 109 + 13 for the total cohort. The same studies were carried out in 96 classmate control subjects. They were the same sex and age as the patients and were all in the same classroom except three who were in another room in the same grade at the same school. There were two classmate control subjects for 41 patients, one for 14 patients, and none for 13 other patients who were nearly all residents of large inner-city areas. The control classmates were selected because the patients' parents felt most comfortable about either their or our approaching these children's parents. Thirty-two of the patients' euthyroid siblings of an appropriate age to be examined by the procedures also served as control subjects. Nine of the patients and their classmates were tested after completion of the fourth grade. Sixty-one patients and their classmates were tested after they finished the third grade. Two patients who had gone to "readiness class" after kindergarten were tested after the second grade. Four of the patients' siblings were tested after the fifth grade, l0 after the fourth, and 17 after the third. One sibling who repeated kindergarten was tested after the second grade. The parents supplied detailed educational histories for the 72 patients studied, as well as for the patient who was traced too late for testing and for one patient whose family was willing to give information but not to allow the patient to be tested. Educational histories were also obtained for the 96 classmate control subjects and for 96 of their siblings. The tests administered to the patients and the control subjects included the following: 1. WISC-R abbreviated to five items (vocabulary, block design, picture arrangement, information, and digit span) to limit length of overall testing; the correlation of this short form with the full W l S C - R is 0.958 2. Peabody Individual Achievement Test 3. Boston Naming Test 4. Kaufman Assessment of Children's Abilities: Gestalt Closure, Spatial Memory, and Logical Memory subtests 5. Peabody Picture Vocabulary Test 6. Automatized Series Test 7. Sentence Repetition Test 8. Achenbach Child Behavior Checklist 9. Sentence Completion Test 10. Beery Test of Visual-Motor Integration 11. Pegboard Performance Test 12. Marching Test 13. Finger Tapping 14. Timed Motor Tests 15. Informal Neurologic Examination of St~ressed Gaits
Volume 116
Hypothyroidism and school performance
29
Number 1
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Figure. Correlation of WISC-R scores and overall PIAT school achievement scores standardized for age. Patients (n = 72) are represented by solid circles and solid line. Equation for their regression line is y = 0.90x + 9.6; r 2 = 0.643. Control subjects (n = 127) are represented by open circles and dashed line. Their regressio n equation is y = 0.91x + 8.9; r 2 = 0.567.
Hollingshead Socioeconomic Rankings were also derived for the patients and their classmates. Statistical analyses were carried out on the Stat View 512+ program (Brain Power, lnc., Calabasas, Calif.) on a Macintosh computer. When the tests either were standardized adequately for age or were independent of age, the results for the patients were compared with the results for their classmates and siblings by t test and by analysis of variance. When the tests were neither independent of age nor adequately standardized for age, the results for the patients were compared only with resu!ts for the classmates by t test. The tests were administered by four psychometricians who did not know whether an examinee was patient, sibling, or classmate except in a handful of cases when a mother or child let slip a clue. Posttesting guesses by the examiners were correct no more often than would be expected by chance. RESULTS The mean age and grade of the patients and their classmates were identical; those for the siblings were a half year advanced. The differences between the siblings and patients or their classmates were statistically significant (p
We report the results of the third phase of a follow-up study of patients with infantile hypothyroidism diagnosed by neonatal hypothyroidism screening in New England. The first phase demonstrated that children who received early Supported by National Institute of Child Health and Human Development grant No. 2R01 HD 1959-06. Submitted for publication Feb. 28, 1989; accepted June 30, 1989. Reprint requests: Robert Z. Klein, MD, New England Congenital Hypothyroidism Collaborative, Department of Maternal and Child Health, Dartmouth Medical School, Hanover, NH 03756. *Members of the collaborative are M. B. Arnold, V. Bapat, Y. Baumgartner, A. Bennett, S. T. Biggs, H. H. Bode, S. Brink, J. Brown, R. Brown, D. Carey, T. Carpenter, C. Crawford, J. D. Crawford, J. E. Crigler, M. Danon, D. Frederick, M. Genel, P. Gruppuso, J. E. Haddow, J. Holmes, P. R. Larsen, J. Ma6Cracken, E. Man, M. L. Mitchell, J. M. Orson, L. A. Page, S. Ratzan, E. Reiter, W. Russell, A. Sadeghi-Nejad, B. Senior, W. Tamborlane, S. Waisbren, and R. Z. Klein (Coordinatoi'). 9/20/15040
treatment (at an average of 24 days of age) made possible by screening had normal Stanford-Binet intelligence quotient scores at 3 to 5 years of age. 1, 2 The mean and standard deviation for both patients and control subjects was 105 + 15, and the distribution of the individual scores was
ANOVA IQ PlAT T4 WISC-R
Analysis of variance Intelligence quotient Peabody Individual Achievement Test ThyrQxine Wechsler Intelligence Scale for ChildrenRevised
normal. The only factor relating significantly to IQ of the patients on multiple stepwise regression analyses was adequacy of treatment. The second phase showed that the mean Wechsler Intelligence Scale for Children-Revised ( W l S C R) score of the 57 oldest patients at 6 years of age was
27
28
Klein et al.
109 + 13; that of 59 control subjects was 110 _+ 13. 3 At that time a battery of neuropsychologic tests was administered and the patients differed from the control subjects in only one respect: their development of motor speed of small hand movements was slower. A few measurements in 7-year-old patients suggested that by that age the patients had caught up in speed in this test. The third phase was initiated to determine whether the patients progressed normally in school. The literature is replete with statements that even hypothyroid children with normal IQs cannot learn normally in school and that their progress in school is impeded by specific learning deficits or attention disorders. 47 We decided to study the children after at least 3 years of schooling beyond kindergarten. We believe that this period is a reasonable compromise because the later the testing is done, the more important environmental and psychologic factors are in determining school performance. Conversely, the earlier the testing, the less reliable are the measurement of school performance and the more influenced by social maturity. METHODS
The original patient cohort consisted of 144 infants with permanent hypothyroidism diagnosed in New England as a result of neonatal screening between January I, 1976, and December 31, 1980. During the first phase of the study five patients were excluded because of other conditions limiting testing or intelligence. Two had Down syndrome, one had Williams syndrome, and two had severe cerebral palsy with spastic quadriplegia. One child could not be tested because her family spoke only Spanish and she went to a school where Spanish was spoken. Three children who went to public schools were included, however, although their families spoke only Portuguese or Spanish. Two families refused permission for their children to be studied, and 12 families left the region or could not be found. When the testing at 6 years of age began, the Connecticut State Health Department removed 34 patients in that state from the study. By the third phase of the study, three more families could not be traced. One was found too late for the testing. Four families did not want their children to participate further. Of the remaining 83 patients, 11 had been born after October 1979 and were too young to have had 3 years of schooling beyond kindergarten. Thus 72 patients were studied with the tests listed below. In chi-square analyses these patients did not differ significantly from the original cohort in type of hypothyroidism (55% vs 43% with ectopic glandular tissue, 16% vs 22% with dyshormonogenesis, and 29% vs 35% with atrophic glands). There were also no differences in thyroxine concentration at the time of diagnosis (mean _ SEM 3.1 + 0.22 #g/dl [40 ___ 2.8 nmol/L] vs 3.1 + 0.29 #g/dl [40 _+ 3.7 nmol/L]) nor in the percentage of infants with bone age less than gestational age (53% vs
The Journal of Pediatrics January 1990
60%). The mean + SD Stanford-Binet IQ at 3 to 5 years of age'of patients in the third phase was 106 __+ 14 and that of the original cohort 105 + 15; the mean WISC-R IQ at 6 years of age was 109 _ 13 for the third-phase patients and 109 + 13 for the total cohort. The same studies were carried out in 96 classmate control subjects. They were the same sex and age as the patients and were all in the same classroom except three who were in another room in the same grade at the same school. There were two classmate control subjects for 41 patients, one for 14 patients, and none for 13 other patients who were nearly all residents of large inner-city areas. The control classmates were selected because the patients' parents felt most comfortable about either their or our approaching these children's parents. Thirty-two of the patients' euthyroid siblings of an appropriate age to be examined by the procedures also served as control subjects. Nine of the patients and their classmates were tested after completion of the fourth grade. Sixty-one patients and their classmates were tested after they finished the third grade. Two patients who had gone to "readiness class" after kindergarten were tested after the second grade. Four of the patients' siblings were tested after the fifth grade, l0 after the fourth, and 17 after the third. One sibling who repeated kindergarten was tested after the second grade. The parents supplied detailed educational histories for the 72 patients studied, as well as for the patient who was traced too late for testing and for one patient whose family was willing to give information but not to allow the patient to be tested. Educational histories were also obtained for the 96 classmate control subjects and for 96 of their siblings. The tests administered to the patients and the control subjects included the following: 1. WISC-R abbreviated to five items (vocabulary, block design, picture arrangement, information, and digit span) to limit length of overall testing; the correlation of this short form with the full W l S C - R is 0.958 2. Peabody Individual Achievement Test 3. Boston Naming Test 4. Kaufman Assessment of Children's Abilities: Gestalt Closure, Spatial Memory, and Logical Memory subtests 5. Peabody Picture Vocabulary Test 6. Automatized Series Test 7. Sentence Repetition Test 8. Achenbach Child Behavior Checklist 9. Sentence Completion Test 10. Beery Test of Visual-Motor Integration 11. Pegboard Performance Test 12. Marching Test 13. Finger Tapping 14. Timed Motor Tests 15. Informal Neurologic Examination of St~ressed Gaits
Volume 116
Hypothyroidism and school performance
29
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Figure. Correlation of WISC-R scores and overall PIAT school achievement scores standardized for age. Patients (n = 72) are represented by solid circles and solid line. Equation for their regression line is y = 0.90x + 9.6; r 2 = 0.643. Control subjects (n = 127) are represented by open circles and dashed line. Their regressio n equation is y = 0.91x + 8.9; r 2 = 0.567.
Hollingshead Socioeconomic Rankings were also derived for the patients and their classmates. Statistical analyses were carried out on the Stat View 512+ program (Brain Power, lnc., Calabasas, Calif.) on a Macintosh computer. When the tests either were standardized adequately for age or were independent of age, the results for the patients were compared with the results for their classmates and siblings by t test and by analysis of variance. When the tests were neither independent of age nor adequately standardized for age, the results for the patients were compared only with resu!ts for the classmates by t test. The tests were administered by four psychometricians who did not know whether an examinee was patient, sibling, or classmate except in a handful of cases when a mother or child let slip a clue. Posttesting guesses by the examiners were correct no more often than would be expected by chance. RESULTS The mean age and grade of the patients and their classmates were identical; those for the siblings were a half year advanced. The differences between the siblings and patients or their classmates were statistically significant (p
