The results of this single institution retrospective study suggest that the CDH-CPI may provide useful information for the counseling of parents with a fetus that has been diagnosed with an isolated left-sided CDH. There is a positive correlation between CDH-CPI score and survival. Patients with a score of 8 or higher have excellent outcomes with survival approaching 90%, whereas patients with scores lower than 8 had significantly decreased survival. A primary end point of this study was to determine if the CDH-CPI has a stronger correlation with survival than each of the individual component parameters. Our data suggest that of the 10 individual parameters, only TLV, LHR, and liver position significantly correlated with survival. In comparison, the CDH-CPI had a stronger degree of correlation than each of these individual parameters. This is probably because of the all-encompassing nature of this scoring index, which allows for more comprehensive prenatal counseling. It must be mentioned that it is counterintuitive that some other parameters did not significantly correlate with survival such as karyotype abnormality or CHD. This is probably because of the small number of patients who we had in each of these groups therefore no statistical significance. We additionally used logistic regression analysis to analyze the validity of our index to predict outcome in our data set. The CDH-CPI was able to accurately predict both survival and ECMO use.
Of all of the prenatal prognostic studies, LHR is the only validated prenatal predictor of CDH outcome [1
] but focuses purely on the lung hypoplasia component of the CDH with no significance given to the pulmonary hypertension, presence of genetic syndromes or the attributes of the hernia. Total lung volume [12
] and PPLV [4
] have shown promise in predicting survival but have only been examined in small case series and suffer from the same limitation as LHR of assessing only the lung hypoplasia component. The limitation of these measurements (LHR, TLV, PPLV) of lung hypoplasia is evident in the example of a fetus who may have a favorable LHR, but in light of a significant genetic syndrome or a significant cardiac defect, survival can potentially be greatly diminished. We have previously reported that significant heart defects can result in a 3-fold increase in mortality in patients with CDH [14
]. Liver herniation has also shown to be useful as it not only addresses the attributes of the hernia but also is a surrogate marker for lung hypoplasia. The main advantage of the CDH-CPI is that it takes into account several aspects of the fetus’ overall state of health and severity of the CDH, from the genetic and cardiac perspective and further includes both assessment of the pulmonary hypoplasia and the significant pulmonary hypertension that can be associated with CDHs. This may account for the stronger correlation with survival of the CDH-CPI as compared with the other individual parameters. We use this prognostic index in each of our prenatal CDH consults seen at the FCC of Cincinnati to counsel patients and provide expectant mothers on the likelihood of survival at our institution.
The CDH-CPI also positively correlated with ECMO use. Seventy-five percent of patients with a score of 5 or lower were placed on ECMO. This prenatal information is helpful in identifying high-risk fetuses who should be delivered at an institution offering advanced supportive measures such as ECMO. Furthermore, we use the lower CDH-CPI scores to identify high-risk babies who may be offered an alternative delivery strategy, such as EXIT to ECMO or have their cesarean delivery performed at the Children’s Hospital with the ECMO circuit primed and available in the same operative theater. This strategy in theory minimizes the potential risks to the baby during transport.
The limitations of this study include its retrospective nature allowing for possible observational bias. In addition, the data presented in this study are institutional specific, as postnatal CDH management is not standardized among major children’s institutions. Furthermore, albeit 64 patients included in the study is a clinically significant sample size, it is statistically small. This is especially true of the subset of patients who required ECMO use (19 patients), but our data would suggest that a CDH-CPI score of 5 or lower increased the likelihood for the need for ECMO (). These limitations can only be overcome by a much larger prospective study of the CDH-CPI in a multicenter collaboration.
In conclusion, the results of this study demonstrate that patients with a left-sided CDH and a CDH-CPI score of 8 or higher have a significantly higher rate of survival than patients with a CDH-CPI score lower than 8. These results may allow the surgeon to prenatally predict potential outcomes and appropriately counsel expectant mothers on severity and likely outcomes associated with CDH while potentially predicting the need for ECMO support. Such a tool may enable pediatric surgeons to objectively stratify patients and alter their delivery and postnatal management strategy.