Criteria abstracted from The Users' Guide to Medical Literature, from the Health Information Research Unit and Clinical Epidemiology and Biostatistics, McMaster University

Highlighted lines and questions below provide links to the pertinent description of criteria in The EBM User's Guide, now available at the Canadian Centres for Health Evidence

Article Reviewed:

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Predictors of developmental disabilities after open heart surgery in young children with congenital heart defects.

Limperopoulos C, Majnemer A, Shevell MI, et al.

J Pediatr. 2002;141(1):51-8. [abstract]

Reviewed by Lama Elbahlawan MD, LeBonheur Children's Medical Center. Memphis, TN

Review posted April 4, 2003

I. What is being studied?

Study objective:

The objective is to determine the prevalence of neurodevelopmental disabilities that persist in young children who have congenital heart disease (CHD). The secondary objective was to investigate factors that were associated with increased risk of developmental disability like perioperative clinical examinations, indicators of acute or persistent cardiorespiratory compromise, intraoperative procedures, and environmental factors.

Study design

Prospective observational study. This study examined the neurodevelopmental outcome of infants and children with CHD at Montreal Children's Hospital 12 months to 18 months after open heart surgery (OHS).

Patients included:

"Term infants with a diagnosis of a CHD undergoing their first corrective or palliative OHS before 2 years of age, with no clinical evidence of a disorder or impairment of the central nervous system due to causes other than complications of the heart defect at the time of admission for heart surgery."

Patients excluded:

Children with hypoplastic left heart syndrome and children with genetic syndromes or brain malformations discovered in the context of clinical care.

Outcomes evaluated:

• Neuromotor status: evaluated independently by a neurologist and by an occupational therapist (OT).
• Global development: evaluated by psychologist by using the Griffiths Mental Development Scale (GMDS).
• Cardiorespiratory status: examined by a cardiologist through review of the medical charts.
• Functional status: assessed by using the WeeFIM and the Vineland Adaptive Behavior Scale.
• Risk factors:
  1. The presence of microcephaly at surgery
  2. Preoperative and/or acute postoperative neurodevelopmental status.
  3. Duration of deep hypothermic circulatory arrest (DHCA) and cardiopulmonary bypass (CPB).
  4. The type of heart surgery ( corrective vs palliative).
  5. Cyanotic vs acyanotic CHD
  6. Socioeconomic status.
• Risk factors at the time of follow-up testing:
  • Growth parameters.
  • Number of subsequent hospitalizations.
  • Persisting cyanosis.
  • Ongoing

II. Are the results of the study valid?

Note: These questions follow from Randolph AG et al. Understanding articles describing clinical prediction tools. Crit Care Med 1998;26:1603-1612. [abstract]

1. Was a representative group of patients completely followed up? Was follow-up sufficiently long and complete? Was the sample representative of the larger population they were trying to sample from?

• 131 subjects recruited, 13 died and 20 did not undergo follow-up testing.
• No significant differences existed between patients who were followed up and those who were not followed up in baseline variables.
• Not all assessments were carried out on all subjects: all subjects were assessed by at least one evaluator, and 70% were assessed by 2 or 3 evaluators.
• In the 98 subjects evaluated, 45% had OHS as a neonate and 55% had OHS in infancy (first year of life) 87 had corrective surgery and 11 had palliative procedures.
• The distribution of the different congenital heart diseases and the types of surgery performed were described in a previous article by the same authors and appeared to be reasonable: tetralogy of Fallot (30), ventricular septal defect (13), transposition of the great arteries (10), double outlet right ventricle with subaortic ventricular septal defect (9), atrioventricular septal defect (8), including 1 with severe pulmonary stenosis, pulmonary atresia with intact ventricular septum (4), univentricular heart (4), interrupted aortic arch (3), double outlet right ventricle with subpulmonary ventricular septal defect (3), atrial septal defect (3), transposition of the great arteries with ventricular septal defect (3), coarctation of the aorta with aortic arch hypoplasia (3), including 1 with aortic arch hypoplasia, aortic valve stenosis (2), cortriatriatum (1), total anomalous pulmonary venous connection (1), and anomalous origin of the left coronary artery (1).

2. Were all potential predictors included?

• Cardiorespiratory status was assessed for each patient.
• Neurologic status was documented in 63/98 patients. It is therefore possible that the incidence of pre-existing neurologic abnormalities was underestimated.
• Motor performance and behavior was assessed in 81/98 patients.
• Developmental status was assessed in 61/98 patients.
• All risk factors that are believed to be pertinent were included in analysis.

3. Did the investigators test the independent contribution of each predictor variable?

• A univariate analysis was done to assess the association between each predictor variable and 1- Year outcomes. All predictor variables were included.
• Simple, multiple logistic regression, and multiple linear regression analysis were then performed as well.

4. Were outcome variables clearly and objectively defined?

• The outcome variables were clearly and objectively defined. The outcome variables included neurologic examination, Griffiths Mental developmental quotient, gross and fine motor impairment. The testing was performed by occupational therapists, psychologists and neurologists who were not aware of the original clinical history of the children. The cardiologist performing the chart review was blinded as to the outcome of the neurodevelopmental assessments.
• 90% of children had satisfactory cardiorespiratory status as determined by the cardiologist, 41% had an abnormal neurologic exam, and 33% had behavioral difficulties.

III. What are the results?

1. What is(are) the prediction tool(s)?

There is no prediction tool per se. Some of the significant important relationships from univariate analysis were (reported as outcome with predictors):

• Abnormal neurologic examination at follow up with preoperative neurodevelopment abnormality, preoperative microcephaly, postoperative neurodevelopment, postoperative microcephaly, DHCA duration, corrective vs palliative OHS, intensive care duration, length of hospitalization, weight, and persisting cyanosis.
• Microcephaly with preoperative neurodevelopment and microcephaly, postoperative neurodevelopment.
• Gross motor impairment with preoperative neurodevelopment, postoperative neurodevelopment, DHCA, intensive care duration, length of hospitalization, subsequent admissions, height and persisting cyanosis.
• Fine motor impairment with preoperative and postoperative neurodevelopment, preoperative and postoperative microcephaly, DHCA duration, cyanotic vs acyanotic CHD, length of hospitalization, weight, and height.
• Global developmental delay with preoperative neurodevelopment, preoperative microcephaly, postoperative microcephaly, DHCA duration cyanotic vs acyanotic CHD, intensive care duration, length of hospitalization.

2. How well does the model categorize patients into different levels of risk?

From the multiple regression analyses:

• Baseline examination (OR: 3.8, 95% CI 1.2, 12.2), length of DHCA (OR: 1.1, 95% CI 1.0, 1.2), and days in the intensive care units (OR: 1.1, 95% CI 1.1, 2.2) were predictive of neurologic abnormalities.
• DHCA (OR: 1.04 for each minute of difference, 95% CI 1.0, 1.08), length of stay in the intensive care unit (OR: 1.05, 95% 1.01, 1.12), preoperative neurodevelopmental status (OR: 4.7, 95% CI 1.1, 20.6), and acyanotic defects (OR: 9.3, 95% CI 1.5, 58.8) were predictive of fine motor impairments.
• Days in the intensive care unit, acyanotic defects, and increasing age at surgery were associated with gross motor delays (ORÕs not provided).
• Preoperative microcephaly (OR: 11.5, 95% CI 2.1, 64.9), abnormal preoperative and postoperative neurodevelopmental performance (OR: 10.5, 95% CI 1.2, 88.6), palliative vs corrective OHS (OR: 0.1, 95% CI 0.03, 0.47) were important markers for subsequent markers for subsequent global delays.

3. How confident are you you in the estimates of risk?

The 95% confidence intervals (noted above for the odds ratios in the multiple regression models) are quite broad for the most part, reducing our confidence somewhat. (The narrow CI's are typically for incremental risk factors, like each minute of DHCA or each day in the ICU)

IV. Will the results help me in caring for my patients?

1. Does the tool maintain its prediction power in a new sample of patients?

The model was not validated in a new independent sample of patients.

2. Are your patients similar to those patients used in deriving and validating the tool(s)?

Yes. The patients studied appear typical of a large congenital heart surgery program's population.

3. Does the tool improve your clinical decisions?

It identifies a high risk group for developmental disabilities following OHS. This study confirms that microcephaly and existing neurodevelopmental defects in the perioperative period are predictive of the neurologic outcome at followup. In addition, it is consistent with previous studies that showed the duration of DHCA is a predictor of neurologic problems. But given that different management strategies were not compared, it does not provide us with information to make different clinical decisions.

4. Are the results useful for reassuring or counseling patients?

This study is unique because it looked at predictors of developmental disabilities other than just the IQ. It helps in predicting patients who will have developmental and neurologic impairment following OHS in children with CHD. It is important to share with the parents the fact that there is a high incidence of behavioral and developmental disabilities following open heart surgery (~35%), although this should not stop surgical interventions since these are life saving.

It is important also to remember that 12-18 months is a relatively short follow up period, and that many infants and young children with developmental delays can make significant improvements throughout childhood.

References

1. Limperopoulos C, Majnemer A, Shevell MI, et al. Functional limitations in young children with congenital heart defects after cardiac surgery. Pediatrics. 2001 Dec;108(6):1325-31. [abstract]

 

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