Pulmonary Hypertension in Pediatric Patients with Sickle Cell Disease; a Retrospective Study.

Background: While pulmonary hypertension (PHT) contributes significantly to the morbidity and mortality of adults with sickle cell disease (SCD), it has not been studied in pediatric SCD patients. We sought to evaluate the prevalence and significance of PHT in pediatric SCD population.

Methods: From May 1999 to July 2004, 123 echocardiograms were performed in SCD patients. Utilizing the tricuspid valve regurgitant jet, right ventricular systolic pressure (RVSP) was estimated in 56 studies (47 patients, aged 0 to 18 years). PHT was defined as RVSP >30 mmHg.

Mean steady-state as well as the most recent white blood count (WBC), hemoglobin (Hb) level, reticulocyte count, ferritin level, and number of red cell units transfused in the year prior to the study were noted. In addition, all chest X-ray readings were reviewed to determine the number and type of life-time pulmonary events (effusions, infiltrates, pneumonia, atelectasis or CHF) in each patient. Acute chest syndrome (ACS) was determined to be any effusion, infiltrate or pneumonia.

Statistical analysis included Fisher’s exact test and Spearman’s correlation coefficients.

Results: Eleven patients were acutely ill at the time of the echocardiogram and were excluded from the analysis. Of the remaining 36 patients, pulmonary hypertension was present in 24 (66%). There was a significant difference in RVSP between younger (0 to 9 years) and older (10 to 18 years) groups of patient (p<0.004). There was a positive correlation between the age and RVSP (r = 0.36; p = 0.031).

A significant negative correlation was shown between RVSP and most recent Hb (r = −0.41; p = 0.012) as well as RVSP and the mean steady state platelet count (r = −0.35; p = 0.035). A positive correlation was found between RVSP and the number of ACS episodes (r = 0.37; p = 0.024), RVSP and mean steady state reticulocyte count (r = 0.51; p = 0.002) as well as the most recent reticulocyte count (r = 0.42; p = 0.012). There was however, no correlation found between RVSP and the number of episodes of CHF, collapse or atelectasis separately or grouped together. No correlation was found between RVSP and the number of units transfused or ferritin level.

Conclusion: Pulmonary Hypertension is highly prevalent in the pediatric SCD population and its prevalence increases with age. It correlates with indicators of acute and chronic hemolysis as well as the number of ACS events. Our study did not demonstrate correlations between PHT and iron overload indices. Prospective clinical trials monitoring PHT in SCD pediatric patients are indicated.