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The cognitive outcome of very preterm infants may be poorer than often reported: An empirical investigation of how methodological issues make a big difference

European Journal of Pediatrics volume 153, pages 906–915 (1994)Cite this article

Abstract

The effects of relying on outmoded IQ-test norms and the use of arbitrary classifications of developmental delay on estimates of cognitive impairment of very preterm infants (VPI) was evaluated in a prospective population study. Cognitive assessments included the Griffiths test at 5 and 20 months and the Columbia Mental Maturity Scales (CMM) and a vocabulary test (Aktiver Wortschatz Test, AWST) at 56 months of age. Rates of cognitive impairment of 321 very preterm infants (VPI; <32 weeks gestation or <1500 g birth weight) were determined according to the published test norms, to scores of a full-term control group (FCn=321), and to scores from a representative sample of children (NCn=431) of the same birth cohort. IQ-scores were higher in the FC and NC children than in the original standardisation sample (SS). Using the concurrent test norms (FC, NC) up to 2.4 times more VPI were identified as seriously impaired (<−2 SD) than if the published (outdated) norms were used. Serious developmental delay was underestimated when arbitrary (e.g. DQ<70) rather than across age comparable definitions (DQ<−2 SD) were used. VPI study drop-outs had mothers with lower educational qualifications and poorer cognitive developmental scores at 5 or 20 months of age. In conclusion, a lack of appropriate control groups and use of arbitrary criteria for judging serious delay leads to large underestimations of cognitive impairment in VPI. Findings from previous uncontrolled studies of VPI need re-interpretation.

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Abbreviations

AWST :

Aktiver Wortschatz Test (vocabulary test)

CMM :

Columbia mental maturity scales

DQ :

developmental quotient

FC :

matched full-term controls

IQ :

intelligence quotient

NC :

normative representative controls

SS :

standard score (published norms in the test manuals)

SD :

standard deviation

VLBW :

very low birth weight

VPI :

very preterm infants (<32 weeks gestation or <1500 g at birth)

References

  1. Aylward GP (1988) Issues of prediction and developmental follow-up. J Dev Behav Pediatr 9: 107–109

    Google Scholar 

  2. Aylward GP, Hatcher RP, Stripp B, Gustafson NF, Leavitt LA (1985) Who goes and who stays: subject loss in a multicenter, longitudinal follow-up study. J Dev Behav Pediatr 6: 3–8

    Google Scholar 

  3. Aylward GP, Pfeiffer SI, Wright A, Verhulst SJ (1989) Outcome studies of low birth weight infants published in the last decade: a meta-analysis. J Pediatr 115: 515–520

    Google Scholar 

  4. Bauchner H, Brown E, Peskin J (1988) Premature graduates of the newborn intensive care unit: a guide to follow-up. Pediatr Clin N Amer 35: 1207–1225

    Google Scholar 

  5. Bayerische Landesärztekammer und Kassenärztliche Vereinigung Bayerns (1985) Bayerische Perinatal- und Neonatalerhebung 1985. BPE-Jahresbericht 1985. München

  6. Bayerisches Landesamt für Statistik und Datenverarbeitung (1986) Statistisches Jahrbuch 1985 für Bayern. München

  7. Bayley N (1969) Bayley Scales of infant development. Psychological Corporation. New York

    Google Scholar 

  8. Bill JM, Sykes DH, Hoy EA (1986) Difficulties in comparing outcomes of low-birthweight studies because of obsolescent test norms (annotation). Dev Med Child Neurol 28: 244–250

    Google Scholar 

  9. Bondy C, Cohen R, Eggert D, Lüer G (1975) Testbatterie für geistig behinderte Kinder. TBGB. Manual (3. rew. Aufl). Beltz Test, Weinheim

    Google Scholar 

  10. Brandt I (1983) Griffiths Entwicklungsskalen (GES) zur Beurteilung der Entwicklung in den ersten beiden Lebensjahren Beltz, Weinheim

    Google Scholar 

  11. Brooks-Gunn J, Gross RT, Kraemer HC, Spiker D, Shapiro S (1992) Enhancing the cognitive outcomes of low birth weight, premature infants. Pediatrics 89: 1209–1215

    Google Scholar 

  12. Brothwood M, Wolke D, Gamsu H, Cooper D (1988) Mortality, morbidity, growth and development of babies weighing 501–1000 grams and 1001–1500 grams at birth. Acta Paediatr Scand 77: 10–18

    Google Scholar 

  13. Burgemeister B, Blum L, Lorge J (1982) Columbia Mental Maturity Scale. Harcourt Brace Javanovich, New York

    Google Scholar 

  14. Campbell SK, Siegel E, Parr CA, Ramey CT (1986) Evidence for the need to renorm the Bayley Scales of infant development based on the performance of a population-hased sample of 12-month-old infants. Top Early Child Educ 6: 83–96

    Google Scholar 

  15. Clarke SCT, Nyberg V, Worth WH (1978) Technical report on Edmonton Grade III achievement: 1956–1977 comparisons. University of Alberta, Edmonton

    Google Scholar 

  16. Cohen RS, Stevenson DK, Malachowski N, Ariagno RL, Kimble KJ, Hopper AO, et al (1982) Favorable results of neonatal intensive care for very low-birth-weight infants. Pediatrics 69: 621–625

    Google Scholar 

  17. Collin MF, Halsey CL, Anderson CL (1991) Emerging developmental sequelae in the ‘normal’ extremely low birth weight infant. Pediatrics 88: 115–120

    Google Scholar 

  18. DeVries LS, Dubowitz LMS, Dubowitz V, Kaiser A, Lary S, Silverman M, et al (1985) Predictive value of cranial ultrasound in the newborn baby: a reappraisal. Lancet II: 137–140

    Google Scholar 

  19. Driscoll JM, Driscoll YT, Steir ME, Stark RI, Dangman BC, Perez A, et al (1982) Mortality and morbidity in infants less than 1001 grams birth weight. Pediatrics 69: 21–26

    Google Scholar 

  20. Dubowitz LM, Dubowitz V, Goldberg D (1970) Clinical assessment of gestational age in the newborn infant. J Pediatr 77: 1

    Google Scholar 

  21. Dunn LM (1981) Peabody Picture Vocabulary Test. American Guidance Service, Circle Pines, Minnesota

    Google Scholar 

  22. Eggert D (1972) Die Columbia Mental Maturity Scale als Individualtest für normalentwickelte Kinder im Alter von 3–10 Jahren. In: Eggert D (ed) Zur Diagnose der Minderbegabung. Beltz. Weinheim, pp 185–201

    Google Scholar 

  23. Escobar GJ, Littenberg B, Petitti DB (1991) Outcome among surviving very low birthweight infants: a meta analysis. Arch Dis Child 66: 204–211

    Google Scholar 

  24. Fawer CL, Diebold P, Calame A (1987) Periventricular leucomalacia and neurodevelopmental outcome in preterm infants. Arch Dis Child 62: 30–36

    Google Scholar 

  25. Flynn JR (1984) The mean IQ of Americans: massive gains 1932 to 1978. Psychol Bull 95: 29–51

    Google Scholar 

  26. Flynn JR (1986) Sociobiology and IQ trends over time. Behav Brain Sci 9: 192

    Google Scholar 

  27. Flynn JR (1987) Massive IQ gains in 14 nations: what IQ tests really measure. Psychol Bull 101: 171–191

    Google Scholar 

  28. Fuggle PW, Tokar S, Grant DB, Smith I (1992) Rising IQ scores in British children: recent evidence. J Child Psychol Psychiatry 33: 1241–1247

    Google Scholar 

  29. Griffiths R (1976) The abilities of babies: a study in mental measurement. Association for Research in Infant and Child Development, Amersham

    Google Scholar 

  30. Gross SJ, Oehler JM, Eckerman CO (1983) Head growth and developmental outcome in very low-birth-weight infants. Pediatrics 71: 70–75

    Google Scholar 

  31. Gross SJ, Slagle TA, D'Eugenio DB, Mettelman BB (1992) Impact of a matched term control group on interpretation of developmental performance in preterm infants. Pediatrics 90: 681–687

    Google Scholar 

  32. Halsey CL, Collin MF, Anderson CL (1993) Extremely low birth weight children and their peers: a comparison of preschool performance. Pediatrics 91: 807–810

    Google Scholar 

  33. Hanson R, Smith JA, Hume W (1985) Achievements of infants on items of the Griffiths scales: 1980 compared with 1950. Child Care Health Dev 11: 91–104

    Google Scholar 

  34. Heinonen KM (1989) Assessing the effectiveness of care for very low birth weight infants—do we really need population-based data? Pediatrics 84: 912–913

    Google Scholar 

  35. Holmes DL, Reich JN, Pasternak JF (1984) The development of infants born at risk. Lawrence Erlbaum Association, Hillsdale, New Jersey

    Google Scholar 

  36. Hoy EA, Bill JM, Sykes DH (1988) Very low birthweight: a long-term developmental impairment? Int J Behav Dev 11: 37–67

    Google Scholar 

  37. Hunt JV, Tooley WH, Harvin D (1982) Learning disabilities in children with birth weights 1500g. Semin Perinatol 6: 280–287

    Google Scholar 

  38. Johnson A, Townshend P, Yudkin P, Bull D, Wilkinson AR (1993) Functional abilities at age 4 years of children born before 29 weeks of gestation. BMJ 306: 1715–1718

    Google Scholar 

  39. Kiely JL, Paneth N (1981) Follow-up studies of very low-birth weight infants: suggestions for design, analysis and reporting. Dev Med Child Neurol 23: 96–99

    Google Scholar 

  40. Kiese C, Kozielski PM (1979) Aktiver Wortschatztes für drei- bis sechsjährige Kinder, AWST 3-6. Beltz Test. Weinheim

    Google Scholar 

  41. Kitchen WH, Doyle LW, Ford GW, Murton LJ, Keith CG, Rickards AL et al (1991) Changing two-year outcome of infants weighing 500 to 999 grams at birth: a hospital study. J Pediatr 118: 938–943

    Google Scholar 

  42. Kolb B, Wishaw IQ (1985) Fundamentals of human neuropsychology, WH Freeman, San Francisco

    Google Scholar 

  43. Kopp CB, McCall RB (1982) Predicting later mental performance for normal, at-risk, and handicapped infants. In: Baites PB, Brim OG, Jr (eds) Lifespan development and behavior, vol 4, Academic Press, San Diego, pp 33–60

    Google Scholar 

  44. Liaw F-R, Brooks-Gunn J (1993) Patterns of low birth weight children's cognitive development. Dev Psychol 29:1024–1035

    Google Scholar 

  45. Lloyd BW (1984) Outcome of verylow-birthweight babies from Wolverhampton. Lancet II: 739–741

    Google Scholar 

  46. Lucas A, Morley R, Cole TJ, Lister G, Leeson-Payne C (1982) Breast milk and subsequent intelligence quotient in children born pretern. Lancet 339: 261–264

    Google Scholar 

  47. Lynn R, Hampson SL, Mullineux JC (1987) A long term increase in the fluid intelligence of English children. Nature 328: 797

    Google Scholar 

  48. McCormick MC (1989) Long-term follow-up of infants discharged from neonatal intensive care units. J Am Med Assoc 261: 1767–1772

    Google Scholar 

  49. Murphy G (1987) Are intelligence tests outmoded? Arch Dis Child 62: 773–775

    Google Scholar 

  50. Mutch LMM, Johnson MA, Morley R (1989) Follow-up studies: design, organisation, and analysis. Arch Dis Child 64: 1394–1402

    Google Scholar 

  51. Orgill AA, Astbury J, Bajuk B, Yu VYH (1982) Early development of infants 1000 g or less at birth. Arch Dis Child 57: 823–827

    Google Scholar 

  52. Ornstein M, Ohlsson A, Edmonds J, Asztalos E (1991) Neonatal follow-up of very low birthweight/extremely low birthweight infants to school age: a critical overview Acta Paediatr Scand 80: 741–748

    Google Scholar 

  53. Palmer P, Dubowitz LMS, Levene MI, Dubowitz V (1982) Developmental and neurological progress of pretern infants with intraventricular haemorrhage and ventricular dilatation. Arch Dis Child 57: 748–753

    Google Scholar 

  54. Portnoy S, Callias M, Wolke D, Gamsu H (1988) Five-year follow-up study of extremely low-birthweight infants. Dev Med Child Neurol 30: 590–598

    Google Scholar 

  55. Ramsay M, Fitzhardinge PM (1977) A comparative study of two developmental scales: the Bayley and the Griffith. Early Human Develop 151–157

  56. Ramsay M, Piper MC (1980) A comparison of two developmental scales in evaluating infants with Down syndrome. Early Hum Dev 4: 89–95

    Google Scholar 

  57. Robertson CMT, Etches PC, Goldson E, Kyle JM (1992) Eight-year school performance, neurodevelopmental and growth outcome of neonates with bronchopulmonary dysplasia: a comparative study. Pediatrics 89: 365–372

    Google Scholar 

  58. Saigal S (1991) Follow-up of high risk infants methodological issues, current status, and future trends. In: Kiely M (ed) Reproductive and perinatal epidemiology. CRC Press, Inc., Boca Raton, Florida, pp 337–355

    Google Scholar 

  59. Skouteli HN, Dubowitz LMS, Levene MI, Miller G (1985) Predictors for survival and normal neurodevelopmental outcome of infants weighing less than 1001 grams at birth. Dev Med Child Neurol 27: 588–595

    Google Scholar 

  60. Skuse D, Wolke D, Reilly S (1992) Failure to thrive. Clinical and developmental aspects. In: Remschmidt H, Schmidt M (eds) Child and youth psychiatry. European perspectives, vol II: developmental psychopathology. Hans Huber, Stuttgart, pp 46–71

    Google Scholar 

  61. Skuse D, Pickles A, Wolke D, Reilly S (1994) Postnatal growth and mental development: evidence for a sensitive period. J Child Psychol Psychiatry 35: 521–545

    Google Scholar 

  62. Stewart AL, Reynolds EOR, Lipscomb AP (1981) Outcome for infants of very low birthweight: survey of world literature. Lancet I: 1038–1040

    Google Scholar 

  63. Stewart AL, Thorburn RJ, Hope PL, Goldsmith M, Lipscomb AP, Reynolds EOR (1983) Ultrasound appearance of the brain in very preterm infants and neurodevelopmental outcome at 18 months of age. Arch Dis Child 58: 598–604

    Google Scholar 

  64. Stewart AL, Costello AM deL, Hamilton PA, Baudin J, Townsend J, Bradford BC, et al (1989) Relationship between neurodevelopmental status of very preterm infants at one and four years. Dev Med Child Neurol 31: 756–765

    Google Scholar 

  65. Stjernqvist K, Svenningsen NW (1993) Extremely low-birth-weight infants less than 901 g. Growth and development after one year of life. Acta Paediatr 82: 40–44

    Google Scholar 

  66. Teasdale TW, Owen DR (1987) National secular trends in intelligence and education: a twenty-year cross-sectional study. Nature 325: 119–121

    Google Scholar 

  67. The fate of the baby under 1501 g at birth (editorial) (1980) Lancet I: 461

  68. Thompson CM, Buccimazza SS, Webster J, Malan AF, Molteno CD (1993) Infants of less than 1250 grams birth weight at Groote Schuur Hospital: outcome at 1 and 2 years of age. Pediatrics 5: 961–968

    Google Scholar 

  69. Thorburn RJ, Lipscomb AP, Stewart AL, Reynolds EOR, Hope PL, Pape KE (1981) Prediction of death and major handicap in very preterm infants by brain ultrasound. Lancet I: 1119–1121

    Google Scholar 

  70. Veen S, Ens-Dokkum MH, Schreuder AM, Verloove-Vanhorick SP, Brand R, Ruys JH (1991) Impairments, disabilities, and handicap of very preterm and very-low-birthweight infants at 5 years. Lancet 338: 33–36

    Google Scholar 

  71. Wariyar UK, Richmond S (1989) Morbidity and preterm delivery: importance of 100% follow-up. Lancet I: 387–388

    Google Scholar 

  72. Wolke D (1991) Supporting the development of low-birthweight infants (Annotation). J Child Psychol Psychiatry 32: 723–741

    Google Scholar 

  73. Wolke D (1993) Psychosoziale Entwicklung Frühgeborener: Was wir wissen und was wir wissen sollten. In: Lischka A, Bernert G (eds) Aktuelle Neuropädiatrie 1992. Ciba Geigy Wissenschaftlicher Verlag, Wehr, Baden, pp 99–121

    Google Scholar 

  74. Wolke D, Skuse D, Mathisen B (1990) Behavioral style in failure to thrive infants-a preliminary communication. J Pediatr Psychol 15: 237–254

    Google Scholar 

  75. Wolke D, Meyer R, Ohrt B, Riegel K (in press) The incidence of sleeping problems in preterm and fullterm infants discharged from neonatal special care units: an epidemiological longitudinal study. J Child Psychol Psychiatry

  76. Yu VYH, Downe L, Astbury J, Bajuk B (1986) Perinatal factors and adverse outcome in extremely low birthweight infants. Arch Dis Child 61: 554–558

    Google Scholar 

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Affiliations

  1. Bavarian Longitudinal Study II, University of Munich Children's Hospital, Lindwurmstrasse 4, D-80337, Munchen, Germany

    Dieter Wolke, Günter Ratschinski, Barbara Ohrt & Klaus Riegel

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  1. Dieter Wolke
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  2. Günter Ratschinski
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  3. Barbara Ohrt
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  4. Klaus Riegel
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Wolke, D., Ratschinski, G., Ohrt, B. et al. The cognitive outcome of very preterm infants may be poorer than often reported: An empirical investigation of how methodological issues make a big difference. Eur J Pediatr 153, 906–915 (1994). https://doi.org/10.1007/BF01954744

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Key words

  • VLBW
  • IQ
  • DQ Impairment
  • Drop-outs