Neurocognitive, Functional, and Health Outcomes at 5 Years of Age for Children After Complex Cardiac Surgery at 6 Weeks of Age or Younger
OBJECTIVE. This work provides neurocognitive, functional, and health outcomes for 5-year survivors of early infant complex cardiac surgery, including those with chromosomal abnormalities.
PATIENTS AND METHODS. Of 85 children (22.4% mortality), 61 received multidisciplinary, individual evaluation and parental questionnaires at 5 years. Full-scale, verbal, and performance IQ scores were compared by using analysis of variance among children who received different surgeries (arterial switch, 20; Norwood for hypoplastic left heart syndrome, 14; simple total anomalous pulmonary venous connection, 6; miscellaneous, 21; and chromosomal abnormalities, 8). Predictions from mental scores at 2 years for IQ scores at 5 years were determined.
RESULTS. Children with chromosomal abnormalities had lower full-scale and verbal IQs at 5 years than other survivors, with no differences found among the remaining groups. For children post-Norwood, performance IQ scores remained lower than for children after the arterial-switch operation. Prediction of full-scale IQ (<70) from 2-year mental scores for all 61 children were as follows: sensitivity, 87.5%; specificity, 88.1%; positive predictive value, 53.8%; and negative predictive value, 97.9%. For full-scale IQ of <85, predictions were 90.0%, 87.8%, 78.3%, and 94.7%, respectively. For those 53 without chromosomal abnormalities, full-scale IQ <70, respective predictions were 86.7%, 90.0%, 28.6%, and 97.8%, and for full-scale IQ <85, respective predictions were 85.7%, 89.7%, 75.0%, and 94.6%. Parental report indicated good health in 80% and adequate function in 67% to 88% of the children, although health-utilization numbers suggest that these reports are optimistic.
CONCLUSIONS. Five-year full-scale and verbal IQs were similar among groups, excluding those with chromosomal abnormalities. Children with chromosomal abnormalities had the lowest scores. Excluding those with chromosomal abnormalities, the mean mental scores for the children as a group tended to increase from 2 to 5 years of age, with an overall high percentage of correct classifications at 2 years.
There is concern about childhood health, neurocognitive, neuromotor, and functional outcomes for the increasing number of survivors after neonatal complex cardiac surgery.1–3 These outcomes have been explored after specific types of surgical repairs4–18 and for various procedures reported as whole-group outcomes.19–22 A pattern of normal to near-normal verbal skills but lower performance, motor, and visual-motor integration skills is emerging among many survivors.4–6,8,9,12,13,15,21 Identification of children needing early neurodevelopmental intervention and education has been stressed.2,20,23 However, there have been few longitudinal studies and, thus far, only modest identification of school-age learning deficits.23 Parental questionnaires suggest that the children have overall good health.11,14,15,24 Functional outcomes have been reassuring,7,10,11,14 but there are concerns about daily living and socialization skills.20 Many studies have either not indicated or excluded children with known chromosomal abnormalities.4,5,13,19–21,23 When identified, children with genetic abnormalities have lower developmental scores than other survivors after early complex cardiac surgery.22,25–27
In our previous publication, we related early neurodevelopmental outcome after neonatal complex cardiac surgery to demographic, perioperative, and operative measures.22 We demonstrated the importance of the preoperative condition to outcome.22 This article describes neurocognitive, functional, and health outcomes at school entry for this same cohort. We chose standardized neurocognitive measures as a major outcome given their association with areas of concern for these survivors, including skills of daily living, socialization, and school performance. Early childhood assessment has been reported to have poor validity for later problems.3 We wish to clarify the relationship between the 2-year standardized mental scores and the 5-year intelligence scores.
PATIENTS AND METHODS
This was a longitudinal study of an inception cohort as described previously.22 All 85 of the consecutive infants with complex cardiac surgery at ≤6 weeks of age completed at the Stollery Children's Hospital from September 1996 through August 1999 were enrolled. Children were from and follow-up assessments were conducted at 5 centers in 3 provinces: Calgary and Edmonton, Alberta; Regina and Saskatoon, Saskatchewan; and Winnipeg, Manitoba. At inception, the group of 85 children was composed of 58 boys (68%), 69 (81%) were white, and 75 (88%) had birth weight >2500 g. Primary cardiac diagnoses included transposition of the great arteries in 23, hypoplastic left heart syndrome in 26, truncus arteriosus in 9, simple total anomalous pulmonary venous connection in 6, complex anomalies involving the aortic arch in 14, mitral valves in 2, other single ventricle in 2, and other in 3. Eleven children with chromosomal anomalies were included. Genetic consultations were obtained antenatally with suspected major congenital heart disease and routinely for neonates with dysmorphic features or conotruncal lesions. Ongoing genetic consultations were made at the neurodevelopmental pediatrician's discretion. Diagnoses were confirmed by karyotype and DNA or fluorescent in situ hybridization. Seven children had the initial surgery after 28 days of life.
The method of enrollment, surgeries performed, data collection, and outcomes to age 2 years have been described previously.22 Socioeconomic status was determined using the Blishen index, with a population mean (SD) of 43 (13).28 Maternal education was indicated by years of schooling. Race was coded according to National Institutes of Health specifications.29 Ethics board approvals were obtained before initiation of the study, and informed consent was obtained from all of the parents or guardians.
Assessment at 5 Years
Multidisciplinary assessments and parent-completed questionnaires and interviews were conducted on 62 of 66 survivors at a mean (SD) of 60 (9) months of age. Data from 1 child, diagnosed with autism, were not included in the analysis, leaving 61 children in this report. Pediatricians, experienced in neurodevelopmental follow-up, provided information on neuromotor and sensory impairments: cerebral palsy (Bax30), visual impairment (corrected visual acuity in the better eye < 20/60), or sensorineural hearing loss (minimal response of >25 dB of hearing loss at any frequency from 250 to 4000 Hz in the better-hearing ear as tested by certified pediatric audiologists in sound booths). Current age-appropriate standardized testing by experienced pediatric psychologists or psychometrists included the Wechsler Preschool and Primary Scale of Intelligence revised edition (WPPSI-R)31 or third edition (WPPSI-III)32 and the Beery Visual Motor Integration Test (VMI).33 Variables included the US normed full-scale IQ (FSIQ), verbal IQ (VIQ), performance IQ (PIQ), and VMI. IQs from the WPPSI-R31 and WPPSI-III32 show correlations of 0.85 (FSIQ), 0.86 (VIQ), and 0.70 (PIQ) and comparable means (SDs) as follows: FSIQ, WPPSI-R, 100.6 (13.3) versus WPPSI-III, 99.4 (14.3); VIQ, WPPSI-R, 98.7 (13.9) versus WPPSI-III, 98.3 (13.2); and PIQ, WPPSI-R, 102.6 (13.3) versus WPPSI-III, 99.5 (14.9), in a subset of the normative sample tested with both versions.32 A score of below −3 SDs (<55) was defined as severe mental delay, below −2 SDs (<70) as intellectually impaired, and below −1 SD (<85) as concern for future learning ability.
Growth included length and weight, reported as percentiles,34 and head circumference, reported in SDs with microcephaly defined as >2 SDs below the mean for age.35 Parents completed the Multiattribute Health Status Classification (MAHSC),36 a comprehensive rating scale describing 8 attributes of health: sensation (vision, hearing, and speech), mobility, emotion, cognition, self-care, pain, behavior, and general health. Parents assigned functional ratings for each attribute with scores ≥2 being abnormal.
Assessment at Age 2 Years (22–23 Months)
Assessments were done at a mean (SD) of 22 (3) months, as described previously,22 gave the Mental Development Index (MDI) and Psychomotor Development Index (PDI) of the Bayley Scales of Infant Development, Second Edition.37 These scores are reported in this study for the 61 children assessed at age 5 years and are compared with the 5-year psychological scores.
To test the comparability of the 2 versions of the WPPSI in our population, we transformed FSIQ scores for each version into z scores.38 We then compared z scores, means (SDs), and percentages of delayed children of the groups of children tested with the 2 versions. Because there is an analogous normal distribution for both versions with a mean (SD) of 100 (15), the proportion of those delayed relative to normative values was considered combinable. To test this, a variable stating that the test version was included in the analysis and no association between the percentage of delay and version was found.
One-way analysis of variance with Scheffé multiple comparisons, t test, χ2 analyses, and Fisher's exact test (all 2-sided) were used to compare groups; Bonferroni correction was applied. Paired-samples correlations, and paired t tests looked for relationships between the 2-year and 5-year scores. Sensitivity, specificity, and positive and negative predictive values were calculated. Stepwise multiple regression was used to assess which combination of variables added to the prediction of the 5-year FSIQ; significance increment was a P value of <.05. SPSS 12.0 for Windows (SPSS, Inc, Chicago, IL) was used for analysis.
Of the 85 children with complex cardiac surgery at ≤6 weeks, 67 survived to 2 years, and their outcomes have been reported.22 Survival to age 5 years in relation to surgical group was as follows: arterial-switch operation, 23 (100%); simple total anomalous pulmonary venous connection, 6 (100%); hypoplastic left heart syndrome, 14 (54%); and miscellaneous surgical procedures, 23 (73%). The use of deep hypothermic circulatory arrest (n [%]) and cardiopulmonary bypass time (mean [SD]) for these groups were as follows: arterial-switch operation, 11 (55%) and 112 minutes (20 minutes); simple total anomalous pulmonary venous connection, 6 (100%) and 61 minutes (8 minutes); the Norwood procedure, 14 (100%) and 18 minutes (27 minutes); complete repair without chromosomal anomaly, 9 (69%) and 115 minutes (68 minutes); and complete repair with chromosomal anomaly, 5 (63%) and 100 minutes (42 minutes). Subsequently, 1 late death (post-Norwood, Glen, and Fontan) occurred (Fig 1). Of the 66 surviving children, 62 (94%) were followed to age 5 years. Data from 1 child with autism were omitted. Four were not assessed, but attending doctors confirmed that they were alive and free of impairment at 5 years of age. The 61 children assessed comprised 5 groups: 20 (33%) had undergone arterial-switch operation with (n = 14) or without (n = 6) intact ventricular septum, 14 (23%) had undergone the Norwood procedure, 6 (10%) had undergone simple total anomalous venous connection repair, and 13 (21%) had undergone other miscellaneous surgical procedures, with 8 additional children (13%) with miscellaneous procedures having confirmed chromosomal anomalies (deletion 22q11.2, Down syndrome). There were no differences in demographic variables among the 5 surgery groups. No child was born of a multiple birth, 42 (69%) were boys, 49 (80%) were white, 51 (84%) had 2-parent families, 55 (90%) had a birth weight of >2500 g, and 52 (85%) had English as their first language. One child required a qualified interpreter for testing. The mean (SD) socioeconomic status28 of the families was 43 (13) and mother's schooling was 13 (2) years.
Neuromotor or sensory impairment occurred in 3 (4.9%) of 61 children (Fig 1). One child with cerebral palsy had preoperative hypoxia and cerebral infarction. Another child with mild neurosensory hearing loss and visual impairment had hypoplasia of the optic nerves, an absent corpus callosum, and dysmorphic features, although molecular genetic investigation did not uncover a chromosomal anomaly. The third child had late-onset, high-frequency progressive sloping to profound sensorineural hearing loss thought to be associated with persistent pulmonary hypertension of the newborn.39
At 5 years, 45 children were tested using the WPPSI-R and 16 children were tested using the WPPSI-III. Comparisons between these 2 groups of children for FSIQ were as follows: z scores, WPPSI-R, −0.7 (1.4) versus WPPSI-III, −.6 (1.1), t = −.389, P = .7; mean (SD), WPPSI-R, 88.6 (19.9) versus WPPSI-III 91.4 (19.6), t = −0.654, P = .515; and proportion of children with delay (<70), 15% vs 6%, Fisher's exact test, P = .668. The use of deep hypothermic circulatory arrest for 45 (74%) of the 61 children did not alter the intelligence score: FSIQ after use, 89 (19) versus not used, 90 (22), t = 0.068, P = .946. Similarly, the duration of cardiopulmonary bypass time did not significantly correlate with FSIQ (r = 0.152). The following scores between children with English as a first language and other did not differ for mean (SD): FSIQ, English, 88 (20) versus non-English, 96 (15); and VIQ, English, 89 (20) versus non-English, 93 (10). However, PIQ was lower for children with English language, at 88 (21) versus non-English, 99 (11) (t = −2.356; P = .03). Using a stepwise multiple regression and the predictors of MDI, maternal education, socioeconomic status, surgical group, version of WPPSI used, and number of subsequent surgical procedures to predict FSIQ at 5 years, only MDI entered the equation. The adjusted R2 for MDI was 0.661 (β = .878; SE = .0181; t = 10.874; P = <.001).
Table 1 shows 2-year neurodevelopmental results and 5-year neurocognitive results for 61 children. Children with chromosomal anomalies had the lowest mean scores. Excluding these 8 children, no differences were noted among MDI, FSIQ, or VIQ scores. Again, excluding those with chromosomal anomalies, children after arterial-switch operation had higher scores than children after the Norwood procedure on PDI, PIQ, and VMI; similarly, those with total anomalous venous connection repair had higher scores than those after the Norwood procedure on PDI and VMI.
Paired-sample correlations tests between MDI and FSIQ scores as shown in Table 1 for all 61 of the children were high (MDI, 85 ; with FSIQ, 89 ; r = 0.817; P < .001). Similarly, for all 53 of the children without chromosomal abnormalities, correlations were also high (MDI, 88 ; with FSIQ, 94 ; r = 0.750; P < .001). The correlation between the MDI at 2 years and the FSIQ at 5 years after the Norwood procedure was very high (r = 0.9197; P < .001). For the 53 children without chromosomal abnormalities, paired t tests suggested higher scores at 5 years (88  to 94 ; t = −3.276; P = .002). For the subset of those after the arterial-switch operation, scores increased from the MDI at 2 years to the FSIQ at 5 years (94  to 101 ; t = −2.231; P = .038). Scores for other subgroups did not show a significant trend.
With all of the levels of mental delay, there were a high proportion of correct classifications of the 5-year scores as predicted by the 2-year scores (Table 2). Fewer children were delayed at 5 years than at 2 years. Scores for only 1 child with MDI results of <55 rose to >70 at 5 years; the remainder continued to have mental scores at <70 at 5 years. For the 53 children without chromosomal abnormalities, 14 (26.4%) had FSIQ scores <85. Of these 14, 7 had MDI scores <70, 5 others had MDI scores of 70 to 84, and for 2 children there was a decrease to below the average range. A drop in scores of these 2 children with average 2-year scores occurred in 1 child with a developmental language disorder after arterial-switch operation and in another with low PDI and PIQ scores resulting in a drop in FSIQ. Scores of a third child with below average scores and a developmental language disorder post–arterial-switch operation showed a drop of 19 points from an MDI of 81 to an FSIQ of 62.
Growth and health outcomes are outlined in Table 3. No child was using supplemental oxygen at age 5 years. Excluding children with chromosomal anomalies, 5 (9.4%) of 53 had length under the 5th percentile, 3 (5.7%) had weight less than the 5th percentile, and 3 (5.7%) had microcephaly. Surgical reintervention did not occur within all of the groups. Numbers are insufficient to determine whether subsequent surgery had an effect on outcome. This variable did not add to the prediction of FSIQ.
Parent report of health status (Table 4) differed significantly among surgery groups for all of the domains except pain and behavior. Children without and with chromosomal abnormalities differed in the proportion with abnormal scores on the domains as follows: sensation, 3 (6%) vs 4 (50%), P < .001; emotion, 6 (11%) vs 7 (88%), P < .001; cognition, 13 (25%) vs 7 (88%), P = .001; self-care, 11 (21%) vs 7 (88%), P = .001; pain, 10 (19%) vs 4 (50%), P = .07; behavior, 13 (25%) vs 6 (75%), P = .009; and general health, 5 (9%) vs 6 (75%), P < .001 (Fisher's exact test). No differences were found among those without chromosomal abnormalities.
This report adds to the literature about childhood outcomes after specific surgical procedures for neonatal and infant complex cardiac surgery by giving a direct comparison of neurocognitive results among survivors for several different procedures. This provides an advantage over editorial and summary articles,1,3,40 because procedures done in this study were completed during the same time period and from 1 institution, thus lending themselves to comparative analyses. Significant differences among groups have been reported previously,22 and these differences persist to age 5 years. The mean FSIQ results after arterial-switch operation for this cohort are within reference range and are similar to the average of scores found in published reports.4,6,8 Our results after repair of simple total anomalous pulmonary venous connection and palliative surgery for hypoplastic left heart syndrome are similar to those published.9,15 Lower neurocognitive results for those children with chromosomal anomalies reflect concerns published in recent reports.26,41
The strength of this study is the comparison of early childhood neurodevelopmental with preschool neurocognitive results. An upward trend of scores is noted from 2 to 5 years of age, excluding children with chromosomal anomalies. We used 3 levels relative to normative values to define concern for FSIQ scores. Cognitive scores of <55 reflect severe mental delay; scores rarely increase to average (≥85) or above if early delay is this severe. This finding is similar to reports in the literature showing that early childhood mental scores of <55 rarely increase to intellectual values within the normal range and, hence, are predictive of adverse mental outcomes.42 Cognitive scores of <70 define intellectual impairment as determined by the American Psychiatric Association and the American Association of Mental Retardation.43,44 Scores of ≥70 through 84 define children likely to have school learning difficulties. Prediction in this study for all of the children without chromosomal abnormalities with 5-year scores <85 from 2-year scores of <85 was correct in 12 (85.7%) of 14 children. This differs from a recent prediction of 8-year scores from 1-year MDI scores after surgery for transposition of the great arteries, where sensitivity was 16%, specificity was 83%, positive predictive value was 42%, and negative predictive value was 78%.23 Although there has been concern expressed about the limited predictive validity of mental test scores at toddler age,3,45 for future cognitive ability, this study shows strong correlation between 2- and 5-year testing and high negative predictive value within categories of intelligence. This information will enable better test interpretation and some reassurance when testing younger children. False-negatives were uncommon in our study, explained for 2 children by severe language disorders, resulting in lower scores on the largely language-based FSIQ. It is not clear whether the language disorders are linked to the underlying condition of transposition of the great arteries, the arterial-switch operation, or a coincidental finding.
We cannot comment on the predictive value of the PDI for motor scores at 5 years, because we did not formally assess preschool motor development. In our population, children after the Norwood procedure and complete repair with and without abnormal chromosomes have lower PDI scores at 2 years. We cannot compare our cohort with the recently reported results showing 49.4% of children delayed in fine motor and 39.0% delayed in gross motor skills.21
Enrollment of the children in early intervention or education before age 5 years was determined by the parents and their individual therapists or doctors. The groups with the lowest mean scores at age 2 years, that is, those with chromosomal anomalies, and those after the Norwood procedure, had the greatest proportion of children enrolled in early programs. Although early intervention for children at risk for developmental delay is recommended,46 it is not possible from this study to evaluate the role of early intervention or education in altering the 5-year scores. The numerous medical contacts for the cohort, evidenced by the number of hospitalizations and doctor's visits, provide opportunity for physicians to encourage enrollment in early intervention programs, thus supporting current recommendations.46
Many publications after complex cardiac surgery do not specifically report the inclusion or exclusion of chromosomal abnormalities among their populations.6–12,14–17 In this article, scores from children with confirmed chromosomal abnormality identify these children at greatest developmental risk, emphasizing the importance of clarifying genetic status when discussing outcomes.41 Preoperative parental counseling can be more complete if the chromosomal status is known.
We note a discrepancy between parents' perception of their child's health status on the MAHSC and documented health resource use. The results of the MAHSC are similar to those of other questionnaires on health status.11,14,15,24 We cannot find a publication that compared parents' perceptions of their child's use of health services with services used, but we suspect need for rehospitalization and chronic use of medications seem minimal to parents relative to the life-saving surgeries their child has had, hence their perception of relatively good health. Parental report of 30% of children having lower self-care than average reflects concern for self-care abilities, as reported previously.21 Children so reported by parents tend to be those for whom there is concern for cognition and behavior; thus, there is a group of children who are maturationally delayed. In this study, only 21% of the parents reported a concern for mobility, which is less than the 39% reported recently.21
Our cohort of children with neonatal and infant complex cardiac surgery compares favorably with other cohorts in the literature. Five-year survival was 100% for those after arterial-switch operation and repair of simple total anomalous pulmonary venous connection, 54% for those with hypoplastic left heart syndrome, and 73% for the remaining, comparable with published reports for this surgical era.1,4,6,9,46,47 As has been pointed out,20 we found that severe neuromotor or neurosensory sequelae after early complex cardiac surgery are uncommon. Microcephaly at 5 years was present in 3 (5.7%) of the 53 children without chromosomal anomalies in this study and is less than the 15.4% at a similar age reported recently.21 In this latter study, children with hypoplastic left heart syndrome and chromosomal anomalies were excluded, but some of the cohort were older at the time of initial surgery. It is possible that, by delaying surgery to later infancy, ongoing hypoxic insult or inadequate nutrition results in reduced brain growth at this vital time of synaptic development.
The major limitation of this study is the low number of patients. This was not a sample, because all of the children who met research entry criteria were registered, with 62 of 66 survivors assessed at 5 years and survival and impairment information obtained from attending doctors for the remaining 4 children. With larger numbers in each subgroup, the pattern of outcomes reported herein may change. Also, with larger numbers, we could comment on differences between those children after the Norwood procedure and others with single ventricle. A comparison between hypoplastic left heart syndrome and other functional single ventricle lesions is available.18 Another limitation is that not all of the children had full genetic investigation. Only those with conotruncal lesions or dysmorphism were routinely tested. New genetic consultations continued until age 5 years, particularly for delayed children; however, it is possible that a child with chromosomal abnormality and normal development may have been missed. We elected to omit children with autism, as did the Boston Circulatory Arrest Trial,4,5 and in accordance with current thinking.48 The frequency of autistic spectrum disorder is increasing; we chose to exercise caution and not attribute the diagnosis of autism in our child as a sequelae of care. If more children were diagnosed with autism in similar cohorts, one should consider including them as part of outcomes. A possible limitation is the use of combined results from the WPPSI-R and WPPSI-III. Data collection for this study extended over 3 years, during which time the intelligence test was revised. The option of continuing with the outdated test was rejected based on the principle of using the up-to-date version. With no difference between the means (SDs) of the 2 versions within the normative population and within our cohort and no effect delay attributable to a different version (using a dummy variable in the regression), we have proceeded to include all of the children in the cohort.
Significant neurodevelopmental differences in subgroups of toddlers after early complex cardiac surgery persist into the preschool years with fairly stable or improving trajectories of development. Loss of ability was found in 3 children, 2 with language disorders. Children with congenital anomalies and early complex cardiac surgery have significant challenges in all areas of development, health, and function. For children without chromosomal abnormalities, fewer children are intellectually impaired at 5 years than at 2 years. Specificity and high negative predictive values strongly suggest that children doing well at 2 years will continue to do well at 5 years.
Financial support was initially provided by Glenrose Rehabilitation Hospital Research Trust Fund with ongoing support from the Registry and Follow-up of Complex Pediatric Therapies Project, Alberta Health and Wellness.
The Western Canadian Complex Pediatric Therapies Follow-up Group includes P. Blakley (Saskatoon, Saskatchewan) and A. Ninan (Regina, Saskatchewan).
We thank the families of these children for their active participation in the developmental sites across western Canada and their commitment to this project. We sincerely thank the research coordinators who made this research study possible: H. Christianson and D. Anseeuw-Deeks (Calgary, Alberta); V. Debooy (Winnipeg, Manitoba); T. Martindale (Saskatoon, Saskatchewan); and L. Sanders (Edmonton, Alberta). We thank Dr A. Joffe (pediatric intensivist, Stollery Children's Hospital) for untiring collaboration in establishing this research.
- Accepted February 16, 2007.
- Address correspondence to Charlene M.T. Robertson, MD, FRCP(C), Room 242, GlenEast, Glenrose Rehabilitation Hospital, 10230-111 Ave, Edmonton, Alberta, Canada T5G 0B7. E-mail:
The authors have indicated they have no financial relationships relevant to this article to disclose.
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