Implications for current clinical practice and future research
The findings of this meta-analysis suggest that serum LDH differences are minimal among the various forms of hypertensive disorders of pregnancy. The only potential group that might benefit from the addition of serum LDH in standard preclinical evaluation is that of patients with severe preeclampsia. Maternal morbidity outcomes as well as perinatal mortality of the fetus/neonate were found increased among patients with an increased LDH value and particularly among those with LDH that exceeded 800 IU/L. However, the observed confidence intervals as well as prediction intervals indicated a wide range of the effect size; thus, indicating that the actual power of this biomarker was low in determining these adverse outcomes. Given this information we believe that it is difficult to determine the actual levels that may help discriminate patients at risk of experiencing adverse maternal or neonatal outcomes as current evidence is scarce and reports particularly heterogeneous optimal cut-off values.
Taking this into consideration, we believe that future research should focus in patients with severe preeclampsia and incorporate a predictive accuracy analysis that will help discriminate patients at risk of severe morbidity at specific cut-off points. Taking in mind that the increase of LDH might precede more severe adverse effects, such as acute hemolysis, kidney injury, pulmonary oedema, admission to the ICU and NICU it would be prudent to evaluate the optimal interval to delivery of patients with unaffected blood parameters (including platelets, creatinine, liver enzymes) that firstly develop an increase in serum LDH. In order to do so, future research should firstly establish an ideal cut-off value that is associated with increased specificity (and if possible, sensitivity) for developing severe morbidity. Following that, evaluation of the optimal interval to deliver will become possible.