Mariana Hildesheim

Nitric Oxide for Inhalation in the Acute Treatment of Sickle Cell Pain Crisis: A Randomized Controlled Trial

CONTEXT Inhaled nitric oxide has shown evidence of efficacy in mouse models of sickle cell disease (SCD), case series of patients with acute chest syndrome, and 2 small placebo-controlled trials for treatment of vaso-occlusive pain crisis (VOC). OBJECTIVE To determine whether inhaled nitric oxide gas reduces the duration of painful crisis in patients with SCD who present to the emergency department or hospital for care. DESIGN, SETTING, AND PARTICIPANTS Prospective, multicenter, double-blind, randomized, placebo-controlled clinical trial for up to 72 hours of inhaled nitric oxide gas vs inhaled nitrogen placebo in 150 participants presenting with VOC of SCD at 11 centers between October 5, 2004, and December 22, 2008. Intervention Inhaled nitric oxide gas vs inhaled nitrogen placebo. MAIN OUTCOME MEASURES The primary end point was the time to resolution of painful crisis, defined by (1) freedom from parenteral opioid use for 5 hours; (2) pain relief as assessed by visual analog pain scale scores of 6 cm or lower (on 0-10 scale); (3) ability to walk; and (4) patients and familys decision, with physician consensus, that the remaining pain could be managed at home. RESULTS There was no significant change in the primary end point between the nitric oxide and placebo groups, with a median time to resolution of crisis of 73.0 hours (95% confidence interval [CI], 46.0-91.0) and 65.5 hours (95% CI, 48.1-84.0), respectively (P = .87). There were no significant differences in secondary outcome measures, including length of hospitalization, visual analog pain scale scores, cumulative opioid usage, and rate of acute chest syndrome. Inhaled nitric oxide was well tolerated, with no increase in serious adverse events. Increases in venous methemoglobin concentration confirmed adherence and randomization but did not exceed 5% in any study participant. Significant increases in plasma nitrate occurred in the treatment group, but there were no observed increases in plasma or whole blood nitrite. CONCLUSION Among patients with SCD hospitalized with VOC, the use of inhaled nitric oxide compared with placebo did not improve time to crisis resolution. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00094887.

The relationship between the severity of hemolysis, clinical manifestations and risk of death in 415 patients with sickle cell anemia in the US and Europe

The intensity of hemolytic anemia has been proposed as an independent risk factor for the development of certain clinical complications of sickle cell disease, such as pulmonary hypertension, hypoxemia and cutaneous leg ulceration. A composite variable derived from several individual markers of hemolysis could facilitate studies of the underlying mechanisms of hemolysis. In this study, we assessed the association of hemolysis with outcomes in sickle cell anemia. A hemolytic component was calculated by principal component analysis from reticulocyte count, serum lactate dehydrogenase, aspartate aminotransferase and total bilirubin concentrations in 415 hemoglobin SS patients. Association of this component with direct markers of hemolysis and clinical outcomes was assessed. As primary validation, both plasma red blood cell microparticles and cell-free hemoglobin concentration were higher in the highest hemolytic component quartile compared to the lowest quartile (P≤0.0001 for both analyses). The hemolytic component was lower with hydroxyurea therapy, higher hemoglobin F, and alpha-thalassemia (P≤0.0005); it was higher with higher systemic pulse pressure, lower oxygen saturation, and greater values for tricuspid regurgitation velocity, left ventricular diastolic dimension and left ventricular mass (all P<0.0001). Two-year follow-up analysis showed that a high hemolytic component was associated with an increased risk of death (hazard ratio, HR 3.44; 95% confidence interval, CI: 1.2–9.5; P=0.02). The hemolytic component reflects direct markers of intravascular hemolysis in patients with sickle cell disease and allows for adjusted analysis of associations between hemolytic severity and clinical outcomes. These results confirm associations between hemolytic rate and pulse pressure, oxygen saturation, increases in Doppler-estimated pulmonary systolic pressures and mortality (Clinicaltrials.gov identifier: NCT00492531).

Exercise capacity and haemodynamics in patients with sickle cell disease with pulmonary hypertension treated with bosentan: results of the ASSET studies

Doppler‐defined pulmonary hypertension (PH) in sickle cell disease (SCD) is associated with 40% mortality at 40 months. To assess the effect of bosentan in SCD‐PH, two randomized, double‐blind, placebo‐controlled, 16‐week studies were initiated. Safety concerns are particularly relevant in SCD due to comorbid conditions. ASSET‐1 and ‐2 enrolled patients with pulmonary arterial hypertension (PAH) and pulmonary venous hypertension (PH), respectively. Haemodynamics and 6‐min walk distance (6MWD) were obtained at baseline and week 16. The studies were terminated due to slow site initiation and patient enrolment (n = 26). Bosentan appeared to be well tolerated. Although sample sizes were limited, in ASSET‐1 at baseline, 6MWD correlated with cardiac output (CO; P = 0·006) with non‐significant inverse correlations between 6MWD and pulmonary vascular resistance (PVR; P = 0·07) and between 6MWD and right atrial pressure (P = 0·08). In ASSET‐2 at baseline, there was a non‐significant correlation between 6MWD and CO (P = 0·06). Due to limited sample sizes, efficacy endpoints were not analysed. However, in both studies, non‐significant increases in CO were observed with bosentan compared to placebo. Similarly, non‐significant decreases in PVR were observed with bosentan. Limited data in SCD‐PH suggest that a low 6MWD predicts a low CO. Standard‐dose bosentan appears to be well tolerated. Further investigation is warranted. Clinicaltrials.gov registration numbers NCT00310830, NCT00313196, NCT00360087.

Plasma thrombospondin-1 is increased during acute sickle cell vaso-occlusive events and associated with acute chest syndrome, hydroxyurea therapy, and lower hemolytic rates

Platelets are activated in sickle cell disease (SCD), and particularly during vaso-occlusive episodes (VOE). Thrombospondin-1 (TSP1), a major secretory product of activated platelets, is increased in the circulation in VOE and binds to sickle red blood cells (RBC) promoting vascular adhesion. Thus, we hypothesized that TSP1 may represent a plasma biomarker of disease severity in SCD. We tested the plasma collected from patients in steady state (n = 27) and VOE (n = 14), as well as healthy controls (n = 17) at the University of Pittsburgh Medical Center (UPMC), and from patients in steady state enrolled in the walk-PHaSST clinical trial (n = 483). We found that TSP1 levels were increased in VOE in the UPMC cohort. Among steady-state patients at UPMC, TSP1 values correlated positively with lifetime history of acute chest syndrome (r = 0.72, P < 0.0001) and hemoglobin concentration (r = 0.49, P = 0.01), and negatively with markers of hemolysis, such as LDH (r = -0.50, P = 0.009). Analysis of the walk-PHaSST cohort also showed a positive association between TSP1 levels and hydroxyurea use (r = 0.14, P = 0.003), and confirmed the negative associations with the severity of hemolysis. Our results suggest that TSP1 levels are associated with more VOE, hydroxyurea use and lower rates of hemolysis. High TSP1 concentrations may indicate higher risk of the viscosity/vaso-occlusion phenotype of SCD.

Lipid levels in sickle-cell disease associated with haemolytic severity, vascular dysfunction and pulmonary hypertension

Pulmonary hypertension (PH) in sickle cell disease (SCD) is an emerging and important clinical problem. In a single‐institution adult cohort of 365 patients, we investigated lipid and lipoprotein levels and their relationship to markers of intravascular haemolysis, vascular dysfunction and PH. In agreement with prior studies, we confirm significantly decreased plasma levels of total cholesterol, high‐density lipoprotein‐cholesterol (HDL‐C) and low‐density lipoprotein‐cholesterol (LDL‐C) in SCD versus ethnically‐matched healthy controls. Several cholesterol parameters correlated significantly with markers of anaemia, but not endothelial activation or PH. More importantly, serum triglyceride levels were significantly elevated in SCD compared to controls. Elevated triglyceride levels correlated significantly with markers of haemolysis (lactate dehydrogenase and arginase; both P < 0·0005), endothelial activation (soluble E‐selectin, P < 0·0001; soluble P‐selectin, P = 0·02; soluble vascular cell adhesion molecule‐1, P = 0·01), inflammation (leucocyte count, P = 0·0004; erythrocyte sedimentation rate, P = 0·02) and PH (amino‐terminal brain natriuretic peptide, P = 0·002; prevalence of elevated tricuspid regurgitant velocity (TRV), P < 0·001). In a multivariate analysis, triglyceride levels correlated independently with elevated TRV (P = 0·002). Finally, forearm blood flow studies in adult patients with SCD demonstrated a significant association between increased triglyceride/HDL‐C ratio and endothelial dysfunction (P < 0·05). These results characterize elevated plasma triglyceride levels as a potential risk factor for PH in SCD.

NT-pro Brain Natriuretic Peptide Levels and the Risk of Death in the Cooperative Study of Sickle Cell Disease

Epidemiological studies support a hypothesis that pulmonary hypertension (PH) is a common complication of sickle cell disease (SCD) that is associated with a high risk of death and evolves as a complication of haemolytic anaemia. This fundamental hypothesis has been recently challenged and remains controversial. In order to further test this hypothesis in a large and independent cohort of SCD patients we obtained plasma samples from the Cooperative Study of Sickle Cell Disease (CSSCD) for analysis of a biomarker, N‐terminal‐pro brain natriuretic peptide (NT‐proBNP), which is elevated in the setting of pulmonary arterial and venous hypertension. A NT‐pro‐BNP value previously identified to predict PH in adults with SCD was used to determine the association between the risk of mortality in 758 CSSCD participants (428 children and 330 adults). An abnormally high NT‐proBNP level ≥160 ng/l was present in 27·6% of adult SCD patients. High levels were associated with markers of haemolytic anaemia, such as low haemoglobin level (P < 0·001), high lactate dehydrogenase (P < 0·001), and high total bilirubin levels (P < 0·007). A NT‐proBNP level ≥160 ng/l was an independent predictor of mortality (RR 6·24, 95% CI 2·9–13·3, P < 0·0001). These findings provide further support for an association between haemolytic anaemia and cardiovascular complications in this patient population.

Risk factors for death in 632 patients with sickle cell disease in the United States and United Kingdom.

Background The role of pulmonary hypertension as a cause of mortality in sickle cell disease (SCD) is controversial. Methods and Results We evaluated the relationship between an elevated estimated pulmonary artery systolic pressure and mortality in patients with SCD. We followed patients from the walk-PHaSST screening cohort for a median of 29 months. A tricuspid regurgitation velocity (TRV)≥3.0 m/s cuttof, which has a 67–75% positive predictive value for mean pulmonary artery pressure ≥25 mm Hg was used. Among 572 subjects, 11.2% had TRV≥3.0 m/sec. Among 582 with a measured NT-proBNP, 24.1% had values ≥160 pg/mL. Of 22 deaths during follow-up, 50% had a TRV≥3.0 m/sec. At 24 months the cumulative survival was 83% with TRV≥3.0 m/sec and 98% with TRV<3.0 m/sec (p<0.0001). The hazard ratios for death were 11.1 (95% CI 4.1–30.1; p<0.0001) for TRV≥3.0 m/sec, 4.6 (1.8–11.3; p = 0.001) for NT-proBNP≥160 pg/mL, and 14.9 (5.5–39.9; p<0.0001) for both TRV≥3.0 m/sec and NT-proBNP≥160 pg/mL. Age >47 years, male gender, chronic transfusions, WHO class III–IV, increased hemolytic markers, ferritin and creatinine were also associated with increased risk of death. Conclusions A TRV≥3.0 m/sec occurs in approximately 10% of individuals and has the highest risk for death of any measured variable. The study is registered in ClinicalTrials.gov with identifier NCT00492531

Severe painful vaso-occlusive crises and mortality in a contemporary adult sickle cell anemia cohort study.

Background Frequent painful vaso-occlusive crises (VOCs) were associated with mortality in the Cooperative Study of Sickle Cell Disease (CSSCD) over twenty years ago. Modern therapies for sickle cell anemia (SCA) like hydroxyurea are believed to have improved overall patient survival. The current study sought to determine the relevance of the association between more frequent VOCs and death and its relative impact upon overall mortality compared to other known risk factors in a contemporary adult SCA cohort. Methods Two hundred sixty four SCA adults were assigned into two groups based on patient reported outcomes for emergency department (ED) visits or hospitalizations for painful VOC treatment during the 12 months prior to evaluation. Results Higher baseline hematocrit (p = 0.0008), ferritin (p = 0.005), and HDL cholesterol (p = 0.01) were independently associated with 1 or more painful VOCs requiring an ED visit or hospitalization for acute pain. During a median follow-up of 5 years, mortality was higher in the ED visit/hospitalization group (relative risk [RR] 2.68, 95% CI 1.1-6.5, p = 0.03). Higher tricuspid regurgitatant jet velocity (TRV) (RR 2.41, 95% CI 1.5-3.9, p < 0.0001), elevated ferritin (RR 4.00, 95% CI 1.8-9.0, p = 0.001) and lower glomerular filtration rate (RR=2.73, 95% CI 1.6-4.6, p < 0.0001) were also independent risk factors for mortality. Conclusions Severe painful VOCs remain a marker for SCA disease severity and premature mortality in a modern cohort along with other known risk factors for death including high TRV, high ferritin and lower renal function. The number of patient reported pain crises requiring healthcare utilization is an easily obtained outcome that could help to identify high risk patients for disease modifying therapies. Trial Registration ClinicalTrials.gov NCT00011648 http://clinicaltrials.gov/

A pilot study of electronic directly observed therapy to improve hydroxyurea adherence in pediatric patients with sickle‐cell disease

Poor hydroxyurea (HU) adherence limits effective HU use in patients with sickle cell disease (SCD). Electronic directly observed therapy (DOT) may limit costs and achieve high HU adherence in children with SCD. This study aimed to determine if electronic DOT was feasible, acceptable, and could achieve ≥90% HU adherence.

Laboratory and echocardiography markers in sickle cell patients with leg ulcers

In this prospective cohort of adults with SCD, we confirm that leg ulcers are still frequent and are associated with elevated TRVand markers of hemolysis. We describe a novel association of leg ulcer with hyperuricemia and oxygen desaturation and suggest potential implications for uric acid as a marker of vascular dysfunction.