Evolution of Pulmonary Hypertension and Associated Risk Factors In Children with Sickle Cell Disease

Published reports suggest that the prevalence of pulmonary hypertension (PHTN) in children with sickle cell disease (SCD) ranges from 20% to 30%; however, there is a significant variation regarding the age screening with echocardiography began in those studies. Similarly, various risk factors have been implicated but none has been consistently found associated with PHTN besides hemolysis. Furthermore, there is a paucity of the long-term data on the outcome of these children.

To determine the prevalence and progression of PHTN and its relationship with suspected risk factors in children with SCD receiving care at USA comprehensive pediatric sickle cell clinic.

Retrospective chart review of children, ages 5–19 years with SCD was performed. Children who had an echocardiogram in a steady state and had a regular check up during January 1^st 2006 and December 31^st 2007 were eligible for this study. Demographic and echocardiographic data and data regarding various other variables were collected. PHTN was defined as a tricuspid jet velocity (TRJV) of ≥ 2.5m/s on echocardiography which corresponds to a pulmonary artery pressure of 25mm Hg. Chi-square and t tests were used to analyze the categorical and continuous variables respectively. Prevalence odds ratio (POR) was obtained through a multivariate logistic regression model.

One hundred and eighteen children (53 males and 65 females) met the inclusion criteria. Five children were receiving chronic transfusion therapy during the study period. Thirty one children had a TRJV ≥ 2.5 m/s for an overall PHTN prevalence of 26% during the study period. Of these 31 children, 60% were older than 10 years of age and 55% were males. Children with and without PHTN were not different with respect to reticulocyte count, hemoglobin or fetal hemoglobin level, transcutaneous oxygen saturation, abnormal echocardiogram or pulmonary function results, history of chest syndrome or pain crises or stroke. Although the results did not reach statistical significance, the odds of being diagnosed with PHTN trended higher for males compared to females (POR 1.57; CI 0.65, 3.79), for children >10 compared to < 10 years (POR 2.41; CI 0.87, 6.63) and for those with HbSS compared to other genotypes (POR 1.73; CI 0.61, 4.92). No significant association was found between a diagnosis of PHTN and chronic transfusion therapy (POR 1.13; CI 0.32, 3.96). Follow-up of these children with routine echocardiogram over 3 years showed normalization in 14 while 11 children (nine were over 10 years of age) continued with a TRJV ≥ 2.5 m/s. Data were not available for 6 children.

Our study shows that the prevalence of PHTN in children with SCD during the study period was 26%. This is comparable to previously published reports. PHTN was most prevalent in children over 10 years of age. This suggests that screening with echocardiography may be cost-effective if started after 10 years of age. Our data further suggest that most of these children will normalize the TRJV overtime without any intervention. Further studies are needed in order to develop a cost-effective approach for identification of at risk children.

No relevant conflicts of interest to declare.